UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 BERKELEY, CALIFORNIA 
 
 OUT OF 
 
 CIRCULAR 276 nr%r - / ^. 
 
 March, 1924 
 Revised August, 1942 
 
 HOME CANNING 
 
 W. V. CRITESS 2 and A. W. CHRISTIE 8 
 Revised by W. V. CRUESS 
 
 CONTENTS 
 
 PAGE PAGE 
 
 Principles of canning 2 Special directions for vegetables 35 
 
 Equipment 5 Preservation of meats 40 
 
 General directions for canning 18 Condensed directions 41 
 
 Special directions for fruits 26 Vitamins in canned foods 41 
 
 Hot pack to save sugar and jars 33 Food poisoning 46 
 
 INTRODUCTION 
 
 Requests for information on the home canning of fruits and vegeta- 
 bles are received at this Station with increasing frequency. This circular 
 is intended to describe approved methods and also to give general infor- 
 mation asked for by numerous inquirers. 
 
 A large quantity of fruits and vegetables goes to waste every year or 
 is sold at prices which return little profit. Much of this, while unsuited 
 to the special requirements of the commercial cannery, is well adapted 
 to canning for home use. The quality may be as good as that of the prod- 
 ucts of commercial canneries if put up with the proper knowledge and 
 care. It is often possible to find a limited market for home products of 
 this kind at profitable prices. 
 
 Local and private markets are usually the most satisfactory for the 
 home or farm canner. He will seldom find it profitable to sell on the gen- 
 eral market through dealers in competition with commercial canneries. 
 
 1 The writers desire to express their appreciation to Professor F. T. Bioletti, Dr. 
 K. F. Meyer, Dr. J. C. Geiger, Dr. S. H. Ayers, Dr. J. R. Esty, Dr. C. A. Magoon, Mr. 
 A. Richardson, and others for valuable suggestions given during the preparation and 
 revision of the original manuscript for this circular; and Miss Hilda Faust for addi- 
 tions to and revisions of the present edition. 
 
 2 Professor of Fruit Technology and Chemist in the Experiment Station. 
 
 3 Assistant Professor of Fruit Products and Associate Chemist in the Experiment 
 Station: resigned June 30, 1928. 
 
 [1] 
 
University of California — Experiment Station 
 
 PKINCIPLES OF CANNING 
 
 CAUSES OF SPOILING 
 
 The principal aim of canning is to prevent spoiling. Spoiling is not dne 
 directly to the action of air or of heat and it is not simply a chemical or 
 a physical change. When vegetable materials ferment, decay, or turn 
 sour, the spoilage is due to the growth of certain microscopic living 
 organisms, or germs. These all belong to the vegetable kingdom and are 
 divided into three groups : molds, yeasts, and bacteria. Familiar exam- 
 ples of each group are the blue-green mold of spoiled fruits, the yeast 
 used in bread making, and the bacteria of the scum, or mother, of vine- 
 gar. What we see in compressed yeast, for instance, is simply a mass 
 consisting of millions of germs. Individual germs are too minute to be 
 seen without a microscope. Their activities cause the molding of jellies, 
 the swelling and souring of canned fruits, the spoiling of canned vege- 
 tables, and the putrefying of meats. The character of the material 
 largely determines which type of spoiling will occur. Acidity is favor- 
 able to yeasts and molds. Fruits may therefore spoil by yeast fermenta- 
 tion or become moldy. Most bacteria prefer a medium with little or no 
 acid. Decay of vegetables or meats is therefore usually due to the action 
 of bacteria. Neither fruits nor acid vegetables are favorable to the growth 
 of most bacteria. 
 
 Yeasts, molds, and bacteria are widely distributed and occur in the 
 air, in water, on fruits and vegetables, and in great abundance in soil 
 and dust. Hence at the time of canning not only the fruit or vegetable 
 but also the sirup or brine and the containers are more or less heavily 
 contaminated with all manner of microorganisms. 
 
 METHODS OF PRESERVING 
 
 The microorganisms which cause spoiling come from the air or from 
 the surfaces with which the material comes in contact. They can no more 
 develop from nonliving matter than wheat can appear spontaneously in 
 soil devoid of wheat seed. In food preservation, we are dealing with liv- 
 ing organisms, whose activities can be prevented in one of two ways : we 
 may kill all the germs present by heat or other means and prevent the 
 entrance of all others, or we may make the conditions so unfavorable to 
 the germs that they cannot grow or do any damage. The latter way is 
 followed when we impregnate meat with so much salt that bacteria can- 
 not grow, or add so much sugar to jam that yeast cannot multiply. The 
 heat method is utilized in most methods of canning. 
 
Gib. 276] HOME CANNING 3 
 
 Sterilization by Heat. — The killing of all germs present is called 
 sterilization. In canning, this is accomplished by heating. The material 
 to be preserved is placed in a jar or can, in which it is sealed hermetic- 
 ally, that is, the container is made airtight. It is then heated to a tem- 
 perature fatal to all the germs it contains. No spoiling can then take 
 place until the vessel is opened, since there are no means by which germs 
 can enter. 
 
 Molds and yeasts that occur on fruits and vegetables are quickly killed 
 at temperatures below 212° Fahrenheit, the boiling point of water at 
 sea level. On the other hand, bacteria that cause spoiling of vegetables 
 are much harder to kill, many of them withstanding the temperature of 
 boiling water for several hours. These bacteria owe their astonishing 
 resistance to the presence of spores. 
 
 These bacteria with resistant spores probably occur on fruits, but it is 
 usually not necessary to kill them in this case, for they are very sensitive 
 to acidity and therefore usually cannot grow in fruit juices. Fruits low 
 in acid, such as figs and overripe pears, apricots, and peaches, are an 
 exception to this statement. Bacteria will grow in canned fruits when 
 the acidity is low. With vegetables the case is different. These, with the 
 exception of tomatoes and rhubarb, have little acidity and are well 
 suited to the growth of the heat-resistant bacteria. To sterilize vegeta- 
 bles it is therefore usual to heat the sealed cans to temperatures above 
 212° F. The temperature can be raised to boiling, which is approximately 
 212° at sea level, by placing the sealed cans in an open tank or pot con- 
 taining boiling water. But under these conditions no higher tempera- 
 tures can be reached, because the evolving steam removes the excess of 
 heat as fast as it is applied. At high elevations water boils at tempera- 
 tures below 212.° In a closed space where the steam cannot escape, how- 
 ever, higher temperatures can be obtained. As the temperature rises the 
 pressure increases. In canning vegetables, pressures of 5 to 15 pounds 
 to the square inch are generally used. This corresponds to temperatures 
 of approximately 227° to 249° ; the higher the pressure the higher the 
 temperature. 
 
 Acidified Brine. — Experiments in the Fruit Products Laboratory of 
 the College of Agriculture and in other laboratories have demonstrated 
 that nonacid vegetables can be safely sterilized at 212° F in acidified 
 brines. This method is used at present commercially for artichokes. How- 
 ever, owing to the difficulty of measuring accurately the brine and the 
 acidifying ingredient (vinegar, fruit acid, or lemon juice) in the home, 
 the method is not recommended at present for home use.* 
 
 4 First described in : Cruess, W. V. Home and farm canning. California Agr. Exp. 
 Sta. Cir. 158 : 1-31. 1916. (Out of print.) 
 
4 University of California — Experiment Station 
 
 Sterilizing Nonacid Vegetables. — In home canning, as explained later 
 in this circular, nonacid vegetables are preserved by several different 
 methods of sterilization. However, as far as the western states are con- 
 cerned only one of these methods, sterilization in steam under pressure, 
 that is, in a pressure cooker, is recommended. For the nonacid vege- 
 tables, such as asparagus, peas, corn, string beans, spinach, and the root 
 vegetables, the various methods of sterilizing at the boiling point of 
 water or in an oven are unsafe, and should not be used in the region 
 specified. 
 
 Drying and Pickling Nonacid Vegetables. — In the home it is often 
 more convenient and safer to preserve vegetables by pickling in brine or 
 by drying than by home canning. Drying is recommended in preference 
 to canning of certain nonacid vegetables, particularly string beans, 
 peas, corn, and spinach. Directions for these other methods will be sent 
 on application to the Agricultural Extension Service, College of Agri- 
 culture, Berkeley. 
 
 Sterilizing Fruit Juices. — Heating fruit juices to 212° F always 
 changes the flavor more or less. In a few cases, this change of flavor may 
 be an improvement, but in most cases it is desirable to retain as much 
 of the original character of the juice as possible. This is accomplished 
 by careful handling and by heating to the lowest temperature that will 
 insure sterilization. Experiments have shown that most juices can be 
 safely sterilized at temperatures of from 175° to 185°. (See Extension 
 Circular 65. 5 ) 
 
 Preservatives. — Food materials can be prevented from spoiling by 
 the use of certain substances known as preservatives. Some of these are 
 injurious to health and forbidden by the pure-food laws. Others are not 
 encouraged by the pure-food laws, because they have been used by un- 
 scrupulous manufacturers to disguise defective materials or careless 
 methods of manufacture. The use in canning of such preservatives as" 
 benzoate of soda, salicylic acid, sodium fluoride, boric acid, etc., is not 
 recommended. 
 
 Certain preservatives, however, are useful and permissible. For fruits, 
 sugar is the preservative most commonly used. If the sugar content of 
 fruit juice, jelly, or jam is raised to 70 per cent by evaporating part of 
 the water, or by adding sugar, these products become unsuitable for the 
 growth of microorganisms and will keep even in open vessels. This is 
 why dried fruit does not spoil and why jam must be made very sweet. 
 
 For some products salt is extensively used, as in preserving olives in 
 barrels and in keeping certain types of pickles. Vinegar and spices are 
 
 5 Cruess, W. V. Preparation of fruit juices in the home. California Agr. Ext. Cir. 
 65:1-15. 1933. 
 
ClR - 276 ] Home Canning 5 
 
 used in the same way. Sometimes a combination of the effects of heat 
 sterilization and harmless preservatives such as vinegar is used in the 
 preserving- of pickles, etc. 
 
 HOT- AND COLD-PACK METHODS 
 
 The principles and theory of canning are the same whatever the scale 
 on which it is done. The differences are only in the mechanical details 
 of the methods. 
 
 There are two general methods of home canning in use. In one, known 
 as the "hot-pack method/' the material is cooked in open pots and poured 
 into the cans while hot, together with the hot brine or sirup. The cans 
 are sealed immediately, and should be sterilized by further heating. In 
 the other, the "cold-pack method," the freshly prepared material is 
 placed cold in the cans and then covered with the hot sirup or brine, 
 sealed, and sterilized. "With both methods the material is always hot 
 when the cans or glass jars are sealed. The cold-pack method is generally 
 the best for vegetables, while the hot-pack method can often be used to 
 advantage with fruits, if supplemented by sterilization in the container. 
 This last method is advised for use in the present war-time emergency 
 as it requires fewer jars or cans; the product is packed without added 
 liquid. 
 
 EQUIPMENT 
 GENERAL EQUIPMENT 
 
 Most of the utensils and materials needed in home canning are to be 
 found in all kitchens. They include a good stove ; a table for the prepara- 
 tion of materials ; a sink ; a good supply of water ; various agateware or 
 aluminum pots, saucepans, and buckets ; large cooking spoons ; and a 
 sufficient supply of sugar and salt. To these should be added a good 
 thermometer, reading to at least 250° F and suitable for placing in 
 liquids (cost, about $1.50). A Balling or Brix saccharometer, or sugar 
 tester, is also very useful where fruit is to be canned on a farm scale. It 
 should read from to 70 per cent and costs about 75 cents. For use with 
 this will be needed a tin cylinder to hold the liquids to be tested. It should 
 be about 1% inches in diameter and about 12 inches long (fig. 11). The 
 thermometer and saccharometer can often be obtained through a drug- 
 store or local dealer. 
 
 Simple tools generally useful are shown in figure 1. These are a knife 
 (A) fitted with a guard to prevent excessive waste of pulp in peeling, 
 and a broad knife (B) for cutting and slicing. For clingstone peaches a 
 special spoon (C) with sharp edges is used. A curved knife (D) is used 
 
6 University of California — Experiment Station 
 
 for removing the cores of halved pears. A coring knife (E) is used for 
 coring apples. A cherry pitter (fig. 13) is very useful. Slicing and cub- 
 ing machines are available for vegetables. 
 
 Fig. 1. — Knives used in canning: A, peeling knife; 
 B, cutting knife; C, peach-pitting spoon; D, pear-coring 
 knife; E, apple-coring knife. 
 
 STERILIZERS 
 
 A sterilizer is a vessel in which the filled cans or jars are heated to the 
 degree and for the time necessary to sterilize their contents. 
 
 Sterilizers for Use at Boiling Point. — An ordinary wash boiler fitting 
 the top of the kitchen stove can be made to serve as a very satisfactory 
 sterilizer for use at the boiling point of water. A piece of heavy wire 
 screen of half -inch mesh or a wooden rack cut to fit should be placed in 
 
ClR - 276] Home Canning 7 
 
 the bottom of the boiler to prevent breaking of the jars. Inexpensive and 
 very satisfactory jar racks are now obtainable at most hardware stores. 
 Such a rack is shown in figure 15. 
 
 Use of Baking Oven. — Many home canners and some equipment deal- 
 ers have the mistaken belief that jars of food heated in a baking oven 
 attain the temperature of the oven. This is a very serious and dangerous 
 error. They reach only the temperature of boiling water, at sea level 
 namely 212° F, because as soon as the boiling point is reached the con- 
 tents of the jars boil, steam escapes from beneath the lid, and conse- 
 quently the temperature cannot exceed that of boiling water. Home 
 canners are warned against this dangerous fallacy. See the next para- 
 graph. 
 
 Pressure Sterilizers. — A steam pressure sterilizer is necessary for 
 most vegetables. This form of sterilizer permits the obtaining of tem- 
 peratures above the boiling point of water because the steam is confined 
 and heated under pressure. The sterilizer consists of a metal cylinder 
 and a heavy cap that fits the cylinder. The cap is easily removed or 
 fastened in place by releasing or tightening thumb screws (fig. 2) . 
 
 The pressure cooker is fitted with a thermometer or a pressure gauge, 
 
 a release cock, and safety valve. The thermometer is much more reliable 
 
 than the pressure gauge. In buying a pressure cooker, specify that it be 
 
 equipped with a dependable thermometer. Pressure gauges often get out 
 
 of order and become unreliable. Directions for its use accompany the 
 
 sterilizer. 
 
 JARS 
 
 Glass jars are excellent for home canning of fruits because they can 
 be used repeatedly. Their relatively high initial cost is offset by this 
 advantage. 
 
 Glass jars are to be found in a variety of sizes and shapes and with 
 various methods of hermetic sealing. The sizes most used are pints and 
 quarts and to a smaller extent half-gallons. The only important varia- 
 tion in shape is the width of the mouth which may be as wide as the jar 
 or only about half its width. The commonest method of sealing is by 
 means of a rubber ring which fits between the cover and the top of the 
 jar (fig. 3). 
 
 In the Mason jar and its various modifications the cover is a screw cap 
 which makes a hermetic (airtight) joint when screwed down on the rub- 
 ber ring. In the ordinary form this cap is of zinc with a porcelain lining. 
 This is the commonest form. Aluminum and heavily lacquered metal 
 caps are to be preferred to zinc caps because of the tendency of the zinc 
 to corrode with sour fruits and tomatoes. Wide-mouthed Mason jars are 
 

 Fig. 2. — Pressure sterilizer for home use, with safety valve at 
 left, thermometer in center, and release cock at right. 
 
 now made which are very convenient for large fruits. However, the large 
 enameled metal screw caps (fig. 3, D) are often difficult to remove and 
 may be broken in opening the jar. 
 
 In another common form, of which the Atlas "E-Z" seal jar is an 
 
ClR - 276] Home Canning 9 
 
 example, the cover is a glass disk held in place and pressed down on the 
 rubber by means of a strong wire clamp. After the fruit cools the clamp 
 may be removed and the cover will be held in place by the vacuum. This 
 affords a means of detecting spoiled jars. If there is any fermentation of 
 the fruit, the gas formed will fill the vacuum and the cap will be loosened. 
 This is a very convenient and durable form of cover, and no metal parts 
 are in contact with the fruit. 
 
 Special vacuum-sealed glass jars are used in jelly and preserve fac- 
 tories. They have enameled metal caps resting on heavy, soft rubber or 
 rubber-compound rings that are held in place by a vacuum inside the 
 
 
 -J 
 
 A B C D E F 
 
 Fig. 3. — Types of jars used in home canning: A, glass-top jar; B, Mason jar 
 with lacquered metal top; C, Economy jar; D, Golden State wide-mouth Mason 
 jar ; E, vacuum seal, glass-top jar; F, Mason jar with zinc top. 
 
 jars. For home use some forms of these jars may be sealed by forcing the 
 caps on by hand, while the contents are hot. On cooling, a vacuum is 
 produced which holds the caps firmly in place. 
 
 Recently a very satisfactory new form of glass top, automatically seal- 
 ing vacuum-seal jar for home use has appeared. It requires no special 
 equipment. It is made in several sizes of jars and should prove particu- 
 larly useful for home canning of fruits, preserves, and jellies. 
 
 In all cases where poor rubbers are used in sealing they must be spe- 
 cially treated, for they will otherwise give a disagreeable taste to the 
 food. Fruit and vegetables are sometimes completely spoiled by this 
 taste. It can be avoided by thoroughly boiling the rubbers in water made 
 alkaline with two or three teaspoons of washing soda to the quart. They 
 are then rinsed and boiled a second time in water made slightly acid 
 with lemon juice or vinegar. A third short boiling in plain water fits 
 them for use. There are now several good brands of jar rubbers which do 
 not require this treatment. They can be placed directly on the jars from 
 the package and should be used if obtainable. Owing to the war emer- 
 
10 University of California — Experiment Station 
 
 gency, rubbers may soon be unobtainable. Therefore save used rubbers 
 for re-use later. 
 
 In some forms of jars, the rubber ring is replaced by a disk of treated 
 or varnished pasteboard. This is not commonly used and is less generally 
 suitable because it usually does not give an airtight seal. 
 
 A commoner type that avoids the use of rubbers is the Economy jar 
 and its modifications. The cover is a lacquered metal disk around the 
 edge of which runs a small groove filled with a waxlike compound. When 
 the jar and its contents are cooling the vacuum formed seals the lid to 
 the jar. A metal spring holds the cover in place on the Economy jar and 
 is removed after cooling. This is jar C in figure 3. Lids should be new 
 and fresh. Used lids cannot be employed a second time, because of the 
 difficulty of securing an airtight seal. On the Kerr "self-sealing" jar the 
 lid is held in place by a screw band, which should be screwed firmly in 
 place before putting jars in the sterilizer. 
 
 Glass jars are suitable for use in a pressure sterilizer, although fre- 
 quently much of the liquid (brine or sirup) boils out of the container, 
 causing the jar after sterilization to be only three quarters or one half 
 filled with liquid, unless considerable care is used during sterilizing and 
 cooling. As more fully described in the section on use of the pressure 
 sterilizer (page 23), if the jars and contents are heated to the boiling 
 point and sealed tightly before the pressure sterilizer is closed, little to 
 no liquid is lost from the jars. The cooker should be cooled slowly after 
 the sterilization has been completed ; this will greatly lessen the tendency 
 for liquid to boil out of the jars during cooling. 
 
 These difficulties are overcome in commercial canneries by the use of 
 compressed air in the pressure cookers, but this is not feasible in the 
 home. In sterilizing jars under pressure the cooker should be operated 
 as directed in the section, "Sterilizing Under Pressure." 
 
 CANS 
 
 There are three general types of cans used for fruit and vegetables — 
 the wax-top, the solder-top, and the Sanitary. 8 While it is realized that 
 cans may not be obtainable during the war, this section is retained for 
 use when cans are again available. 
 
 The cover of the wax-top can is sealed on by means of a ring of hot 
 sealing wax. It is suitable for use with fruits and tomatoes, but it is not 
 satisfactory for vegetables which require high temperatures. The cans 
 are easily manipulated and require no special equipment. 
 
 Solder-top or stud-hole cans with the necessary soldering tools are 
 
 8 "Sanitary" is a trade name and when applied to this type of can does not imply 
 that other cans are unsanitary. 
 
Cir. 276] 
 
 Home Canning 
 
 11 
 
 used in some factory-made home-canning outfits and can be used with 
 any outfit if proper sealing tools are available. The top of the can has a 
 circular opening varying in width with the size and type of cans. After 
 filling the can, this opening is closed by soldering on a tin disk. This disk 
 is usually perforated with a small hole to allow steam to escape during 
 the preliminary heating. This hole must be closed with solder before the 
 final sterilization (fig. 4, G) . This style of can, except for very few prod- 
 ucts, is now seldom used commercially and is difficult to obtain. For 
 these reasons it is not recommended for home use. 
 
 '% (1 
 
 !*C 
 
 i w '] 
 
 " 
 
 Fig. 4. — Types of cans used in home canning: A, no. 1 tall Sanitary can; B, 
 no. 2 Sanitary can; C, no. 2% Sanitary can; D, no. 3 Sanitary can; E, no. 10 
 Sanitary can ; F, quarter-sized wax-top can ; G, no. 2 solder-top can. 
 
 Sanitary cans are not sealed with solder. The cover or cap is "crimped" 
 on by means of a special machine. A rubber coating or paper gasket on 
 the cap where it comes in contact with the can makes the sealing doubly 
 sure. Very satisfactory hand-power machines for home use can be ob- 
 tained at moderate cost (fig. 5) . 
 
 Sanitary cans are very satisfactory containers for vegetables to be 
 sterilized under pressure in the home. Where the quantity of vegetables 
 is too small to warrant purchase of a can sealer, it is possible for several 
 families to join in the purchase and use of such a machine. The cost is 
 approximately $20. 
 
 Cans may be obtained which are coated inside with a protective 
 enamel. These are suitable for red fruits, berries, and beets because they 
 minimize bleaching of the red color through action of the tin. 
 
 Sealing Sanitary Cans. — Sanitary cans are more satisfactory for home 
 use than solder-top cans. 
 
 In using Sanitary cans in home canning the prepared food is packed 
 
12 
 
 University of California — Experiment Station 
 
 into the washed can and boiling hot sirup or brine is added to fill it. In 
 commercial canning the can and contents are heated in live steam or hot 
 water for 4 to 10 minutes before sealing in order to expel air from the 
 food and liquid. While such preliminary heating is desirable it is not 
 
 ^ 
 
 Fig. 5. — Small hand-power sealing machine for Sanitary cans. 
 
 essential in home canning, provided the can is filled with o oiling hot sirup 
 or brine and sealed at once. 
 
 The general appearance and method of using a hand-power Sanitary 
 can sealer are shown in figure 5. To use the sealer proceed as follows : 
 
 1. Clamp the sealer to a stout table top. Place the lid on the can and set 
 the can on the turntable. Kaise the turntable by swinging the elevating 
 lever from the operator until it will go no farther. 
 
Cir. 276] 
 
 Home Canning 
 
 13 
 
 2. Turn the crank rapidly and at the same time push the seaming roll 
 lever very slowly away from the operator to bring the roll number one 
 against the top of the can until it will go no farther. Fifteen turns of the 
 crank should be sufficient. 
 
 / 
 
 r,rj» Operation Roll 
 
 & 
 
 first Operation Roll 
 
 Second Operation RoU 
 
 Fig. 6. — Sealing a Sanitary can. (After Cruess and Chris- 
 tie.) 1, Lid in place before sealing; 2, Appearance of lid and 
 edge of can after first operation ; 3, Appearance after second 
 operation. 
 
 3. Continue turning the crank rapidly and pull the seaming roll lever 
 slowly toward the operator until it will go no farther. Give the crank 
 several more turns and remove the sealed can. Do not turn too long or 
 the seam will be broken. 
 
 Figure 6 illustrates the top of the can before sealing, after the first 
 seaming operation, and after the final operation. Sealing a Sanitary can 
 is spoken of as "double seaming." 
 
 Automatic Sealers. — An improved home-sized can sealer which forms 
 the seams automatically has appeared on the market. 
 
14 University of California — Experiment Station 
 
 Comments on Seaming. 7 — The double seam, that is, the can closure, 
 consists of five thicknesses of tin plate, interlocked, or folded and pressed 
 firmly together. 
 
 When the rolls on the can sealer are correctly adjusted the hook of the 
 can lid is curled under the hook of the can by the first seaming operation. 
 The second seaming operation forces the several thicknesses of plate 
 tightly together and draws the gasket of the lid tightly against the top 
 of the can. The action of the rolls in double seaming (forming the can 
 seal) is shown in figure 6. Figure 7 shows schematically correct and in- 
 correct methods of forming the double seam. Incorrect seaming may be 
 due to too heavy or too light pressure on the seaming rolls ; or to incorrect 
 setting of the rolls. 
 
 Correct pressure in using hand-power sealers is a matter of practice 
 obtained under the supervision of an experienced person. In order to 
 determine whether your double seaming (forming the can seal) is satis- 
 factory, compare it with that on the other end of the can, that is, the 
 manufacturer's double seam. 
 
 The can-sealer rollers are correctly adjusted by the manufacturer ; it 
 is well to observe the setting of the rolls on the new machine as pur- 
 chased. With use the rollers and their shafts wear so that the rollers no 
 longer come sufficiently close to the chuck (the circular revolving disk 
 on top of the sealer). The seam is then apt to be too loose or otherwise 
 defective and slight adjustment becomes necessary. The first-operation 
 roller should clear the chuck by about the thickness of a new dime; the 
 second-operation roller should come very slightly closer than this to the 
 chuck. If a commercial cannery is nearby, it may be possible to have the 
 cannery's mechanic adjust the rollers for you occasionally. 
 
 With prolonged use the rollers become so badly worn that they must 
 be replaced. In such a case new rollers may be secured at moderate cost 
 from the manufacturer or dealer. 
 
 The rollers must be kept well oiled ; any good grade of machine oil or 
 medium-heavy cylinder oil will do. 
 
 Fruit juices and brine are very corrosive on the moving parts of the 
 sealer ; therefore, when sealing is completed for the day, wash the ma- 
 chine with hot water and dry it in the sun or above the stove, so that it 
 will not rust or corrode. 
 
 Choice of Lid. — Can lids are sealed to the can either with a rubber 
 composition which lies in the outer groove of the lid, or with a rather 
 spongy paper gasket (paper washer) lying in the lid's outer groove. 
 The use of paper gaskets has, however, been practically discontinued. 
 
 7 Much of the information presented on testing can seams has been taken from a 
 booklet, "The Double Seam," issued by the American Can Co., Maywood, Illinois, to 
 whom thanks are due. 
 
Cir, 276] 
 
 Home Canning 
 
 15 
 
 The rubber composition gasket requires very careful and accurate 
 setting of the rollers and considerable skill and experience in operating 
 the sealer. 
 
 Testing the Seam. — Unless the seaming is correctly done the can will 
 leak; air with yeasts and bacteria will enter, and the canned product 
 will soon spoil. The condition of the double seam (can seal) can be judged 
 by filing a notch through the seam of an empty sealed can and separat- 
 ing the lid hook from the double seam as shown in figure 8. Directions 
 for filing are given below the figure. 
 
 Fig. 7. — Correct and incorrect methods of forming the double 
 seam (can closure). A, Correct first operation for paper gasket — a, 
 top of can, b, body of can ; B, correct first operation for compound 
 (rubber) gasket; C, correct second operation for paper gasket; D, 
 correct second operation for compound gasket; E, incorrect first 
 operation for paper gasket, bottom seam too much flattened, and 
 cover hook curled under too tightly from too much pressure ; F, simi- 
 larly for compound gasket; G and H, first operation too loose, too 
 little pressure. (Courtesy of the American Can Co.) 
 
 Next clean all gasket material from beneath the can hook. Then insert 
 the narrow end of the can-testing ruler into the can hook as shown in 
 figure 9. A small pocket lens is useful in reading the ruler. If a can ruler 
 is not available, cut a narrow strip of tin plate and scratch a mark on 
 it Yxq inch from the end; use it as directed above for ruler. 
 
 The countersink is the distance between the top of the seam and top 
 of the can as shown at the left in figure 10 ; it should measure % inch. 
 The depth of can hook and of countersink are the only two measure- 
 ments made. Slight variation is permissible in these specifications ; but 
 appreciable variation indicates incorrect seaming. 
 
 The double seam as exposed in the notch filed as shown in figure 8 will 
 tell much concerning the correctness of seaming. The folds must not 
 
Fig. 8. — Filing a can's double seam to determine whether seaming has been 
 done correctly or not. A, File a notch through at the body seam to the body of 
 the can ; B, starting at notch file barely through the first thickness of plate for 
 a distance of about 1 to 2 inches; C, use file to force down the cover hook, the 
 narrow thickness of plate as shown; D, bend the cover hook up, as shown, for 
 observation and measuring of the can hook. (Courtesy of the American Can Co.) 
 
 Fig. 9. — Flat file used in filing cans and thin metal ruler used in measuring 
 can body hook, can lid hook, and width of seams. The notches in ruler are for 
 measuring width of the double seam. 
 
 COUNTERSINK 
 
 Scale: 
 
 Fig. 10. — Left, diagram of double seam showing can hook, cover 
 hook, and countersink. Right, showing method of testing depth of 
 can hook ; this should be % 6 inch. (Courtesy of the American Can Co.) 
 
Cir. 276] Home Canning 17 
 
 appear pinched, for that indicates excessive pressure, which may cause 
 cracking of the plate and leaking of the seam. If the pressure has been 
 too low the seam will appear too open. It is again suggested for emphasis 
 that the can maker's end of the can also be filed and examined for com- 
 parison with the seam made by yourself. It is also good practice to make 
 occasional comparisons with seams on cans of commercially packed 
 foods. By such means your double-seaming operations can be judged. 
 
 In case of doubt, however, several of your cans, after sealing, should 
 be sent or taken to the nearest manufacturer of cans or to your County 
 Home Demonstration Agent for inspection of the double seams and ad- 
 vice for correction of any defects in sealing. During the present emer- 
 gency it is likely that it will be difficult to purchase cans for home use. 
 
 Locating the Leaks in Seams. — Frequently leaks in the double seam 
 can be located by dropping the can after sealing, sterilizing, and cooling 
 into a pot of hot water. Bubbles of gas forced out of the can by the heat 
 will appear at the leaky point. However, this test is not infallible be- 
 cause occasionally the leak is plugged temporarily with a particle of 
 food. "Pumping the can" is another means of detecting faulty sealing. 
 As far as small-scale canning is concerned the following procedure may 
 be employed. Seal an empty can. Punch a small hole in the center of the 
 top. To the top of the can and over the hole solder a bicycle tire or auto- 
 mobile tire valve. Attach a bicycle pump and then completely immerse 
 the can in a pot or bucket of cold water. Pump can to about 20 to 25 
 pounds of pressure as indicated by a tire gauge. If seams are faulty, bub- 
 bles of air usually appear at the leaking point. Or you may take the cans 
 to a garage and have a mechanic make the above test for you. However, 
 the hot-water test described above is usually adequate. 
 
 Re flanging and Using Cans a Second Time. — Some home-sized can 
 sealers are equipped with a can-opening roller and a reflanger. The 
 manufacturer of the sealers have recommended that many cans may be 
 reflanged and used a second time. However, experience has not been 
 entirely satisfactory with this procedure owing to the difficulty of secur- 
 ing a perfectly airtight seal at point of union of side seam of can and 
 the double seam on top of the can. Also many cans are considerably cor- 
 roded by the can contents during the usual several months' storage in 
 the pantry, and hence are unsuitable for use a second time. 
 
 On the other hand, an experienced and skillful operator may use some 
 of the cans a second time if particular care is taken in opening the can, 
 reflanging, and in adjusting the can-sealer base to the proper height. 
 The booklet accompanying the sealer gives specific directions and illus- 
 trations for carrying out these operations. 
 
18 University of California — Experiment Station 
 
 GENERAL DIRECTIONS FOR CANNING 
 
 PREPARATION OF FRUITS 
 
 Nearly all fruits and vegetables require some kind of preparatory 
 treatment before canning. This may be washing, sizing, sorting for color 
 or ripeness, peeling, pitting, coring, or slicing. In some cases special 
 machines or tools are necessary. 
 
 The Raw Materials. — With the exception of pears, fruits for canning 
 are best if tree-ripened and canned as promptly after picking as possi- 
 ble. Fruit purchased in the markets of large cities is usually picked im- 
 mature. It is therefore of poorer flavor than that which is tree-ripened, 
 often lacks sugar, and may be more or less wilted or overripe. City 
 housewives will rarely find such fruit either economical in price or equal 
 to freshly picked ripe fruit in quality. 
 
 Sorting and Grading. — Moldy and soured fruit should be discarded 
 — it is not only unfit for food but is more liable to develop botulinus 
 poison if improperly sterilized. 
 
 Overripe, but sound fruit, should be used for jam rather than for 
 canning. 
 
 If the canned product is to be sold, it should be carefully graded for 
 size, color, and maturity into two or three grades. These may be desig- 
 nated first quality (finest and most nearly perfect specimens), standard 
 quality (sound fruit of fair quality), and pie fruit (small, slightly 
 blemished, or overripe fruit). 
 
 Washing. — Clean fruit is essential to success. Wash all fruit thor- 
 oughly before canning. 
 
 Hand-peeling. — If only small lots of fruit are to be canned, hand- 
 peeling is the most practical method. A guarded knife, like that shown 
 in figure 1, A, is desirable for soft fruits such as peaches and pears, 
 while the knife shown in figure 1, E, is perhaps more satisfactory for 
 peeling and coring apples. 
 
 Mechanical Peeling. — If a relatively large quantity of apples is to be 
 canned, some form of mechanical peeler is desirable. Hardware stores 
 can supply an inexpensive hand-power peeler for kitchen use. A more 
 expensive type peels and cores, or peels, cores, and slices the apple in 
 one operation. This is very useful for preparing apples for drying. 
 
 Mechanical peelers for other fruits are not very satisfactory. 
 
 Lye-peeling. — To lye-peel peaches or apricots, first prepare in an 
 agateware or iron kettle (never aluminum) a lye solution of % pound 
 (4 ounces or about 6 level tablespoons) of ordinary granulated lye, in 2 
 
Cm. 276] Home Canning 19 
 
 gallons of water. Heat to boiling, and while actively boiling immerse the 
 peaches (halved clingstones or whole freestones) or whole apricots in 
 a wire basket in the boiling solution until the skin is loosened and par- 
 tially dissolved. This will usually require 30 to 60 seconds. Remove and 
 wash in water until skin and lye are removed. Rinse thoroughly in fresh 
 water. Washing away the skin and lye under a jet of water from a faucet 
 is much more effective and satisfactory than washing in still water. If 
 the peels do not slip off easily, add a little more lye to the solution ; if 
 the lye cuts too deeply, immerse the fruit a shorter time. To avoid dark- 
 ening, store the peeled fruit in dilute cold brine, about 2 rounded table- 
 spoons of salt per gallon of water. Lye added to a hot solution spatters 
 and may cause serious bums; use care in adding it. If the solution at- 
 tacks the hands, rinse them in vinegar ; this will neutralize the lye. 
 
 It will not be found worth while to attempt to lye-peel small lots of 
 fruit, but the method will save a great deal of time if 50 pounds of fruit 
 or more are to be peeled. Lye-peeled fruit should be canned at once or 
 stored in cold dilute brine to avoid undue darkening. 
 
 Coring and Pitting. — Pears are peeled and cut in half, and the core 
 is then removed by the knife shown in figure 1, D, or by means of a sharp 
 teaspoon. 
 
 Dessert cherries are usually canned without pitting, but sour or sweet 
 cherries intended for use in pies should be pitted before canning. A 
 mechanical pitter, such as that shown in figure 13, is more convenient 
 than the small pitters operated by the thumb and two fingers. 
 
 Clingstone peaches are difficult to pit unless the spoon shown in figure 
 1, C is used. To use this spoon, first cut the peach to the pit completely 
 around the suture (crease). Insert the pitting spoon (also known as pit- 
 ting knife) from the stem end of the peach until the point of the spoon 
 rests at the blossom end of the pit. Rotate the spoon until one half of the 
 peach separates. Then scoop the pit from the other half. Pitting is best 
 done before peeling. 
 
 Freestone peaches and apricots need only be cut in half and the pit 
 removed with the point of the cutting knife. 
 
 PREPARATION OF VEGETABLES 
 
 Most vegetables require thorough washing. This removes not only soil 
 but also many of the microorganisms that cause spoilage. In addition to 
 peeling, shelling, slicing, or other preliminary preparation, most vege- 
 tables are blanched, that is, parboiled in boiling water or steam. 
 
 Vegetables as purchased in city markets are usually too costly for 
 home canning ; commercially canned vegetables are much cheaper. Vege- 
 
20 University of California — Experiment Station 
 
 tables from the markets are also apt to be wilted and tough and are 
 usually much more difficult to sterilize than vegetables direct from the 
 garden. Only freshly gathered vegetables should be used for canning. 
 
 Tomatoes are readily peeled after immersion in boiling water for 
 about 1 minute and chilling in cold water. The cores should be removed 
 at the same time, but if possible without opening the seed sacs. 
 
 Beets require about 10 to 15 minutes' boiling or steaming to loosen 
 the skin ; sweet potatoes require a longer time. Other root vegetables are 
 peeled by hand. 
 
 Mechanical peelers for vegetables are too costly for home use. 
 
 PACKING FRUIT 
 
 Most fruits may be packed into jars or cans after preparation and 
 without previous blanching or cooking. They should be arranged to pre- 
 sent a neat appearance in the jars. 
 
 Some fruits, unless cooked for a short time before packing, soften 
 during sterilizing and give partially filled containers. Berries for this 
 reason should be cooked with an equal weight of sugar before packing. 
 This is best done by adding the dry sugar to the fruit in a preserving 
 kettle, bringing to a boil, and boiling gently 3 to 4 minutes. The juice 
 of the fruit forms a sirup with the sugar — usually an excess of sirup 
 unless the mixture be allowed to stand overnight to permit absorption 
 of the sirup by the fruit. It may then be packed and sterilized in the jars 
 or cans. 
 
 Apples should be cooked in boiling water and apricots in boiling di- 
 lute sirup 3 to 4 minutes to soften them and cause shrinkage. They may 
 then be packed hot. If this is not done, the jars will be only partially full 
 after sterilization. 
 
 All fruits, in order to conserve can and jar space, may be cooked a 
 short time with sugar and a small amount of water as shown in figure 14. 
 Some home canners prefer this to the cold-pack method. The objection 
 to it is that some fruits become broken and present a less attractive 
 appearance than cold-packed fruit. 
 
 Cold-packing of the raw fruit is recommended for peaches, pears, 
 plums, prunes, and cherries. 
 
 BLANCHING 
 
 Certain vegetables should be blanched or parboiled before canning. 
 This is done by dipping them in boiling water or heating in steam. A 
 wire screen basket or a frying basket, such as is used in cooking dough- 
 nuts, will serve to hold the vegetables while they are dipped in a large 
 
Cir. 276] Home Canning 21 
 
 cooking pot containing boiling water. This treatment improves the qual- 
 ity, by removing slimy substances and lessening the astringent taste of 
 the skins. It is advisable with asparagus to remove bitterness. Blanching 
 also softens the vegetables so that a larger amount may be packed into 
 the jar or can. Blanching of peas, string beans, and greens such as spin- 
 ach is better done in steam than in water because there is then less loss 
 of water-soluble vitamins and valuable food materials. 
 
 When the vegetables are blanched in water, use this water, lightly 
 salted, for filling the jars; this procedure retains much of the water- 
 soluble vitamins and other food values removed by the blanch water. 
 
 Apples and apricots should also be blanched as described above in 
 order than a full can may be obtained. 
 
 EXHAUSTING 
 
 This process is desirable with nearly all airtight containers which 
 are to be sterilized by heat. It consists of a preliminary heating before 
 sealing and before the final sterilization. It results in expanding the air 
 inside the container and thus drives out most of the air. When the sealed 
 container and its contents cool, the small amount of air still enclosed 
 contracts and produces a partial vacuum. If cans are sealed while the 
 contents are cool they will swell on heating, owing to the expansion of 
 the heated air. In order to avoid breakage, jars should not be tightly 
 sealed before sterilization at the boiling point. However, recently 8 it has 
 been found that jars of vegetables to be heated in a pressure sterilizer 
 should be heated to the boiling point and sealed tightly before closing 
 the sterilizer in order that the liquid will not boil out of the jars during 
 heating and cooling. Exhausting is not necessary because the lid permits 
 escape of air and expansion of contents. The manufacturer recommends 
 that lids of Kerr "self -sealing" jars be screwed on firmly before placing 
 in sterilizer. If cans are packed with hot products, boiling hot sirup or 
 brine added, and the can sealed at once, exhausting can be omitted. If 
 merely warm or cold brine or sirup is added, the can should be heated 
 in live steam or boiling water for at least 5 minutes before sealing. 
 
 SIRUPS 
 
 Fruits are canned in sugar sirups of various strengths or concentra- 
 tions. The sugar so used has no preservative effect ; it is used only for 
 sweetening. Heating is what preserves the fruit. In general, the more 
 acid fruits require the most sugar. The appropriate strengths are given 
 in the directions for canning the various fruits. 
 
 8 This new procedure has been found satisfactory by Miss Hilda Faust and others 
 of the Home Demonstration Office. 
 
22 
 
 University of California — Experiment Station 
 
 At the time this edition goes to press sugar is scarce and subject to 
 rationing. In another section, directions are given for canning without 
 sugar or by methods requiring a minimum of sugar. 
 
 Brix or Balling Sugar Testers. — Sirups of the desired strengths may 
 be made up by weighing the sugar and measuring the water, or by add- 
 ing sugar to the water until the desired strength is indicated by the sugar 
 tester or hydrometer. This is sometimes called a saccharometer and the 
 
 commonest forms are the Brix and the Ball- 
 ing. The hydrometer is floated in a sample 
 of the sirup contained in a tall, narrow 
 metal or glass cylinder and the sugar per- 
 centage read from the scale at the surface 
 of the liquid. If the sirup is cold the read- 
 ing is correct enough for the purpose, but 
 if very hot the reading may be several per 
 cent too high (fig. 11). If large quantities 
 of fruits are to be canned for sale the use of 
 a hydrometer is recommended ; but for the 
 usual home canning of fruits it is not 
 needed. 
 
 Baume Sugar Tester. — This is a hy- 
 drometer similar in form to the Brix, dif- 
 fering only in the scale, which reads in 
 degrees instead of per cent. The degrees 
 may be multiplied by two to give the per 
 cent approximately. 
 
 Strength of Sirups. — For all practical 
 purposes sirups for home canning may be 
 prepared without a hydrometer with the 
 following proportions of sugar and water : 
 light sirup, 1 cup of sugar to 4 cups of 
 water ; medium, 1 cup sugar to 2 of water ; 
 and heavy, 1% cups of sugar to 1 of water. 
 The amounts of sugar to be added to 1 gallon of water to make sirups 
 of the concentrations used in home canning are as follows : 
 Light sirup, 20 degrees Balling, 2 pounds 2 ounces 
 Medium sirup, 40 degrees Balling, 5 pounds 10 ounces 
 Heavy sirup, 60 degrees Balling, 12 pounds 10 ounces 
 
 In making the sirups the desired weight of sugar is added to 1 gallon 
 of water and dissolved by warming and stirring. The volume of sirup 
 obtained is greater than that of the water used. For 1 quart of water use 
 
 Fig. 11. — Cylinder, thermom- 
 eter, and Balling sugar tester. 
 The tester in the cylinder of 
 sirup is read at the surface of 
 the liquid. In the illustration 
 this is approximately 12 per 
 cent. 
 
Gib. 276] Home Canning 23 
 
 one-fourth the amounts of sugar noted above. Water may be used in 
 place of sirup, for sugar is not necessary in home canning of fruits. 
 
 Cane and Beet Sugar. — In numerous tests made by the Fruit Prod- 
 ucts Laboratory, beet sugar was found to give results equal to those of 
 cane sugar. The prejudice against beet sugar is no longer warranted. It 
 is identical chemically with cane sugar. Beet sugar is equally as good as 
 cane sugar for jellies and preserves and is used by many canners and 
 preservers. 
 
 Adding the Sirup. — The sirup should be boiled, strained to remove 
 solid impurities, and poured into the jar or can boiling hot (see fig. 12) . 
 
 BRINES 
 
 For most canned vegetables a brine of about 2 per cent salt is used. 
 
 This corresponds to about 2% ounces or about 5 level tablespoons of 
 
 salt per gallon of water. Unless otherwise directed, this brine, boiling 
 
 hot, should be used to fill all cans of vegetables, except tomatoes and 
 
 rhubarb. 
 
 STERILIZING AT THE BOILING POINT 
 
 For sterilizing at the boiling point the sterilizer containing the cans 
 and several inches of water is placed on a stove, and steam generated 
 by boiling the water heats the cans. See figures 14 and 15 for method of 
 using this sterilizer. 
 
 Cans may be placed in two or more tiers, separated and supported by 
 slat gratings which allow the steam to penetrate to all parts of every 
 can. The cover of the boiler should fit snugly in order that the steam will 
 be confined and heat the upper part of the sterilizer to the boiling tem- 
 perature. A cloth should be placed between the cover and the top of the 
 boiler if the cover does not fit tightly (see fig. 15) . The times of steriliza- 
 tion given for the various products are to be calculated from the time the 
 water first boils. For the reasons given on page 7 the oven method of heat- 
 ing packed jars or cans of food is very unsafe and should not be used. 
 
 STERILIZING UNDER PRESSURE 
 
 In using the pressure sterilizer about 3 inches of hot water is added. 
 The water is previously heated to boiling. The sealed cans are then placed 
 in the crate and lowered into the sterilizer. Glass jars are filled with the 
 scalding hot vegetables and boiling hot brine and loosely sealed as di- 
 rected for sterilizing at 212° F. The water is gently boiled with the re- 
 lease cock open for about 10 to 15 minutes for vegetables in brine and 
 15 to 20 minutes for corn, spinach, or other tightly packed products. 
 Then the cooker is opened and the jars tightly sealed. This procedure 
 
24 University of California — Experiment Station 
 
 will prevent loss of liquid during sterilizing and will prevent breaking 
 of jars. Instead of heating the jars to the boiling point in the pressure 
 cooker they may be heated in a separate pot for the time indicated and 
 then sealed boiling hot. 
 
 Heat is then applied until steam escapes freely from the open cock. 
 This cock is then closed and heating continued until the temperature 
 reaches the desired point. (See table 2.) At this point the safety valve 
 should be set for the corresponding pressure. At the same time the re- 
 lease cock is opened slightly, so as to allow a small escape of excess steam. 
 By this means the temperature can be regulated very closely. After 
 reaching the temperature the cooker should be placed over a small flame 
 so that escape of steam will not be too rapid. The safety valve will open 
 and relieve the pressure if the temperature begins to go too high. For 
 cans, when the heating has continued for the required time, the cooker 
 is removed from the fire, the release cock opened full, and when the 
 pressure has fallen to the cans are removed and cooled in water. If 
 the cooker is opened before the pressure has fallen to 0, steam may scald 
 the operator. For glass jars open the valve very slightly so that only a 
 very small jet of steam escapes. Opening the valve too wide will cause 
 much of the liquid to boil out of the jars. As soon as the pressure has 
 fallen to the cooker should be opened. Remove the jars and tighten 
 seals at once on those jars on which the tops have loosened during steri- 
 lizing. 
 
 The larger outfits of this kind are equipped with a small steam boiler 
 for heating, and three or more cookers. Pressure sterilizers are usually 
 operated at 5, 10, or 15 pounds' pressure, corresponding to 227°, 239°, 
 and 249° F respectively. 
 
 Pressure gauges often become highly inaccurate and unreliable 
 through use. Every home pressure sterilizer to be used for the home 
 canning of vegetables should be equipped with a thermometer. Ther- 
 mometers retain their accuracy well and are not affected by different 
 altitude. 
 
 CAUTION! If the jars are not full when removed do not open them 
 and add brine to fill. Such added brine is not sterile and may cause fatal 
 poisoning later. Seal the jars at once whether they are full or not. 
 
 CLOSING AND COOLING JARS AND CANS 
 
 After the sterilizing period is completed in the 212° F sterilizer or 
 after the pressure in the pressure cooker has fallen to (with the re- 
 lease valve opened very slightly), remove the jars without in any way 
 disturbing the seal on jars from the pressure cooker ; screw or clamp the 
 
da- 276] Home Canning 25 
 
 tops tightly on jars sterilized in steam or in boiling water at 212° and 
 invert the jars to cool in a room free from cold drafts. The exceptions to 
 this rule are Economy and Kerr "self-sealing" jars, which are not in- 
 verted. Tops of Economy jars must be clamped tightly. CAUTION 7 
 Jars from a pressure cooker are apt to be under great pressure when the 
 cooker is opened. Allow them to cool 10 to 15 minutes before handling 
 them, otherwise one or more may burst and injure the operator. 
 
 Cans are sealed before sterilization, and are removed and chilled to 
 about blood temperature in cold water after sterilization. 
 
 MARKING CANS AND JARS 
 
 All containers should be plainly marked with the variety and grade 
 of the product. Cans may be marked by means of a small set of rubber 
 stamps and canner's ink, which will stand hot water, or by means of a 
 lead pencil. They may also be marked by means of a splinter of wood 
 dipped in strong copper sulfate solution. Gummed labels do not stick 
 well to tin. Jars may also be marked after sterilization with gummed 
 labels or wax pencils specially made for writing on tin and glass. 
 
 All lots should be dated. Such labeling and records will be found 
 valuable in locating cause of spoilage, should this occur. 
 
 STORAGE AND SPOILAGE 
 
 Before any canned fruit is put on the market, it should be stored at 
 least a month to see if it will show spoilage. It is better to have cans 
 spoil in the storeroom than on the grocers' shelves. If the fire used to 
 heat the sterilizer is not hot enough, it may take too long to bring the 
 cans to the temperature of boiling water and the organisms that cause 
 spoilage may not be killed. Often, however, the trouble is due to leaks 
 in the cans. With an inexperienced operator, leaks often occur around 
 the seam of Sanitary cans or in the solder groove of the cap of solder- 
 top cans. When the sealing operation is well done, there should be very 
 few leaks. Leaks can be detected by bubbles appearing when the cans 
 are placed into hot water. Leaks permit air to enter and the air brings 
 with it the organisms which cause the fruit or other product to ferment 
 or spoil and produce the gas that causes the cans to swell. Jars should be 
 stored in a dark, cool place. 
 
 Spoiled cans or jars of food should never be tasted or used. They may 
 contain Bacillus botulinus, and be deadly poisonous. Do not feed spoiled 
 canned food to fowls or animals — it may poison them. Many cases of 
 poisoning of chickens by spoiled home-canned foods are on record. See 
 also discussion of food poisoning in a later section. 
 
26 University of California — Experiment Station 
 
 SPECIAL DIRECTIONS FOR FRUITS 
 
 In figures 14 and 15 is illustrated a method of saving sugar and jars. 
 
 The fruit is cooked soft with very little water and no sugar ; or is cooked 
 
 with a small amount of sugar and then is canned hot and sterilized as 
 
 illustrated. Precooking and no addition of liquid saves greatly on jars 
 
 and sugar. 
 
 APPLES 
 
 Canned apples are used principally for pies. Any variety will do for 
 this purpose, but canners in California are limited largely to Bellflower, 
 Yellow Newtown, and Gravenstein, since these are the chief varieties 
 grown in the state and available culls are chiefly of these varieties. 
 
 To prepare, peel, core, quarter, and blanch in boiling water or steam 
 for 3 to 4 minutes. Pack hot, then fill the jar with boiling water, and 
 process as directed in table 1. 
 
 Applesauce may be prepared in the ordinary way. Pack scalding hot 
 into jars or cans. Sterilize as for canned apples. 
 
 PEABS 
 
 The Bartlett is the best variety for canning purposes. Fruit for can- 
 ning is harvested while still green but after it has reached full size. It is 
 allowed to ripen in boxes. The fruit is peeled by hand and cored with the 
 coring knife shown in figure 1, D, or with a sharp spoon. 
 
 Since pears tend to turn brown rapidly after peeling, they should be 
 placed in the can with sirup as soon as peeled, or should be kept under 
 water or dilute brine (2 tablespoons of salt per gallon of water) after 
 peeling until used. Pack into jars or cans and add hot medium or light 
 sirup, or water. See table 1 for sterilization or prepare and can as di- 
 rected in figures 14 and 15. 
 
 PEACHES 
 
 There are many varieties of peaches available for canning. Of the 
 clingstone varieties, the Tuscan, various midsummer varieties, and 
 Phillips Cling are very satisfactory ; and of the freestones, the Lovell, 
 J. H. Hale, Crawford, and Elberta are preferred. 
 
 Peel and pit as directed in the section "Preparation of Fruits." Pack 
 in cans or jars and add hot medium or heavy sirup. See table 1 for fur- 
 ther directions. 
 
 Peaches may be canned in plain sirup or in a sweet spiced vinegar 
 made as follows : 
 
 Sugar 3 pounds Ginger root ^4 ounce 
 
 Vinegar 1 pint Whole cloves % ounce 
 
 Water 3 pints Stick cinnamon % ounce 
 
Cm. 276] 
 
 Home Canning 
 
 27 
 
 Bring this mixture to boiling. Let stand overnight to absorb spice 
 flavor. Strain to remove spices, reheat to boiling, add hot to the fruit 
 in the jar or can, and sterilize according to table 1. 
 
 If sugar and jars are scarce the fruit may be prepared and canned as 
 directed in the hot-pack method shown in figures 14 and 15. 
 
 APRICOTS 
 
 Apricots for canning should be ripe and well colored, but not too soft. 
 If overripe, the fruit cooks down to a jam of unattractive appearance. 
 Blanching for 3 to 4 minutes in boil- 
 ing sirup before packing is desira- 
 ble, so that the container will be full 
 after sterilizing. 
 
 Apricots require a heavy sirup to 
 bring out their best flavor. See table 
 1 for further directions. To save 
 sugar and jars, prepare and can as 
 shown in figures 14 and 15. 
 
 \\\ 
 
 W, 
 
 Fig. 12. — Funnel for filling fruit 
 and sirup into jars. 
 
 PLUMS 
 
 This fruit is canned whole. On ac- 
 count of the high acidity of the 
 plum, glass is to be preferred to tin. 
 
 The fruit should be picked when 
 it is beginning to turn soft. As with 
 apricots, blanching before canning 
 is desirable. Pack in cans or jars and 
 add a medium or heavy sirup. See 
 table 1 for sterilization; or prepare and pack as shown in figures 14 
 and 15. Some plums are freestone in character, and such varieties may 
 be halved and pitted before canning. 
 
 FRESH PRUNES 
 
 Fresh California prunes are not canned commercially, but are per- 
 haps preferable to dried prunes for home use. Select well-colored ripe 
 prunes of large size. Wash and place in cans. Add medium sirup (40 
 per cent) hot. See table 1 for sterilization. 
 
 CHERRIES 
 
 Cherries canned without pitting develop a "bitter almond" or "pit" 
 flavor, pleasing to some and disagreeable to others. Inexpensive, small 
 
28 
 
 University of California — Experiment Station 
 
 hand-pitting machines can be obtained from most hardware stores 
 (fig. 13). The Royal Anne (Napoleon), a large white cherry, is seldom 
 pitted. Cherries tend to shrivel in heavy sirups or if the sirup is added 
 hot. Only moderately sweet sirups should be used, therefore, and the 
 cans exhausted by heating in boiling water or steam for 5 minutes before 
 sealing. See table 1. To save sugar, pitted cherries may be packed as 
 shown in figures 14 and 15. 
 
 Fig. 13. — Small hand-power cherry pitting machine for home use. 
 
 STRAWBERRIES, BLACKBERRIES, LOGANBERRIES, AND 
 RASPBERRIES 
 
 Strawberries, blackberries, loganberries, and raspberries shrink dur- 
 ing cooking and the fruit which fills a can when fresh will shrink to about 
 two thirds or less after sterilizing. If the cans are to be well filled, the 
 berries must first be cooked. The general procedure for precooking and 
 subsequent canning is illustrated on pages 33 and 34. 
 
 To each pound of fruit add 1 pound or less of sugar, according to the 
 ripeness of the fruit. Boil with gentle stirring for 3 to 4 minutes. Pack 
 into cans or jars, scalding hot. Seal cans. Sterilize cans at the boiling 
 point for 5 minutes. Glass jars or lacquered cans must be used for all 
 berries, because plain tin bleaches the color of the fruit. The extra sirup 
 formed by the juice of the fruit can be used on the next lot or the excess 
 
Cm. 276] Home Canning 29 
 
 moisture may be boiled off and the fruit made into a preserve before 
 canning. 
 
 An alternative method is to cook with sugar, as directed, and store 
 overnight to allow the berries to absorb excess sirup. Next day heat to 
 boiling, and proceed as above. 
 
 CURRANTS, CRANBERRIES, AND GOOSEBERRIES 
 
 These fruits are used only for pies, jellies, and jams, and are not com- 
 monly canned. They may be put up in enameled cans or in jars in plain 
 water and sterilized at 212° F for 10 minutes. No sugar need be used, 
 although the flavor of the fruit is better if canned in sirup instead of 
 water. (See table 1.) An alternative method is to convert them to sauce 
 or jam; can or pack hot in jars, and sterilize 10 minutes at the boiling 
 
 point. 
 
 GRAPES 
 
 Muscat and seedless grapes are canned commercially in considerable 
 quantities in California. The grapes are removed from the stems and 
 graded for size and appearance. Pack in cans or jars and add medium 
 or light sirup. The canned fruit is used for pies. (See table 1.) Tokay 
 grapes may be canned in the spiced sirup given for peaches. 
 
 FIGS 
 
 The fruit should be used firm-ripe and must be handled carefully 
 during picking and transferring to the cannery. 
 
 In commercial canning, figs are graded, washed, and then blanched 3 
 to 4 minutes in hot water. They are then placed in the cans in a very 
 heavy sirup (60° Balling) and are cooked in the sealed cans for about 
 2 hours at the boiling point. This method may be used in the home also 
 (see table 1). Or they may be packed as shown in figures 14 and 15, but 
 must be sterilized for 1% hours in the jar at the boiling point. 
 
 RHUBARB 
 
 Prom a culinary point of view, rhubarb is like a fruit and is very 
 easily sterilized and canned in the same general way as fruits. Since it 
 is used chiefly as pie stock no sugar need be used. 
 
 Wash the stalks, cut into short lengths, and place in a stewpan with 
 a little water. Boil until soft. Pack boiling hot into cans or jars and 
 seal. See table 1 for sterilizing time. Some prefer to cook the rhubarb 
 with about 1 cup of sugar to 2 cups'of rhubarb before canning. 
 
 Tin cans are soon badly corroded by rhubarb and only glass should 
 be used. 
 
30 University of California — Experiment Station 
 
 GRAPEFRUIT 
 
 Grapefruit is now canned in large quantities in Puerto Rico and 
 Florida. Use only thoroughly ripened fruit. Peel. Separate the segments 
 and peel these. Pack the peeled segments into jars or cans. Add a boiling 
 hot sirup of 50° Balling. See table 1 for sterilization. 
 
 FRUITS WITHOUT SUGAR 
 
 To pack fruits without sugar place the prepared fruits in jars or cans. 
 Fill with hot water and proceed as directed for canning fruits with 
 sirup. Sterilize as directed in table 1. 
 
 JELLY JUICES 
 
 Boil jelly fruits as for jelly making. Berries and currants are crushed, 
 boiled 5 minutes without addition of water. Apples are sliced without 
 previously peeling; enough water is added to prevent scorching and the 
 fruit is boiled until soft, usually 15 to 20 minutes. Press the boiled fruit 
 and strain the juice. Heat the juice to boiling ; pack into scalded jars 
 and sterilize as directed in table 1. Cans are not recommended for jelly 
 juices made from red fruits but are satisfactory for apple and other 
 white juices. 
 
 Crown-capped bottles may be used instead of jars if desired. (See 
 Extension Circular 65, cited in footnote 5.) 
 
 To use the jelly juice at a later date simply drain the juice carefully 
 from the sediment in the jar, add the customary amount of sugar, and 
 boil until the jellying point is reached. 
 
 FRUIT JUICES 
 
 See Extension Circular 65 (footnote 5, p. 4) for the preparation and 
 preservation of fruit juices in the home, and Circular 344 e for the com- 
 mercial preparation of fruit juices. 
 
 RIPE OLIVES 
 
 The Mission variety is best for home pickling, although the Manza- 
 nillo is also fairly satisfactory. The Sevillano and Ascolano varieties are 
 very difficult to pickle and should not be used by those unfamiliar with 
 the pickling of ripe olives. 
 
 Picking. — Pick the olives after they have acquired a light pink to red 
 color, and, if possible, before they have become jet-black and overripe. 
 Avoid bruising and prolonged storage in boxes before pickling. 
 
 9 Joslyn, M. A., and G. L. Marsh. Utilization of fruit in commercial production of 
 fruit juices. California Agr. Exp. Sta. Cir. 344:1-63. 1937. 
 
Cm. 276] Home Canning 31 
 
 Holding Solution.— It, for any reason, it is necessary to ship the olives 
 a great distance or to store them for a week or longer before pickling, 
 cover them in suitable containers with a 5 per cent salt solution (about 
 4% pounds of salt to 10 gallons) for 3 or 4 days. Then cover them with 
 a brine of about 12 per cent salt (about 12% pounds of salt to 10 gallons 
 of water) and keep the olives submerged in this solution until used. 
 However, the olives will usually be pickled direct from the tree. 
 
 Two-Lye Process. — The first lye treatment is to facilitate darkening 
 of the color. Prepare a lye solution of about 1% to 1% per cent ; this is 
 approximately 1% to 2 ounces of granulated lye per gallon of water, 
 or approximately % to % pound to 5 gallons of water. If the olives are 
 tender, use not more than 1 ounce of lye per gallon of water. 
 
 Cover the olives in a stoneware jar or wooden container with this lye 
 solution. Never use galvanized iron containers for the zinc of the coating 
 is dissolved by the lye and renders the olives poisonous. Stir every half 
 hour and carefully observe the progress of the lye action. The color of 
 the skins will change as the lye penetrates the olives. Cut two or three 
 olives lengthwise occasionally and when it is observed that the lye has 
 penetrated through the skins of practically all of the olives and a short 
 distance (% 4 to % 2 inch) into the flesh of some of them, remove and 
 discard the lye solution. With lye at 60° to 65° F the time required is 
 usually 4 to 6 hours. With tender-skinned olives or at higher tempera- 
 tures less time may be required, and with tough-skinned olives and lower 
 temperatures more time. 
 
 Leave the olives in the jar or tub and stir three times daily to facilitate 
 darkening of the color by oxidation. In order to avoid bruising, large 
 tubs of olives may be filled with water at the time of stirring and the 
 water drawn off after stirring. In small containers the fruit may be 
 stirred with the hands without adding water. Normally, 4 to 5 days' 
 exposure to air is required to give the desired color. 
 
 The second lye treatment is to remove bitterness. Prepare a solution 
 of 1 ounce of lye per gallon of water and place it on the olives. Stir them 
 occasionally (about once an hour) . Cut two or three olives now and then 
 and carefully observe the lye action ; it causes the flesh to darken slightly 
 in color; or, a drop of phenolphthalein solution (a small bottle of which 
 may be obtained at the drug store) will develop a red color to the depth 
 of the lye penetration. If this solution is used, rinse the lye from the 
 olives in water before cutting them for the test. Leave the olives in the 
 lye solution until it completely reaches the pits of the fruit (usually 8 
 to 16 hours at 60° to 65° F ) . If the lye fails to reach the pits in 24 hours, 
 replace it with a fresh lye solution. 
 
32 University of California — Experiment Station 
 
 When the lye has reached the pits of the olives remove and discard it. 
 Cover the olives with water and leave them submerged. 
 
 Change the water three times daily until all taste of lye is removed 
 or until the cut surface will no longer cause the test solution (phenol- 
 phthalein) to turn red or pink. Normally, 7 days' soaking in water is 
 required. 
 
 Curing in Brme. — The olives at this stage are edible but require salt 
 to bring out their flavor. Store the olives for 3 days in a brine of about 
 4 ounces ( Vi pound) of salt per gallon of water. They are then ready for 
 serving or canning. 
 
 Canning and Sterilizing. — Pack into cans or jars. Add boiling hot 
 brine of 4 ounces (% pound) of salt per gallon. Seal the cans. Place the 
 scalded rubbers and caps on the jars. 
 
 Sterilize as directed for vegetables in a pressure cooker at 240° F for 
 60 minutes (10 pounds' steam pressure). 
 
 The State Board of Health has ruled that all olives offered for sale 
 must be sterilized in this manner under the personal supervision of a 
 state inspector. 
 
 Color. — Attaining a black color is difficult and is largely a matter of 
 skill and experience. Even in commercial olive canneries much of the 
 fruit after pickling is brown rather than black in color. The brown fruit 
 is equally as nutritious as the black and usually of better flavor. Brown 
 color is usually due to too severe lye treatment. 
 
 One-Lye Process. — The preceding process produces olives of dark 
 color. If this color is not desired, a lighter-colored product of superior 
 flavor may be prepared by a single treatment. 
 
 In using this process, cover the olives with a lye solution of 2 per cent 
 (2% ounces of lye per gallon of water) and allow it to stand with occa- 
 sional stirring until the lye penetrates completely to the pit, normally 
 9 to 15 hours. 
 
 Remove the lye. Cover the olives with water. Change the water three 
 times daily until all taste of lye is removed (6 to 7 days). 
 
 Cure in brine, can, and sterilize as directed for the two-lye process. 
 
 Preserving Olives by Brine. — Instead of canning and sterilizing, the 
 olives may be kept several months as follows : After pickling, store them 
 one week in a brine of % pound of salt to the gallon. Then store in a 
 fresh brine of % pound of salt per gallon for one week. Similarly one 
 week in a brine of % pound of salt per gallon. Then store, until used, in 
 a brine of 1 pound of salt per gallon, changing the brine once a month ; 
 store in a cool place. When the olives are to be used soak a small quan- 
 tity overnight in water to remove excess salt. 
 
Cm. 276] 
 
 Home Canning 
 
 HOT PACK TO SAVE SUGAR AND JARS 
 
 In figures 14 and 15 are given in illustrated form full directions for 
 packing fruits without sugar or with little sugar by the hot-pack method. 
 
 Preparation of the fruit. — 
 Wash, sort, and prepare the 
 fruit as for cooking. Eemove 
 peel, cores, and pits; cut or 
 slice as desired. Cook as soon 
 as possible after cutting. To 
 prevent darkening, cut apples 
 and pears should be kept in 
 water until cooked. 
 
 Heating and cooking with 
 sugar. — Place the prepared 
 fruit in a pot and then add 
 dry sugar, *4 to % pound 
 per pound of fruit, or with 
 very sweet fruit, none. Add 
 a little water to firm fruits 
 to avoid scorching. Add no 
 water to berries. Heat to 
 scalding temperature. Do not 
 cook till soft. Peaches, pears, 
 cherries, grapes, and some 
 other firm fruits may be 
 cooked longer than berries or 
 soft fruits. 
 
 Filling the jars. — Warm 
 the jars with hot water, and 
 ladle the hot fruit into them 
 through a funnel until they 
 are filled to within ^ inch 
 of the top. Avoid getting 
 juice on the outside. The 
 neck should be dry and clean. 
 Or pack uncooked firm fruits 
 into jars cold. Add boiling 
 water or hot sirup and pro- 
 ceed as directed on next page. 
 
 Fig. 14. — Preparing fruits for modified hot-pack 
 process. This method allows more fruit per jar. 
 
34 
 
 University of California — Experiment Station 
 
 Placing rubbers and covers. 
 — Test clean, scalded rub- 
 bers by bending and stretch- 
 ing. They should not crack. 
 Put evenly in place on the 
 necks of the jars, then apply 
 the covers, placing or screw- 
 ing them loosely; then lower 
 the jars into the sterilizer, 
 placing a piece of wire screen- 
 ing or other false bottom in 
 the bottom of the boiler. 
 
 Sterilizing in a wash boiler. 
 — Have a few inches of hot 
 water around the jars. Apply 
 the cover of the boiler. Un- 
 less the cover fits very well 
 place a cloth beneath it. 
 Heat until steam comes freely 
 from beneath the cover and 
 then in addition for the time 
 specified in table 1. 
 
 Removal from the boiler. — 
 Eemove immediately. Han- 
 dles on the wire screen bot- 
 tom or wire baskets to hold 
 the jars facilitate removal. 
 A cloth or a wire jar lifter 
 may be used. The lifter in 
 the illustration serves well 
 for lifting jars and as a 
 false bottom. Place hot jars 
 on wood or paper to avoid 
 cracking. 
 
 Fig. 15. — Sterilizing and sealing jars of fruit. 
 
 Tightening the covers. — 
 Tighten the covers imme- 
 diately and stand the jars up- 
 side down. This insures the 
 sterilization of the covers. 
 Leaky jars can be detected 
 by air bubbles entering dur- 
 ing cooling. Do not invert 
 Economy jars or Kerr "self- 
 sealing" jars. 
 
Cir. 276] Home Canning 35 
 
 SPECIAL DIRECTIONS FOR VEGETABLES 
 
 Most vegetables have only a small amount of acid as compared with 
 fruits. This low degree of acidity, as we have seen, permits the growth 
 of certain bacteria which are very difficult to kill by heating. Vegetables, 
 therefore, are hard to sterilize. Tomatoes, which resemble fruit in 
 acidity, are an exception. 
 
 Usually in sterilizing vegetables temperatures above 212° F are neces- 
 sary. This requires the use of a steam-pressure cooker. The oven method 
 is very unsafe and dangerous. Either cans or jars may be used for vege- 
 tables. If jars are used it is recommended that they be filled with the 
 scalding hot vegetable and boiling hot brine. Then heat jars in boiling 
 water or live steam for 10 minutes for peas, string beans, asparagus, 
 carrots, beets, and other loosely packed vegetables ; and 15 to 20 minutes 
 for spinach, corn, sweet potatoes, and other tightly packed products. 
 Then seal the jars, place them in the pressure cooker and sterilize for 
 time given in table 2. 
 
 Where a pressure sterilizer is not available, it is advised that vege- 
 tables be dehydrated or pickled in brine. If properly acidified, vegetables 
 can be sterilized safely in jars or cans in boiling water; but this method 
 is recommended only for commercial canneries or such community can- 
 neries as are supervised by some one with technical training. In such 
 cases, directions may be obtained from the Fruit Products Division, 
 University of California, Berkeley. A leaflet describing the construction 
 and operation of an inexpensive home-sized evaporator for fruits and 
 vegetables and another giving directions for pickling vegetables in brine 
 are obtainable free of charge from the Agricultural Extension Service, 
 College of Agriculture, Berkeley. 
 
 ARTICHOKES 
 
 Young artichokes only are used. The hard tip is trimmed off and 
 some of the outer bracts removed, leaving only the tender parts. 
 
 They are blanched for 5 minutes in boiling water, acidified with % 
 measuring cup of lemon juice or vinegar per gallon, placed in cans or 
 jars, and covered with hot brine made of 3 level tablespoons of salt, % 
 cup of vinegar or lemon juice, and 1 gallon of water. Unless only a few 
 artichokes are to be canned it will be desirable to make up fresh brine 
 to be added to the jars, rather than to use the liquid from blanching, 
 for this will be cloudy and is apt to be disagreeable in flavor. For steri- 
 lization see table 2. During the present emergency it would seem good 
 policy to can more nutritious vegetables than artichokes, such as peas, 
 corn, and green beans. 
 
36 University of California — Experiment Station 
 
 ASPARAGUS 
 
 Green asparagus is of higher nutritive value than the white, but either 
 green or white is satisfactory for home canning. Grade into large, 
 medium, and small sizes. Cut into lengths to fit the container. This is 
 conveniently done by making a small box % inch less than the depth of 
 the can or jar and open at the top and one side. The bud ends of the 
 stalks are placed in the box against the closed end and the butts pro- 
 trude from the open end. They may be cut off flush with the edges. 
 
 Blanch in boiling water for about 4 minutes. Pack into jars or cans 
 with the tips up. Fill with hot brine. Heat jars 10 minutes in boiling 
 water. Seal cans or jars. Sterilize as directed in table 2. 
 
 GREEN BEANS 
 
 Green beans are best for canning when very young and tender ; the 
 larger and harder the pods and beans become, the lower their value for 
 canning. Commercially, beans are usually put up in no. 2 cans. 
 
 Snip or string after sorting. The larger sizes should be cut into pieces 
 about IV2 inches long, while the small no. 1 grade may be canned whole. 
 
 Blanch the no. 1 grade 2 minutes in a small amount of boiling water 
 and the larger grades for 5 minutes. Fill into cans or jars hot. Cover with 
 hot brine made of water in which the beans were blanched. Heat jars 10 
 minutes in boiling water. Seal cans and jars tightly. Place in pressure 
 sterilizer. Sterilize cans or jars as directed in table 2. 
 
 BEETS 
 
 Beets should be small and turnip-shaped if canned for market. The 
 first grade may be 1 to 1% inches in diameter and the second over 1% 
 inches. The large beets are quartered or sliced after peeling. 
 
 Scald in boiling water or in steam until the skin will slip easily, 
 
 usually about 15 minutes. Chill in cold water, peel, trim, and fill into 
 
 enamel-lined cans or glass jars. Fill cans with hot brine, and seal. Fill 
 
 jars with hot brine. Heat in boiling water 15 minutes. Seal. Sterilize as 
 
 directed in table 2. 
 
 CARROTS 
 
 Grade for size and color. Wash and scrape. Quarter lengthwise or cut 
 crosswise. Precook in a small amount of water 3 to 5 minutes in an un- 
 covered pan. Pack. Cover with water in which they were cooked. Add one 
 teaspoon of salt to each quart jar. Heat jars in boiling water 10 minutes. 
 Seal. Place in pressure cooker. Sterilize jars or cans as directed in 
 table 2. 
 
Cm. 276] Home Canning 37 
 
 SWEET CORN 
 
 Only young tender ears of good varieties of sugar corn should be used. 
 The corn must be fresh if good results are to be expected. Husk the ears 
 and cut the corn from the cob. Make a sweetened brine of % pound 
 (one measuring cup) of sugar and 1% ounces (4 level tablespoons) of 
 salt to 1 gallon of water. Mix the corn with a small amount of brine 
 (enough to cover the corn) and heat in a pot to boiling. 
 
 Fill scalding hot into jars. Heat in boiling water 10 to 15 minutes. 
 Seal. Place in pressure cooker and sterilize as directed in table 2. Cans 
 are filled scalding hot, sealed at once, and sterilized as directed in table 
 2. Cool the cans in cold water after sterilizing. 
 
 PEAS 
 
 Picking and hulling peas by hand is a very slow process and not to be 
 recommended for commercial canning. Large canneries do the hulling, 
 grading, blanching, and filling of cans entirely by machinery. It is fea- 
 sible, however, to shell by hand enough peas for canning for home use. 
 Use only fresh, tender peas. 
 
 Place the shelled peas in a small amount of water and boil long 
 enough to wrinkle the skins slightly, usually about 2 to 4 minutes, ac- 
 cording to the size and tenderness of the peas. 
 
 Fill into cans or jars and cover with the hot water in which they were 
 
 blanched. Add 1 teaspoon of salt and 3 of sugar to each quart jar or can. 
 
 Seal cans hot. Heat jars in boiling water 10 minutes. Seal. Sterilize as 
 
 directed in table 2. 
 
 PEPPERS, PIMIENTOS 
 
 These vegetables are usually peeled by causing the skin to separate by 
 roasting or by immersing in hot oil. They can be peeled successfully by 
 immersing from 2 to 3 minutes in cottonseed oil heated to smoking. They 
 are then chilled at once in cold water, and the skins come off easily from 
 the large peppers and pimientos. Small, pungent, tough-skinned Mexi- 
 can peppers do not yield so well to this treatment. When peeled in this 
 way, the peppers are soft and pliable and can be folded into the cans 
 after removing stems and seed cores. The peppers or pimientos may also 
 be peeled by roasting in a gas flame or in a very hot oven until the skins 
 will separate. 
 
 Pack the peeled product into cans or jars. Fill with boiling water or 
 brine. Sterilize in boiling water for 40 minutes. For the flavoring of stews 
 and other cooked dishes, it will be found that home dried peppers are 
 very satisfactory. See unnumbered wartime leaflet on drying foods in 
 the home. 
 
38 University of California — Experiment Station 
 
 NEW POTATOES 
 
 Peel, pack in jars or cans. Fill with dilute brine, containing 2 per cent 
 
 salt or about 1 level teaspoon per quart of water. Heat the cans in steam 
 
 or boiling water 5 minutes and seal them. Handle jars as with string 
 
 beans or peas. Sterilize quart and smaller containers at 240° F (10 
 
 pounds' pressure) for 40 minutes and 2 quart size jars, or no. 10 cans, 
 
 for 60 minutes. 
 
 PUMPKINS 
 
 Scrape out fibrous pulp and seeds, and cut the flesh and rind into 
 strips. Boil in water until soft. Scrape the flesh from the rind and press 
 through a colander. Boil to the desired consistency. Pack hot into cans 
 and seal. In using jars pack hot; heat jars in boiling water 20 minutes. 
 Seal. Sterilize in pressure cooker as directed in table 2. 
 
 TOMATOES 
 
 Tomatoes have a considerable amount of acid which checks the growth 
 of heat-resistant bacteria. They are, therefore, easily sterilized at 212° 
 F, and jars may be used satisfactorily. 
 
 For canning purposes, the variety used should be smooth and of a 
 deep-red color. Corrugated tomatoes are too difficult to peel. The San 
 Jose Canner and the Stone are excellent canning varieties. 
 
 Sort the tomatoes and reject those which are spoiled and underripe. 
 Place them in a blanching basket and immerse in boiling water long 
 enough to crack and loosen the skin, usually about % to 1 minute. Re- 
 move and chill in cold water. Slip off the skins and remove the cores. 
 Pack the tomatoes tightly into jars or cans and fill with juice ; or heat 
 to boiling in the juice obtained in coring, and pack tightly into cans 
 while hot, and seal. If packed cold in cans, the filled cans should be 
 heated in boiling water or live steam for 5 minutes before sealing. Steri- 
 lize as directed in table 1. Tomatoes grown in hot sections may require 
 longer sterilization, namely, 60 minutes in jars and 45 minutes in cans. 
 
 If the tomatoes are packed without the addition of juice, the produce 
 is known as "solid pack" ; if juice is added, as "standard pack." 
 
 Tomatoes may be canned whole to be used for slicing for salads, al- 
 though they will soften somewhat during sterilizing. Select small toma- 
 toes that will go into the jars or the cans. Cover with a hot tomato juice 
 pressed from crushed fresh tomatoes. Seal. Sterilize as directed in table 1. 
 
 Tomato Puree and Hot Sauce. — Tomato puree or sauce is very con- 
 venient for flavoring many dishes, such as stews, soups, and macaroni. 
 Cook tomatoes until soft. Rub through a fine screen to remove skins, 
 
Cir. 276] Home Canning 39 
 
 seeds, and fiber. Concentrate the puree to about one half its original 
 volume by boiling. Pack boiling hot into cans or jars and seal the cans. 
 Sterilize as directed in table 1. If a hot sauce is desired, add — according 
 to taste — salt, chopped onions, and hot peppers to the tomatoes before 
 cooking and screening. 
 
 Tomato Juice. — To retain vitamin C in home-canned juice, tomatoes 
 must be cooked before preparing the juice. Heat fully ripe tomatoes in 
 steam or boiling water until cooked through, usually 8 to 10 minutes. 
 Rub through a screen to separate the juice and red pulp from the seeds 
 and skins. Be sure to obtain most of the red pulp, because it contains 
 vitamin A. Pack hot in jars or cans and sterilize as directed in table 1. 
 Fuller directions for the home preparation and preservation of tomato 
 juice will be found in the wartime leaflet on fruit juices obtainable 
 from the Home Demonstration Agent in your county. (See also Exten- 
 sion Circular 65.) 
 
 SUMMER SQUASH AND ZUCCINI 
 
 Wash, trim, cut in pieces as for cooking. Blanch in boiling water 3 
 minutes. Pack. Fill with boiling water. Sterilize as directed in table 2. 
 
 SWEET POTATOES 
 
 Wash. Boil or steam until the skins will slip easily. Peel quickly and 
 pack hot. Fill the cans as tightly as possible, and seal. Or fill hot into 
 jars, heat in boiling water for 30 minutes, and seal. Sterilize in pressure 
 cooker as directed in table 2. After removal from sterilizer, cans should 
 be chilled at once in cold water, but jars are allowed to cool naturally. 
 
 SPINACH AND OTHER GREENS 
 
 Can as soon after picking as possible. Trim off stems and imperfect 
 portions. Wash thoroughly to remove all dirt. Heat in open pot with 
 very little water until well wilted. Fill scalding hot into jars. Salt the 
 water lightly in which cooked and add to jars. Heat jars in boiling water 
 10 to 15 minutes. Seal. Pack hot into cans ; fill with liquid as above ; 
 seal. Sterilize as directed in table 2. 
 
 OKRA 
 
 Okra, or gumbo, is grown frequently in the hot sections of the state 
 for flavoring soups, stews, and other dishes. The pods resemble green 
 peppers in appearance. 
 
 Use only the young, tender pods for canning. Remove the stems. 
 Blanch 6 to 8 minutes in boiling water. Pack into cans with boiling water. 
 Sterilize as directed in table 2. 
 
40 University of California — Experiment Station 
 
 CONCENTRATED SOUP MIXTURES 
 
 Vegetables such as carrots, onions, tomatoes, beans, etc., may be pre- 
 pared as for vegetable soup and canned. A recipe recommended by the 
 United States Department of Agriculture is as follows : 
 
 A good combination consists of 1 quart of screened concentrated tomato pulp 
 (boiled tomatoes screened and two volumes of pulp boiled down to one volume), 1 
 pint of green corn or tiny lima beans, 1 pint of okra or sweet peppers, 1 small onion 
 chopped, % cup of chopped sweet red pepper, iy 2 teaspoonfuls of salt, and 3 tea- 
 spoonfuls of sugar. Cook the tomatoes, pepper, and onion; put through a sieve to 
 remove seeds ; and cook down to about the consistency of ketchup. Measure, add the 
 corn or beans and okra, which have been prepared as for canning. Add the seasoning 
 and cook all together for 10 minutes. Pack at once into hot jars, and process 50 min- 
 utes at 240° F. Tin cans should be plunged immediately into cold water after process- 
 ing at 250° F for 40 minutes and cooled as quickly as possible. When cool, store in 
 a dark, dry, cool place. 
 
 If all of the vegetables recommended are not available, others may be 
 substituted, such as cooked white beans for corn, pimientos for okra, 
 white potatoes for lima beans. Celery makes a valuable addition to the 
 mixture. When used for soup the canned product is diluted with water 
 and flavored with bouillon cubes or meat broth. For convenience it 
 should be put up in small containers. 
 
 PRESERVATION OF MEATS 
 
 Meats, owing to their texture and absence of acidity, are even more 
 difficult to sterilize than vegetables. If incompletely sterilized, they may 
 be attacked by certain heat-resistant bacteria which produce dangerous 
 poisons. Because of this difficulty and danger, it is recommended that 
 in the home, meats and fish should be preserved by salting or by salting 
 and smoking, unless first done under the personal supervision of your 
 Home Demonstration Agent and according to mimeographed directions 
 obtainable from her. Directions for salting and smoking meats are given 
 in Farmers' Bulletins 1186 and 1415, obtainable free of charge on appli- 
 cation to the United States Department of Agriculture, Washington, 
 D. C. Directions for the salting and smoking of fish are obtainable from 
 the United States Bureau of Fisheries, Washington, D. C. However, 
 there is some danger of botulinus poisoning from improperly prepared 
 smoked fish. Therefore, home-smoked fish should never be tasted until 
 thoroughly cooked. See your Home Demonstration Agent for further 
 advice on the preservation of meats. It is also practicable to dry lean 
 meats free of fat in the home evaporator, as described in the wartime 
 leaflet on home drying of foods. It is also obtainable from your county 
 Home Demonstration Agent. 
 
Cir. 276] Home Canning 41 
 
 CONDENSED DIRECTIONS 
 
 Tables 1 and 2 give brief directions for preparation and safe periods 
 of sterilization for home-canned products. 
 
 Lengths of time for sterilizing in boiling water given in table 1 are 
 designed for altitudes from sea level to 1,000 feet. For altitudes above 
 1,000 feet, the length of sterilization in boiling water should be increased 
 about 20 per cent (one-fifth) for each additional 1,000 feet. See table 3. 
 
 Some pressure gauges are also affected by altitude; therefore, the 
 pressure indicated in table 2 should be increased 1 pound for each 2,000 
 feet increase in elevation. As stated elsewhere, it is recommended that 
 a thermometer be used on pressure sterilizers and that temperature, not 
 pressure, be used as a guide. Pressure gauges are often inaccurate after 
 long use. Thermometers retain their accuracy and are not affected by 
 altitude. Sterilize 2-quart-sized jars 1% times as long as quart jars. 
 
 VITAMINS IN CANNED FOODS 
 
 Until a few years ago it was considered that a satisfactory diet need 
 contain only proteins of suitable composition, carbohydrates (sugars 
 and starch), fats, inorganic salts, and water. At present, however, it is 
 recognized by all authorities on nutrition that in addition to these 
 necessary food constituents a complete diet must include the vitamins. 
 
 The vitamins are different from the other food constituents in that 
 they do not furnish energy nor form tissue, but serve in the utilization 
 of food in much the same manner that a spark plug serves an engine in 
 its utilization of gasoline. Vitamins are necessary not only for health 
 and vigor but for life itself. In the absence of vitamins normal growth 
 and life functions cease or become greatly altered. 
 
 Authorities differ to some extent in regard to the exact number of 
 vitamins and some of their properties, although most agree that the six 
 most important vitamins are those to which have been given the designa- 
 tions A, Bi, C, D, E, and nicotinic acid. The vitamin formerly designated 
 as F is at present termed B x . 
 
 Yitamm A. — If vitamin A is absent from the food, normal growth is 
 retarded and the general health is lowered. In experimental animals, 
 deficiency of this vitamin is evidenced by the onset of an eye disease, 
 xerophthalmia. Death ensues if the deficiency is severe and sufficiently 
 prolonged. Vitamin A is fat soluble and growth promoting. 
 
 It occurs in abundance in whole milk, butter, cod-liver oil, liver, ice 
 cream, and as carotene in most vegetables, both canned and uncanned. 
 It is very abundant in leafy vegetables, carrots, and in tomatoes. Prunes 
 
42 
 
 University of California — Experiment Station 
 
 table l 
 Condensed Directions for Canning of Fruits, Khubarb, Tomatoes, 
 
 AND PlMIENTOS 
 
 Variety 
 
 Preparation 
 
 Sirup* recommended 
 
 Minutes steriliza- 
 tion in boiling 
 water or steam 
 at 212° Ft 
 
 Quart 
 jars 
 
 Quart 
 
 cans 
 
 no. 2H 
 
 Apples 
 
 Apricots 
 
 Berries, all varieties 
 
 Cherries, sweet 
 
 Cherries, sour for pie 
 
 Figs (preserved) 
 
 Figs in sirup t 
 
 Grapes, Muscat and Seed 
 less 
 
 Peaches, clingstone, 
 Phillips Cling 
 
 Peaches, freestone and 
 Tuscan 
 
 Pears 
 
 Pimientos 
 
 Plums 
 
 Prunes, fresh 
 
 Rhubarb 
 
 Tomatoes§ 
 
 Tomato puree and juice. 
 
 Jelly juices 
 
 Fruit juices 
 
 Peel, core, quarter, and 
 blanch 3-4 minutes 
 
 Halve and pit; blanch in 
 medium sirup 3-4 minutes.. 
 
 Boil 3 minutes with equal 
 weight of sugar; stand 24 
 hours, pack hot 
 
 Stem; pit if desired 
 
 Stem and pit 
 
 Equal parts sugar, fruit, and 
 
 water cooked to preserves; 
 
 can hot 
 
 Sort and wash 
 
 Stem. 
 
 Halve, pit, and peel. 
 
 Halve, pit, and peel. 
 Peel, halve, and core. 
 
 Roast and peel 
 
 Sort, stem, and wash . 
 
 Wash, sort 
 
 Wash, cut, and stew until soft; 
 pack hot; no sugar 
 
 Scald, cool, dip, peel, and core 
 
 Boil soft, screen, boil to H vol- 
 ume and can hot 
 
 Boil fruit; press and strain 
 juice as for jelly making ; can 
 hot 
 
 (See' Extension Circular 65). . . . 
 
 Water. 
 
 Medium or heavy; 40° 
 or 60°Bal 
 
 In own sirup 
 
 Medium or light; 40° 
 
 or20°Bal 
 
 Water 
 
 In own sirup . 
 Very heavy ; 6 
 
 -65°Bal. 
 
 Medium or light; 40° or 
 20°Bal 
 
 Medium or heavy; 40 c 
 or60°Bal 
 
 Medium or heavy; 40° 
 or60°Bal 
 
 Medium or light; 40° or 
 20°Bal 
 
 Water or light brine 
 
 Heavy or medium; 60° 
 or40°Bal 
 
 Medium; 40° Bal 
 
 In own juice. 
 In own juice. 
 
 In own juice. 
 
 In own juice. 
 
 15 
 
 25 
 
 15 
 
 60 
 120 
 
 20 
 
 35 
 
 25 
 
 20 
 
 50 
 
 120 
 
 30 
 
 20 
 
 15 
 
 * Sirups: for convenience, sirups are classified as: light, 1 cup of sugar to 4 of water; medium, 1 cup 
 of sugar to 2 of water; and heavy, l x A cups of sugar to 1 of water. 
 
 t For altitudes above 1,000 feet see table 3. 
 
 t Because of difficulty of sterilizing it is recommended that figs be dried or made into preserves or jam 
 instead of being canned. 
 
 § Tomatoes grown in hot areas usually require 60 minutes and 45 minutes, respectively, for jars and 
 cans. 
 
Cir. 276] 
 
 Home Canning 
 
 43 
 
 TABLE 2 
 
 Condensed Directions for Preparing and Sterilizing Vegetables and Olives 
 (For brines see special directions for each product) 
 
 Variety 
 
 Preparation 
 
 Minutes sterilization 
 
 at 240° F 
 
 CIO lbs. pressure) 
 
 for cans and jars* 
 
 Artichokes 
 
 Blanch 5 minutes in water with % cup vinegar per 
 gallon. Can in fresh brine of % cup of vinegar 
 and 3 tablespoons of salt per gallon of water 
 
 15 
 25 
 
 
 
 30 
 
 
 
 30 
 
 
 
 40 
 
 
 
 90 
 
 
 
 75 
 
 Olives, ripe 
 
 Pickle, as directed on page 31 
 
 60 
 
 
 
 40 
 
 
 
 40 
 
 Pumpkins and squash 
 
 Cut; remove seeds and "rag"; cook; scrape from 
 
 90 
 
 Summer squash and 
 
 Wash, cut, and blanch. Can in water 
 
 60 
 
 
 90 
 
 Vegetable soup mixture .... 
 
 See special directions, page 40 
 
 50 
 
 * The table is for no. 2 X A or smaller cans and for quart or smaller jars. For no. 10 cans and 2-quart 
 jars increase the time by one half. Thus if the time for quart jars is 60 minutes use 60+30 or 90 minutes 
 for 2-quart jars. 
 
 TABLE 3 
 
 Approximate Sterilizing Times at Boiling Point at Various Altitudes* 
 
 Product 
 
 Minute? at boiling point at various elevations 
 in quart jars 
 
 0-1,000 
 
 feet 
 
 2,000 
 feet 
 
 3,000 
 feet 
 
 4,000 
 feet 
 
 5,000 
 feet 
 
 Apples 
 
 Apricots 
 
 Berries 
 
 Cherries 
 
 Figs, preserved 
 
 Figs, canned in sirup 
 
 Grapes, Muscat and Seedless 
 
 Peaches, Phillips Cling 
 
 Peaches, free and Tuscan. . . 
 
 Pears 
 
 Pimientos 
 
 Plums 
 
 Prunes, fresh 
 
 Rhubarb 
 
 Tomatoes 
 
 Tomato puree 
 
 Jelly juices 
 
 15 
 
 25 
 15 
 30 
 60 
 120 
 20 
 35 
 25 
 30 
 40 
 20 
 30 
 15 
 30 
 20 
 15 
 
 18 
 30 
 18 
 35 
 70 
 145 
 25 
 40 
 30 
 35 
 50 
 25 
 35 
 18 
 35 
 25 
 18 
 
 21 
 35 
 21 
 40 
 80 
 165 
 30 
 48 
 35 
 40 
 60 
 30 
 40 
 21 
 40 
 30 
 21 
 
 24 
 40 
 24 
 45 
 90 
 190 
 35 
 55 
 40 
 45 
 70 
 35 
 45 
 24 
 45 
 35 
 24 
 
 45 
 
 27 
 50 
 100 
 215 
 40 
 60 
 45 
 50 
 80 
 40 
 50 
 27 
 50 
 40 
 
 * The times given in the table are for quart jars. For no. 2 1 A cans use 3 minutes less than the times 
 given in the table. For no. 10 cans and for 2-quart jars increase the times by one-half; thus if the time for 
 quart jars is 20 minutes use 20+10, or 30 minutes, for 2-quart jars. 
 
44 University of California — Experiment Station 
 
 and apricots are also sources of vitamin A. Canning and sterilizing do 
 not materially reduce its potency; thus canned vegetables, such as 
 spinach and tomatoes, are practically as rich in this vitamin as the cor- 
 responding fresh vegetables. Drying reduces somewhat the quantity of 
 vitamin A in vegetables, but the dried vegetables still retain much of 
 their original content of vitamin A. This vitamin differs generally from 
 the others in that it is stored in the body, particularly in the liver, for 
 future use. 
 
 Vitamin B ± . — A common disease in the Orient, beri beri, is caused by 
 lack of vitamin B x . Kice prepared for the market is polished ; that is, 
 the bran is removed mechanically and with the bran goes this vitamin. 
 The discovery of the relation of this disease to the lack of some constitu- 
 ent of the rice bran led to extensive investigations on this, as well as 
 other vitamins. A diet poor in vitamin B x causes loss of appetite, consti- 
 pation, loss of weight, and a tired feeling. 
 
 Fowls are used as experimental animals in studies on vitamin B x be- 
 cause they soon develop polyneuritis (paralysis) when this vitamin is 
 withheld from the diet. Addition of foods rich in vitamin B t to the diet 
 of fowls so affected causes recovery (if the disease is not too far ad- 
 vanced). Beri beri can be cured in similar manner. 
 
 Vitamin B t occurs in vegetables, bran and germ cells of cereals, and 
 in most other natural foods. Yeast is a rich source of this vitamin. Gar- 
 den greens, spinach, raw cabbage, and canned tomatoes contain a con- 
 siderable amount of it. Vitamin B ± is somewhat more susceptible to the 
 destructive action of heat under pressure than vitamin A, and consider- 
 able destruction of B 1 occurs during sterilization in a pressure cooker. 
 Drying apparently lowers the activity of vitamin B ± in vegetables only 
 slightly. Not so much attention has been given to the study of this vita- 
 min in fruits as in vegetables, but in the experiments thus far reported 
 canning of fruits does not materially lower their content of this vitamin. 
 Fresh fruits are generally lower than vegetables in vitamin B x and a 
 considerable portion of it is destroyed during sterilization under pres- 
 sure. 
 
 Vitamin C. — Scurvy is caused by lack in the diet of vitamin C. It has 
 long been known that the use of limes, lemons, oranges, and fresh or 
 canned vegetables would prevent and cure scurvy. Oranges and lemons 
 are superior to limes in vitamin-C content. British sailing vessels carried 
 lime juice as a preventive long before it was known that there was such 
 a thing as vitamin C. The name "lime juicer" still sticks to British sail- 
 ing vessels. Scurvy was the scourge of early polar expeditions. 
 
 This vitamin occurs in abundance in citrus fruits, some vegetables 
 
Cir. 276] Home Canning 45 
 
 such as fresh spinach and raw cabbage, and to some extent in root vege- 
 tables such as potatoes and carrots, both fresh and canned. Orange juice 
 is widely used, particularly as a part of the diet of infants, because of 
 its high content of vitamin C. 
 
 Vitamin C is sensitive to the combined action of heat and oxidation, 
 that is, action of the air, and under certain conditions much or most of 
 the vitamin is lost in canning. However, the vitamin C of tomatoes, of 
 citrus juices, and of most other acid fruits is well retained in spite of the 
 usual processes of sterilization and pasteurization. 
 
 Since the vitamin is so sensitive to oxidation, ordinary drying proc- 
 esses destroy most of the vitamin C of unsulfured fruits. Sulfuring 
 fruits before drying prevents loss of vitamin C. Where possible, it is, 
 therefore, desirable to use the fresh fruits, oranges being one of the best 
 known sources of this vitamin. Canned tomatoes may also be used where 
 fresh fruit is not obtainable. As vitamin C is not stored in the body some 
 of it should be eaten every day. 
 
 Vitamin D. — Lack of vitamin D causes rickets, a well-known disease 
 of the bones of improperly nourished children. The bones become soft 
 and bend easily. Rickets is characterized by lack of development of 
 bone tissue. Calcium and phosphorous are not properly assimilated in 
 building bone when D is lacking. 
 
 Cod-liver oil is extremely rich in this vitamin and is, along with sun- 
 light, the classic remedy and preventive for rickets. Milk and milk fat 
 contain considerable vitamin D and egg yolk is also a very good source of 
 this vitamin. Its presence in leafy vegetables has also been demonstrated. 
 
 Vitamin D is very resistant to the action of heat, oxidation, and chemi- 
 cals. Cooking of foods in which it is found apparently does not noticeably 
 lower its potency. 
 
 That sunlight can take the place of this vitamin in preventing and in 
 curing rickets has been well proved. A common practice now is to expose 
 infants to sunshine as a regular part of their care. Irradiation of the 
 skin with ultraviolet light is also effective. The vitamin-D content of 
 milk and of vegetable oils can be greatly increased by exposure to ultra- 
 violet light, recent investigations show. 
 
 Vitamin E. — Vitamin E is rather widely distributed in foods, but is 
 particularly abundant in leafy vegetables and in the germs of cereals. 
 So far as is known it is not lacking in the average human diet. In experi- 
 mentally fed rats sterility may be induced by withholding it from the 
 diet, that is, the animals lose their power of reproduction. 
 
 It is very resistant to heat, oxidation, and chemical reagents. Canning 
 and drying probably do not affect its activity. 
 
46 University of California — Experiment Station 
 
 Nicotinic Acid. — This vitamin prevents and cures pellagra, a disease 
 prevalent in the southern states Milk, greens such as spinach, some 
 fruits, and probably fresh meats, are believed to be good sources of this 
 vitamin. It has been discovered only recently and its occurrence in va- 
 rious foods has not been thoroughly determined. It is very resistant to 
 heat and oxidation. If present in the fresh food it is fully retained in the 
 canned. It is classed as a part of the vitamin-B complex. 
 
 Summary of Vitamins. — Vitamins are essential food factors required 
 for normal development and nutrition. With the exception of vitamin 
 Bi and vitamin C, and this only in part, canning does not appreciably 
 affect their potency. Canned fruits, tomatoes, and most canned vege- 
 tables are rich sources of the various vitamins. Certain canned foods are 
 richer than others in certain vitamins; therefore, in order to supply all 
 of the vitamins, as well as to provide a balanced diet in other respects, 
 it is wise to include in the family diet a variety of fruits and vegetables, 
 canned, dried, and fresh. 
 
 FOOD POISONING 
 
 (Prepared by Dr. K. F. Meyer, Director of the G. W. Hooper Foundation, Univer- 
 sity of California, and by Dr. J. C. Geiger, Director of the Department of Health, 
 City of San Francisco, California.) 
 
 Food poisoning, as it is understood today, is the result, directly or 
 indirectly, of the contamination of food with certain bacterial organ- 
 isms, and clinically it may be classified as an intoxication. Intoxication 
 in this instance refers to poisoning by bacterial toxin ; not to alcoholic 
 intoxication. However, in the consumption of food contaminated with 
 the paratyphoid group of bacteria, infections may occur. 
 
 With the growth of scientific knowledge regarding the specific dangers 
 of contaminated food, there has been a more intelligent appreciation on 
 the part of consumers and of health officials of the comprehensive meas- 
 ures that have usually been adopted for control in the distribution, 
 handling, and processing of food whether it is canned or not. Food 
 poisoning is probably as old a condition as any of those diseases affecting 
 the human being and consequently has been known by a much varied 
 terminology. Ptomaine poisoning, ice-cream poisoning, tinned-food poi- 
 soning, sausage poisoning, cheese poisoning, and meat poisoning, or any 
 other particular kind of food poisoning suspected, have been given as 
 the cause of different outbreaks, usually, without epidemiologic, bacteri- 
 ologic, or toxicologic investigation. The foods that can be directly classi- 
 fied and identified with poisonings of nonbacterial nature are mush- 
 rooms, mussels, and certain others. 
 
Cm. 276] Home Canning 47 
 
 This descriptive terminology undoubtedly has led to a complexity of 
 diagnosis, which has been further complicated by the recognition that 
 certain preserved foods can contain a most virulent and thermolabile 
 toxin, causing as a result when ingested, the so-called botulinus intoxi- 
 cation. Experience has taught that in the United States, outbreaks of 
 food poisoning due to bacteria other than botulinus are fairly common. 
 A careful laboratory examination of material from typical outbreaks 
 has shown that the new type of food poisoning due to the toxic products 
 of the staphylococcus is much more frequently encountered than has 
 formerly been believed. Poisoning cases of food infections due to the 
 paratyphoid or salmonella bacilli are relatively rare. 
 
 The recognition of these types of food poisoning, clinically, should 
 present very little difficulty, whether the condition is due to food con- 
 taminated with the staphylococcus group, with the paratyphoid group, 
 or with the toxin of Bacillus botulinus, since each causes totally dis- 
 similar symptoms. The laboratory procedure incident to the isolation 
 of the staphylococcus or the paratyphoid group from the toxin of B. 
 botulinus in foods is technically well known, The method for deter- 
 mination of the presence of B. botulinus toxins is also well known to 
 laboratory technicians. Therefore, the investigative problem is com- 
 paratively simple. However, in the majority of the outbreaks recorded, 
 the well-known facts mentioned above are overlooked either because of 
 the limited duration of the illness or because of incomplete epidemio- 
 logic, bacteriologic, or toxicologic investigation. 
 
 It is deemed important to point out briefly in the accompanying table 
 the different investigative procedures that are suggested in outbreaks, 
 and the clinical symptoms in both types of food poisoning. 
 
 Never taste spoiled canned food. Suspicious jars or cans of food, that 
 is, those which possess a disagreeable odor or show gas pressure, should 
 be destroyed without tasting. The contents of such jars should be mixed 
 with several spoonfuls of lye, and jar and contents buried. Suspected 
 material should be destroyed and not fed to chickens or animals. Many 
 cases are on record in which large numbers of chickens have been killed 
 by eating spoiled canned foods. Human cases of fatal poisoning have 
 resulted from merely tasting spoiled cans of food. Report at once all 
 such types of illness to your family physician 10 and to the local health 
 officer. The following table is largely for his guidance ; call his attention 
 to it at once in cases of suspected food poisoning. 11 
 
 10 It is also suggested that he immediately notify the Hooper Foundation for 
 Medical Research, Second and Parnassus Avenues, San Francisco, California. 
 
 u As first-aid treatment give an emetic and an enema or purgative to eliminate 
 from the system as much of the unabsorbed toxin as possible. 
 
TABLE 4 
 
 Comparative Procedures in Cases of Food Poisoning 
 (For gnidance of physicians or health officers) 
 
 General Food Poisoning 
 
 Botulism 
 
 incubation period 
 
 Usually 2 to 4 hours, staphylococcus 
 toxin. If over 12 hours, salmonella 
 bacilli. 
 
 Usually 24 to 38 hours. 
 
 TREATMENT 
 
 Supportive and eliminative. 
 
 Botulinus antitoxin, specific type; 
 give both A and B antitoxin; absolute 
 quiet; eliminative. 
 
 investigation procedure 
 
 4. 
 
 Use incubation period for basis of de- 
 termining the causative meal. 
 
 Always suspect freshly cooked or 
 warmed-over foods, cakes, pastry, 
 minced meats, etc. Preserved foods 
 are rarely at fault. The foods are 
 usually all right as to taste, ap- 
 pearance, odor, and texture. 
 
 Bacteriologic. examination of excreta 
 of patients and the suspected food 
 for the salmonella group, staphylo- 
 coccus group, and other organisms. 
 
 Bacteriologic and epidemiologic 
 search for human carriers and pos- 
 sible contamination from animal 
 sources. 
 
 Complications: appendicitis, chole- 
 cystitis, persistant elevation of 
 temperature (paratyphoid infec- 
 tion). 
 
 1. Use incubation period for basis of 
 
 determining the causative meal. 
 
 2. Always suspect preserved foods; 
 
 likewise, meat products such as 
 sausages. Spoilage of food is 
 noted in many instances. 
 
 3. Test suspected food for toxin by 
 
 animal inoculation; mice, guinea- 
 pigs, or rabbits. Test for type with 
 specific antitoxin. Cultures of sus- 
 pected food for the presence of 
 spores, particularly if food has 
 been previously boiled. 
 
 4. Search for domestic animals, such 
 
 as chickens with symptoms of 
 limberneck for corroborative field 
 and laboratory evidence. 
 
 5. Complications: bronchopneumonia. 
 
 6. Human outbreaks are usually due 
 to type-A toxin, occasionally to 
 jtype B. 
 
 SYMPTOMATOLOGY 
 
 Sudden onset; nausea, vomiting, ab- 
 dominal pain, prostration, diarrhea, 
 and rise of temperature. 
 
 Mortality, to 1 per cent. 
 Case infectivity rate high. 
 
 Delayed onset; marked muscular weak- 
 ness; gastro-intestinal symptoms, 
 rare; disturbances of vision with 
 diplopia and blepharoptosis; loss of 
 ability to swallow and talk; consti- 
 pation; rapid pulse and subnormal 
 temperature; rarely any pain; death 
 from respiratory failure. 
 
 Mortality over 60 per cent. 
 
 Case infectivity rate usually 100 per 
 cent. 
 
 30/n-8,'42(2270)