UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA PHYSICAL AND CHEMICAL PROPERTIES OF CALIFORNIA HONEYS J. E. ECKERT and H. W. ALLINGER BULLETIN 631 August, 1939 UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA CONTENTS PAGE Introduction 3 Definition of honey 4 How honey is produced 5 Methods of determination and analysis 7 Collection of samples 7 Determination of color 8 Determinations of weight and moisture 8 Chemical analyses 8 Tabulation of data 9 Some physical characteristics of honeys 9 Color 9 Weight per gallon 17 Granulation 19 Flavor 21 Analytical data 22 Moisture 22 Total sugars 22 Ash 23 Dextrin 24 Acid 24 Enzymes 24 Undetermined materials 24 Honeydew honeys 25 Summary 26 Acknowledgments 27 PHYSICAL AND CHEMICAL PROPERTIES OF CALIFORNIA HONEYS 1 J. E. ECKERT 2 and H. W. ALLINGER 3 INTRODUCTION The first honeybees were introduced into California in 1853, and since then the beekeeping industry in this state has grown to a position of first rank as compared to that in the other states. The present bee population of California is estimated at between 300,- 000 and 345,000 colonies, which produce from 12 to 22 million pounds of honey annually. The colonies are located primarily in the irrigated regions, where the bees render invaluable services in the pollination of fruit, vegetable, and seed crops. The length of the growing season in California and the wealth of the nectar and pollen plants in the cultivated and uncultivated regions of the state make it possible for beekeepers to practice a migratory system of beekeeping in order to keep the bees at work during the blooming periods of the many plants. This system of beekeeping tends to increase the production of surplus honey and to add greatly to the varieties of honeys that enter the commercial channels of trade. Migratory beekeep- ing also results in locating colonies in waste places and in often obscure mountain regions where they are rarely seen by the general public ; and this tends to conceal the magnitude of the industry as a whole. California has at least 175 species of plants of sufficient importance to be listed as yielders of pollen and nectar. 4 About 40 of these plants yield nectar in sufficient abundance during favorable seasons to produce com- mercial quantities of honey, but the great bulk of the honey in California comes primarily from a relatively small number of plants, such as the sages, alfalfa, citrus, cotton, yellow star thistle, California buckwheat, manzanita, and lima bean. While a majority of the important nectar- producing plants are uncultivated forms, made up mostly of native and introduced weeds, certain of the cultivated varieties also produce large quantities of honey and provide a very important source of pollen, which is essential to the well-being and development of the honeybee colony. Thus the deciduous fruit trees are valued by the beekeeper for the stimu- 1 Received for publication October 24, 1938. 2 Associate Professor of Entomology and Associate Apiculturist in the Experiment Station. 3 Analyst in the Division of Chemistry. 4 Vansell, G. H. Nectar and pollen plants of California. California Agr. Exp. Sta. Bui. 517:1-60. 1931. (Out of print.) [3] 4 University of California — Experiment Station lating effect the nectar and pollen from their blossoms have on the growth of the colony, rather than for the small amount of strongly flavored sur- plus honey occasionally produced. This is also true for many of the truck crops and especially the cucurbits, although in rare instances commer- cial quantities of honey are produced from such plants as the onion and asparagus when they are grown for seed in sufficient quantities. As a general rule, it is not practical to plant a given crop solely for the nectar or pollen produced, since bees have to range over too great an area to gather sufficient food for their own needs. 5 The greater portion of the honey produced in California is in the ex- tracted or liquid state, only a small quantity of the total being harvested in sections or in comb form. Honey to be extracted is stored by the bees in large combs, the cells of which are later uncapped by the beekeeper with a heated knife. The honey is extracted by centrifugal force in a special machine that does not injure the combs for further use. It is strained to remove particles of comb and allowed to remain in large tanks for several days until the air bubbles, incorporated in the extracting process, rise to the surface. The honey is then drawn into 5-gallon tin containers for the wholesale or bottling trades. Before honey is placed in retail containers, it is generally heated to retard granulation and to facilitate any further straining that may be necessary. Despite the fact that honey is one of the oldest forms of sweet known to man, there is a general lack of knowledge concerning its chemical and physical properties. The present studies were undertaken to supply this technical information about the more important California honeys. DEFINITION OF HONEY The Service and Regulatory Announcements of the Food and Drug Ad- ministration, United States Department of Agriculture, gives the follow- ing definition of honey : 1. Honey is the nectar and saccharine exudations of plants gathered, modified, and stored in the comb by honeybees (Apis mellifica and Apis dorsata), is levorotatory, and contains not more than 25 per cent of water, not more than 0.25 per cent of ash, and not more than 8 per cent of sucrose. 2. Comb honey is honey contained in the cells of comb. 3. Extracted honey is honey which has been separated from the uncrushed comb by centrifugal force or gravity. 4. Strained honey is honey removed from the crushed comb by straining or other 5 Eckert, J. E. The flight range of the honeybee. Jour. Agr. Research 47(5) : 257- 85. 1933. 6 United States Department of Agriculture Food and Drug Administration. Defini- tions and standards for food products. U. S. Dept. Agr. Food and Drug Service and Eegulatory Announc. F. D. 2:11. 5th rev. Nov., 1936. Bul. 631] Properties of California Honeys 5 The definition of honey in the Agricultural Code of California reads as follows : "Honey" means the nectar of floral exudations of plants gathered and stored in the comb by bees (Apis mellifica). It is levorotatory, contains not more than twenty (20) per cent of water, not more than twenty-five one-hundredths [0.25] of one per cent of ash, not more than eight (8) per cent of sucrose, its specific gravity is not less than 1.412, its weight not less than eleven (11) pounds, twelve (12) ounces per standard gallon of 231 cubic inches at sixty-eight (68) degrees Fahrenheit. 7 The chief discrepancies between these two definitions lie in the de- scriptions of the origin of honey and in the moisture content. The federal regulation is more inclusive in defining it as "the nectar and saccharine exudations of plants . . ." than the California code, which limits the source to "the nectar of floral exudations of plants. . . ." Certain honeys, such as cotton, are produced primarily from extrafloral nectaries and such would not be classified as true honeys under a strict interpretation of the words "floral exudations." The California Code places the maxi- mum water content at 20 per cent, the federal definition at 25 per cent ; furthermore, if the water content of honey is more than 20 per cent by weight, its specific gravity will be less than the requirement under the California regulations. HOW HONEY IS PRODUCED Although many are aware than honey is stored by the honeybee in combs from which it can be extracted by the beekeeper, there is still a difference of opinion as to how the nectar of flowers is converted by the honeybee into the finished product. Only a limited number of references on the chemical composition of nectar are available, but the researches of Planta, Kenoyer, Caillas, Beutler, Park, Vansell, 8 and others, indicate that the nectar of different flowers is variable in the content of moisture, sugars, minerals, proteins, and other substances. The moisture and sugar content are the most vari- able factors in nectar ; these differ not only with the plant but also with 7 [California] Agricultural code. Sec. 840&. p. 192. 1937 revision. California State Department of Agriculture, Sacramento, California. 8 Planta, A. von. Ueber die Zusammensetzung einiger Nektar-arten. Ztschr. Physiol. Chem. 10:227-47. 1886. Kenoyer, Leslie Alva. Environmental influences on nectar secretion. Iowa Agr. Exp. Sta. Eesearch Bul. 37:219-32. 1916. Caillas, Alin. Composition and changes in nectar. Amer. Bee Jour. 66(5) : 226-27. 1926. Beutler, Euth. Sitzungsber. Gesell. fur Morph. u. Physiol, in Munchen 39. 1929. (Original not seen; reported in the Bee World 11(4) :47-48. 1930.) Park, Wallace. The storing and ripening of honey. Amer. Bee Jour. 64(7) :330-32. 1924. Vansell, G. H. The sugar concentration of some western nectars. Bees and Honey 18(5) :150-51. 1937. 6 University of California — Experiment Station such environmental factors as temperature, moisture, light, soil, and atmospheric pressure. The total sugar content of nectar from various sources as given by Vansell is as follows : Total sugars, Total sugars, Floral source per cent Floral source per cent Pear, Bartlett 9.0 Plum, variety unknown 32.0 Pear, Bartlett 10.2 Loco weed, Astragalus Pear, Bartlett 10.6 Watsonii 33.3 Cherry, sour 15.5 Manzanita 37.5 Peach, variety unknown 15.5 Peach, variety unknown 43.5 Pear, Bartlett 16.9 Cherry, Black Republican 50.8 Peach, variety unknown 17.2 Cherry, Royal Anne 60.8 Cherry, mazzard 18.5 Oregon grape 63.4 Flowering currant 18.9 Maple, big-leaf 67.4 Prune, Italian 21.7 Willow 70.7 Plum, Shiro 22.8 Common mustard 71.2 Pear, Duchess 23.8 Maple, big-leaf 71.8 Madrone 24.2 Rape 72.6 Prune, French or Petite 26.9 Red filaree 77.0 Date-plum 30.5 Nectar also contains certain enzymes, such as invertase, as is evidenced by the amount of reducing sugars present. Callais gives the following analysis for orange-blossom nectar : Component Per cent Component Per cent Reducing sugars 17.640 Undetermined 0.628 Saccharose 8.217 Moisture 72.800 Dextrines 0.715 The manner in which bees reduce the high percentage of moisture con- tained in nectar and invert the sucrose to dextrose and levulose has been the subject of investigation by many observers. For years the process was thought to be purely one of evaporation, that the bees add invertase to the nectar, deposit it in their combs, and then evaporate the excess mois- ture by causing air currents to be circulated through the hive by fanning their wings. Thomson 9 saw bees throw off a fine spray while flying be- tween a point at which they were feeding on thin sirup and their hives, and concluded they were able to separate the excess water from nectar in their bodies while on wing. Various beekeepers of that same period, and before, had observed that field bees threw off a fine spray of a colorless liquid as they returned to their hives, which led to the rather general be- lief that bees could remove the excess moisture in nectar by physiological processes while flying. Doolittle 10 observed that the field bees on entering 9 Thomson, C. How the bees remove the water from thin honey. Gleanings in Bee Culture 8(6):270-71. 1880. 10 Doolittle, G. M. That new plan to prevent swarming. Gleanings in Bee Culture 22(6) :462-63. 1894. Bul. 631] Properties of California Honeys 7 the hive gave their loads of nectar to house bees under 16 days of age and these in turn deposited the nectar in the cells. Some years later Miller 11 observed that a bee whose honey stomach was filled with nectar would force out a small drop of liquid from her mouth and then withdraw it after a brief period, continuing the process for an undetermined length of time. He conjectured that this behavior was con- nected with the ripening or conversion of nectar into honey. Brunnieh 12 advanced another theory on the ripening of nectar that in- cluded the separation of a large part of the excess water from the nectar through the walls of the bee's honey stomach and thence to the exterior via the rectal glands and natural elimination while on wing. Park 13 agreed with Doolittle and Miller but elaborated on the manner in which the bees handled the nectar to evaporate a large part of the mois- ture and to invert the sucrose into dextrose and levulose before placing it in the cells. Park 14 showed by later experiments that nectar could be ripened to the consistency of honey in about 3 days if the combs were placed behind a screen in a super of a hive. He further showed that nectar is not concentrated between the field and the hive by physiological proc- esses within the bee. Numerous observations indicate that under normal conditions it takes about 3 days for the bees to convert nectar into ripe honey. METHODS OF DETERMINATION AND ANALYSIS Collection of Samples. — A collection of different samples of honeys pro- duced in California was started for this study in 1932. In collecting the samples, an attempt was made to secure unheated honeys that were thought by the producer to be true to a given plant source. In some in- stances, however, an unknown amount of heat, generally insufficient to affect the color or flavor materially, had been applied during the process of extraction and clarification. A noticeable variation from the average for the source in color, flavor, or other properties in any of the samples probably indicates the presence of honeys from other plant sources rather than the change due to the application of heat. Since it is difficult for a producer to keep honeys from various sources wholly separate, the samples collected were considered to be typical of the general run of honeys to be found in the retail and wholesale trades. 11 Miller, Arthur C. A mysterious act: peculiar habit of worker bees revealed by observation and its possible bearing upon current subjects of discussion. Amer. Beekeeper 14(1) :7-8. 1904. 12 Brunnieh, K. About the bees' honey. Amer. Bee Jour. 59(2) : 56-57. 1919. 13 Park, Wallace. The storing and ripening of honey. Amer. Bee Jour. 64(7): 330-32. 1924. u Park, Wallace. How bees remove water from nectar. Iowa State Apiarist Bept. December 31, 1927. p. 83-88. 1927. 8 University of California — Experiment Station All samples were heated to 145° Fahrenheit and strained before the different determinations were made. When samples were received in the granulated condition, they were heated at 145° until all granules were dissolved. The honeys were then kept in airtight containers of glass or tin until needed. As the samples were secured over a period of five years, they were not observed on a comparative basis for granulating pro- pensities. Determination of Color. — The United States standard honey color grader, also known as the "Pfund color grader," was used to determine the colors of the honeys studied. This instrument is provided with a graduated scale to indicate the color equivalent and grade divisions. Thus honeys may be classified, according to color, into seven grades, as follows : Water white, to 8 ; extra white, 9 to 16 ; white, 17 to 33; extra light amber, 34 to 48 ; light amber, 49 to 84 ; amber, 85 to 113 ; and dark, 114 to 140. The presence of green, red, or bright-yellow colors in some samples made close determination of the color grade difficult, because these colors are not compensated for in the amber-colored glass wedge of the color grader. Certain of the samples were rather turbid, even after they had been heated and strained. This turbidity is characteristic of some honeys and is not due entirely to small air bubbles held in suspen- sion. Turbidity tends to give honey a darker appearance and a lower rating on the color grader than is the case when the same honeys are properly clarified. All color readings were made as soon as the samples were available. Determinations of Weight and Moisture. — The weight per gallon and moisture content of each sample of honey were determined by the use of the Brix hydrometer and an Abbe refractometer according to methods and tables described by Marvin. 15 The moisture content was also deter- mined chemically, as described later. Since the refractometer is coming into more common use for determining not only the weight per gallon and the moisture content of honey but also the percentage of sugar as in- dicated by the total solids, these equivalents are included in the tables with the chemical analyses. Chemical Analyses. — The methods used in making the chemical anal- yses conformed throughout with the recommendations of the Association of Official Agricultural Chemists 16 with the exception of the acid deter- 15 Marvin, G. H. Methods of determining the weight per gallon of honey. Amer. Bee Jour. 73: (ll):426-28. 1933. Marvin, G. H. The weight per gallon of honeys from various floral sources. Jour. Econ. Ent. 27(3) :608-ll. June, 1934. 16 Skinner, W. W. Official and tentative methods of analysis of the Association of Official Agricultural Chemists. 4th ed. p. 487-89. Association of Official Agricul- tural Chemists, Washington, D. C. Bul. 631] Properties of California Honeys 9 minations, in which the acid was expressed in percentage of formic acid rather than in the number of cc of 0.17V NaOH per 100 grams of honey. This change was made in order to have the results comparable with those of other publications in which the acid content was expressed as formic. Furthermore, all polarization determinations were made with a 100-mm tube instead of a 200-mm tube. The majority of the samples were more than one year old before it was possible to analyze them chemically. Tabulation of Data. — In tables 1 and 2, the various honey samples are arranged alphabetically as to the floral sources indicated by the pro- ducers. The accuracy of such designations could not be positively checked by microscopical examinations of the included pollen grains. Where the chemical and physical determinations of a sample are at a considerable variance from the average for the same source, natural blending of nec- tar from more than one source during the extracting process should be suspected. Owing to unavoidable circumstances, the analyses could not be completed for honey samples nos. 39, 60, 87, 95, and 126. SOME PHYSICAL CHARACTERISTICS OF HONEYS Color. — The color grades of the different honeys as indicated by the scale on the Pfund grader ranged from 2 for a sample of black-sage honey to 131 for a sample of honey from eucalyptus. The scale of the Pfund grader is so constructed that a slight change in hue among the paler honeys often results in a different grade determination. A comparison of the grade points, therefore, is more indicative of the color variance than the color designation for each grade. Color in honey depends on a combination of several factors. Tables 1 and 2 (p. 16) indicate considerable variation, in many cases, in the grade color of samples from the same floral source. One must take into account some of the causes of color in honey in order to explain or to understand these differences. Lothrop and Holmes 17 found that the color of honey increased with an increase in the colloidal constituents and that the clarity of honey was likewise affected. Most honeys contain small quantities of plant pigments, the value of which cannot be indicated accurately by the Pfund grader. Star-thistle honey, for example, has a very characteristic greenish cast not found in other California honeys. Alfalfa honey produced in valley districts of the state is uniformly darker in color than alfalfa honey produced at the higher elevations. The density of honey has little to do with color variations, but in retail pack- 17 Lothrop, R. E., and R. L. Holmes. Determination of dextrose and levulose in honey by use of iodine-oxidation method. 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N CD N N N N o o "5 O 16.96 16.78 16.28 14.80 16.72 16.33 15.65 15.28 16.55 15.90 >o 00 »ca oo CO >*5 "5 oo t^ oo ■«*< 16.23 19.80 19.25 IO o ■** o lO OO OS rH OO CO N Oti 00 t^- o oo io i« o W N 00 N CO iQ CO O CN ■* o o oo o . 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OS £j ^ J3 J^ 3 ^H ^H s (O CJ CM o ■ t-- CC iH CI ■ CO (M CN CO 00 00 • OO co co •^ IO • CO a CO ■*f eo »o ■ f >c eo "* ' H *■■ • -i-H eo o • OO ^H OS OS OS • OS o- «»» ■^ • -ct" - 1 -< -' -■ • ~* ^ £ >s a s -i nd fl r^ IS T3 CP H ^ oj c* c '3 3 O £ -a 5 x> If co J5 CI Gv c rt to c If fl |S o a M a © CO co a- c3 CN c 1 c o S c 2 c3 o 03 £ is t-i c J' S C *3 X' c O C 5? ^ c9 1 03 1 as ea ^ c X -Q -^ co a a | ^ OS CO rt< 00 O «5 •* M5 CO (M (M (M . © i-H © CO CO © M N (O W © 00 CO OO t^ IO «-H t^ CO CO -«f »o ■* »o >o * OO to n n in "fl 00 O CO IO » M N « O + + + + + © © CO 1-H t^ IO + + + + I CM -H >-l co >0 eo eo CO CO »o OO OO 00 CO 00 OO CO OO 0O O N N ^H T* OS ■* "* CO 'CM ^3 t~- ■* CO CO t-i i-H CM ,3 C ^ ^ o o 6 3 55 ^ fc ^ ^^ A !? 03 CO C O OP 5 2 > >fl < 16 University of California — Experiment Station table 2 Some Physical Properties of Special Samples of California Honeys Floral sources Sample no. Refrac- tive index Total* solids Mois- ture* content Weight* per gallon I 35 Color 1? •g-o « 53 Ch 5 Fair at which samples were collected per cent per cent lbs. mm Alfalfa 128 1.4930 81.25 17.4 11.83 34 Ex. light amber 4 State 129 1.4900 80.10 18.4 11.77 28 White 1 Los Angeles 130 1.4905 80.25 18.4 11.78 30 White 2 Los Angeles 131 1.4985 83.35 15.2 11.95 28 White 3 Los Angeles 132 1.4910 80.50 18.2 11.78 46 Ex. light amber 4 Los Angeles Av. 1.4926 81.09 17.5 11.82 33 Buck- 133 1.4980 83.15 15.4 11.94 47 Ex. light amber 2 Los Angeles wheat 133-A 1.4955 82.20 16.3 11.89 45 Ex. light amber Los Angeles 134 1.4985 83.35 15.2 11.95 58 Light amber 3 Los Angeles 135 1.4990 83.75 14.9 11.96 47 Ex. light amber 1 State 135-A 1.4970 82.70 15.8 11.92 49 Light amber State 136 1.4982 83.15 15.3 11.95 48 Ex. light amber 2 State 136-A 1.4867 79.50 19.0 11.74 43 Ex. light amber State Av. 1.4961 82.54 16.0 11.90 48 Blackeye 137 1.4980 83.15 15.4 11.94 55 Light amber 1 San Mateo bean Lima 138 1.4932 81.25 17.3 11.84 24 White 1 Los Angeles bean 139 1.4910 80.50 18.2 11.78 22 White 2 Los Angeles 140 1.4900 80.00 18.4 11.77 23 White 3 Los Angeles 141 1.4905 80.25 18.4 11.78 25 White 4 Los Angeles 142 1.4951 82.00 16.5 11.87 11 Extra white 1 State 143 1.4950 82.00 16.5 11.87 14 Extra white 2 State Av. 1.4929 81.00 17.6 11.82 20 Cotton 144 1.4965 82.50 16.0 11.90 34 Ex. light amber 1 Los Angeles 145 1.4961 82.40 16.1 11.90 27 White 1 Los Angeles 146 1.4947 81.80 16.7 11.86 34 Ex. light amber 2 Los Angeles 146-A 1.4986 83.40 15.2 11.95 29 White Los Angeles 147 1.4965 82.50 16.0 11.90 28 White 3 Los Angeles Av. 1.4965 82.52 16.0 11.90 30 Orange 148 1.4978 83.00 15.5 11.93 10 Extra white 1 State 149 1.4965 82.50 16.0 11.90 9 Extra white 1 Los Angeles 150 1.4946 81.80 16.7 11.86 9 Extra white 2 Los Angeles 151 1.4931 81.35 17.4 11.83 13 Extra white 3 Los Angeles 152 1.4940 81.50 16.9 11.85 37 Ex. light amber 4 Los Angeles Av. 1.4952 82.03 16.5 11.87 16 Sage 153 1.4960 82.35 16.2 11.89 8 Extra white 1 Los Angeles 154 1.4960 82.35 16.2 11.89 12 Extra white 2 Los Angeles 155 1.4940 81.50 16.9 11.85 10 Extra white 1 State 156 1.4965 82.50 16.0 11.90 13 Extra white 2 State Av. 1.4956 82.18 16.3 11.88 11 Yellow 157 1.4950 82.00 16.5 11.87 29 White 1 State star 158 1.4993 83.65 14.8 11.97 26 White 2 State thistle 159 1.4900 80.15 18.5 11.77 33 Ex. light amber Av. 1.4948 81.93 16.6 11.87 29 Grand average 36 1.4948 81.93 16.6 11.87 29 As determined by refractive index equivalents. Bttl. 631] Properties of California Honeys 17 ages the depth of honey through which light rays have to pass adds con- siderably to the amount and value of the light rays absorbed, so honey in a thin glass container will appear lighter than the same honey in a con- tainer of larger diameter. As indicated in table 3, honey darkens slowly with age. Heat likewise causes a rapid change in its color if too much heat is applied. Paine and Lothrop 18 found this to be due in large measure to the presence of amino acids, which combine with the sugars to produce dark-colored com- pounds. Honeys that contained relatively large quantities of colloidal constituents darkened to a greater extent than honeys which contained smaller quantities of colloids. The removal of the colloids by ultrafiltra- tion methods reduced the tendency of such honeys to discolor or to car- amelize when heated to the higher temperatures used in cooking. Lynn, Englis, and Milum, 19 on the other hand, found that darkening of honey is due primarily to instability of the fructose of honey. Under commercial conditions of production, honey is often heated to 130° Fahrenheit to facilitate straining, and to between 145° and 160° for bottling. Honey will increase in color at these temperatures when allowed to cool slowly over an interval of several hours but little change will occur when the heat is applied quickly and cooling takes place rapidly : when honey that graded 30 on the Pfund grader was heated to 160° and poured into two 60-pound honey cans in a wooden shipping case, a temperature of 100° was recorded 24 hours later and a darkening of 10 grade points had taken place ; but a series of California honeys of different sources and colors did not change appreciably in color when heated to 160° for 2 hours and then cooled within a few minutes. Weight per Gallon. — The weight per gallon of honey is influenced by the moisture content, which, in turn, is affected by the floral origin, tem- perature, and humidity, as well as by methods used by the beekeeper in his manipulation of the combs during production. Honey that is ex- tracted from the comb before the excess moisture has been completely evaporated by the bees is higher in moisture content and, therefore, weighs less per gallon than honey that has been thoroughly ripened by the bees before the combs are taken from the hive. This factor may easily nullify the effects of natural factors, so that only general deductions can be made in regard to the weights per gallon of the different honeys analyzed. 18 Paine, H. S., and B. E. Lothrop. Influence of colloidal constituents on the devel- opment of color in honey. Amer. Bee Jour. 73(1) :23, 27. 1933. Paine, H. S., and E. E. Lothrop. Small plant for filtering honey. Gleanings in Bee Culture 63(7) :395. 1935. 19 Lynn, E. G., D. T. Englis, and V. G. Milum. Effect of processing and storage on composition and color of honey. Food Eesearch 1(3):255-61. 1936. 18 University of California — Experiment Station TABLE 3 Some Physical Properties of Honeys of Various Ages (Determinations made in 1938) Floral source and sample no. Alfalfa: No. 160 No. 161 No. 162 No. 163 No. 164 No. 165 No. 166 Agastache, no. 167 Cascara, no. 181 Cherry blossom, no. 168 Bean, lima: No. 169 No. 170 No. 171 Cotton, no. 172 Carrot and asparagus, no. 173 Holly.no. 174 Honeydew and incense cedar, no. 175 Buckeye and honeydew, no. 176. . Buckeye, no. 177 Buckeye and wild alfalfa, no. 178. Mesquite, no. 179 Plum and mustard, no. 180 Orange: No. 182 No. 183 No. 184 Sage and orange: No. 185 No. 186 Creeping sage, no. 187 White and black sage, no. 188 Sage: No. 189 No. 190 No. 191 Star thistle and alfalfa, no. 192. . . Star thistle: No. 193 No. 194 No. 195 No. 196 No. 197 No. 198 Star thistle and alfalfa: No. 199 No. 200 No. 201 Star thistle and jagger weed , no. 202 Age years 7 7 7 15 14 14 14 7 Refrac- tive index 1.4973 1.4969 1.4962 1.4977 1.5011 1.4877 1.4992 1.4921 1.4930 1.4914 1.4973 1.4979 1.4965 1.5033 1.4964 1.4970 1.5077 1.4875 1.4951 1.4945 1.5009 1.4925 1.5015 1.4937 1.4940 1.4961 1.4981 1.4936 1.4915 1.5030 1.4962 1.4958 1.4852 1.4943 1.5015 1.5010 1.4940 1.4966 1.4990 1.5077 1.5001 1.4910 1.5027 Mois- ture per cent 15.7 15.8 16.1 19.5 14.1 19.5 14.9 17.7 17.4 18.0 15.7 15.4 16.0 13.3 16.0 15.8 11.8 19.6 16.5 16.7 14.0 17.6 14.0 17.0 16.9 16.1 15.4 17.2 18.0 13.4 16.1 16.2 20.6 16.8 14.0 14.1 16.9 15.9 14.9 13.5 14.1 18.1 13.5 Solids per cent 82.6 82.5 83.0 84.3 79.2 83.6 80.8 81.2 80.5 82.8 83.0 82.5 85.2 82.5 86.7 79.0 82.0 81.7 84.3 81.0 82.4 83.2 81.4 85.0 82.4 82.3 78.2 81.6 84.4 84.2 81.5 82.5 83.5 84.9 84.2 80.5 Weight per gallon pounds 11.92 11.91 11.90 11.72 12.00 11.72 11.96 11.81 11.83 11.80 11.92 11.94 11.90 12.05 11.91 11.92 12.10 11.71 11.88 11.86 12.00 11.82 12.01 11.85 11.85 11.90 11.94 11.84 11.80 12.05 11.90 11.89 11.67 11.86 12.01 12.00 11.85 11.91 11.96 12.04 12.00 11.79 12.04 Pfund grade mm 75 125 126 140+ 137 140+ 127 111 140+ 140+ 140+ 106 118 126 140+ 129 140+ 140+ 140+ 140+ 114 140+ 123 105 107 118 121 85 91 111 67 140+ 140+ 105 119 139 140+ 131 140+ 140+ 140+ 140+ Average color, fresh sample Ex. It. amber Ex. It. amber Ex. It. amber Ex. It. amber Ex. It. amber Ex. It. amber Ex. It. amber Ex. It. amber Amber Amber White White White White Lt. amber Lt. amber Amber Amber Lt. amber Lt. amber Lt. amber Amber White White . White White White White White White White White Ex. lt. amber White White White White White White Ex. It. amber Ex. lt. amber Ex. lt. amber Lt. amber Bul. 631] Properties of California Honeys TABLE 3— (Continued) 19 Floral source and sample no. Age Refrac- tive index Mois- ture Solids Weight per gallon Pfund grade years per cent per cent pounds mm 8 1.4930 17.4 81.2 11.83 140+ 8 1.4907 18.3 80.4 11.78 140+ 13 1.4920 17.8 80.7 11.81 140+ 14 1.4966 15.9 82.6 11.91 122 14 1.4930 17.4 81.2 11.83 140+ 14 1.4925 17.6 81.4 11.82 140+ 14 1.4975 15.6 82.9 11.93 140+ 15 1.4975 15.6 82.9 11.93 140+ 7 1.5027 13.5 84.8 12.04 139 7 1.4970 15.8 82.7 11.92 126 7 1.4982 15.3 83.2 11.94 123 13 1.4950 16.5 82.0 11.87 140+ 8 1.4946 16.7 81.7 11.87 139 Average color, fresh Spikeweed: No. 203 No. 204 Blend: No. 205 No. 206 No. 207 No. 208 No. 209 No. 210 Honeydew, incense cedar, no. 211 Orange, no. 212 Wild clover, no. 213 Yellow star thistle, no. 214 Alfalfa, no. 215 Lt. amber Lt. amber Lt. amber Lt. amber Lt. amber Lt. amber Lt. amber Lt. amber Amber White Ex. lt. amber White Ex. lt. amber Only two samples — mountain misery no. 4 and tarweed no. 46 — fell below the minimum weight per gallon, 11.75 pounds, set by the Cali- fornia Code. The average weight for all of the samples was 11.88 pounds per gallon, as determined by the use of the Abbe ref ractometer and Mar- vin's tables. Granulation. — The granulation of honey is a natural physical char- acteristic influenced by a number of natural and artificial factors. Honey is, essentially, a supersaturated solution of three sugars, levulose, dex- trose, and sucrose, so that crystallization may be expected to be the gen- eral rule rather than the exception. Phillips 20 pointed out that in the granulation of honey only the dextrose crystallizes and the levulose and sucrose remain in solution as a liquid film around the dextrose crystals. Since the dextrose hydrate crystal contains one less molecule of water than dextrose in solution, the percentage of moisture in the liquid phase of granulated honey is greater than when all of the sugars are in solu- tion. An increase of the levulose content, expressed as the levulose : dex- trose ( jr ) ratio, tends to retard granulation. This character is noticed particularly in the sage honeys of California, which are noted for their nongranulating qualities. Honeys produced from the nectars of blue curls, rosin weed, and tarweed, have the ■=> ratios of 0.88 to 0.91, 1.03, and 1.17, respectively, and are known to granulate very rapidly. In this 20 Phillips, E. F. Some physical peculiarities of honey. Gleanings in Bee Culture 57(9):570-72. 1929. 20 University of California — Experiment Station investigation, granulation took place earlier in those samples of honey whose levulose : dextrose ratio was lower than the average for the same source, which demonstrates a variation in this factor within even a given source. Furthermore, honeys in the extracted form granulate faster than when left sealed in the comb, which indicates that the inclusion of air bubbles during the extracting process hastens granulation. Another characteristic of the crystallization of honeys is that the speed of granulation has a direct bearing on the size of the crystals formed. Those honeys which granulate quickly form smaller crystals and hence have finer texture than those which granulate slowly. Crystalliza- tion is generally uniform in the fast-granulating honeys, but irregular in many honeys that granulate slowly. Stirring tends to hasten granulation and to reduce the size of the granules formed. Crystallization may be in- duced by adding small crystals of a finely granulated honey to liquid honey and distributing them uniformly throughout by stirring. The presence of dust particles in the containers or the inclusion of air bubbles during the extracting process also increases the tendency of a honey to granulate. Dyce 21 found that a temperature of 57° F was the most favor- able for speedy granulation of the average-density honey, with the heavy honeys requiring 1° or 2° above this average. Several of the samples of honey described in table 3 granulated solidly in the lower portion but were liquid on top. Sample 39 in table 1 granu- lated similarly, the liquid portion being much thinner than the whole sample after the granulated portion had been liquefied by heating. Par- tial granulation of a sample of honey can be induced by blending honeys of different specific gravities without the application of sufficient heat and by not stirring sufficiently to cause a uniform solution throughout. The same phenomenon occurs when honeys of different specific gravities are extracted and placed in the same tank : the lighter honeys will rise to the top, and the heavier portions below tend to granulate first. The application of heat to granulated honey dissolves the crystals and tends to retard granulation. The length of time and degree to which a honey has to be heated to prevent granulation or to reliquefy it when it has granulated, varies somewhat with its type or floral source. Most of the honeys that granulated could be liquefied with the application of 145° F for a period of from 1 to 4 hours ; but other honeys, and particu- larly mesquite honey, had to be heated to a higher temperature and for a longer period. The older honeys listed in table 3 had to be heated for a longer period than did the more recently produced samples from the same floral sources. 21 Dyce, E. J. Crystallization of honey. Jour. Econ. Ent. 24(3) :597-602. 1931. Bul. 631] Properties of California Honeys 21 A high sugar concentration retards fermentation in honey. Granulated honey is more prone to ferment than the same honey in the liquid condi- tion because of the higher moisture content in the liquid phase surround- ing the dextrose crystals. Since honey is hygroscopic, the probability of fermentation can be reduced by storing honey in air-tight containers in a dry atmosphere. Wilson and Marvin 22 found that temperatures below 52° F not only retarded the growth of the sugar-tolerant yeasts which cause fermentation but also prevented change in color of the honey samples. Flavor. — One of the most important components of honeys is flavor, a character that is impossible to measure or describe adequately because of the variation in the preferences of different individuals. As a rule, the characteristic flavor of a honey is definite and typical of the source from which it is produced, although the aroma is not neces- sarily the same as that of the flower. Sometimes the flavor closely re- sembles the aroma of the flower from which the nectar is gathered, but not all flowers yielding nectar are aromatic, and not all aromatic blossoms produce nectar. The exact nature of the substances causing flavor in honey is not fully understood. Nelson 23 obtained by distillation a small residue from orange honey that had the odor and certain chemical properties of methyl an- thranilate. Not all of the honeys listed in table 1 could be described as pleasant or agreeable to the taste, and on this basis most honeys can be divided into two classes — table honeys and baking varieties. This distinction is not entirely suitable, however, because all of the more delicately flavored table honeys may be used in cooking ; the flavors can be imparted to food products that do not require too high a temperature in their preparation. Since the stronger flavors of honeys are generally reduced or driven off at the higher temperatures without reducing the other admirable quali- ties of honey in connection with baked goods, the more flavorful honeys can be used for such purposes. Honeys derived from the California buck- eye, prune blossoms, rabbit brush, rosin weed, tarweed, and others of similar strong flavor should not be sold in the general retail market as table varieties. The flavors of honeys are more pronounced when the honey is finely granulated than when liquid or coarsely granulated. Many who sample a smoothly crystallized honey for the first time are very agreeably sur- 22 Wilson, H. F., and C. E. Marvin. The effect of temperature on the keeping qualities of honey. Jour. Econ. Ent. 24(3) :589-97. 1931. 23 Nelson, E. K. The flavor of orange honey. Indus, and Engin. Chem. 22(4) :448. 1930. 22 University of California — Experiment Station prised at the greater flavor. There is a greater demand for honeys that have a creamy consistency on granulating than for honeys that produce coarse crystals. The older honeys listed in table 3 had lost much of the characteristic flavor and practically all of the typical aroma of more recent samples of the same floral sources. ANALYTICAL DATA Moisture. — The percentage of moisture in the honey samples listed in table 1 averaged 16.50 when determined chemically and 16.39 when de- termined by the Abbe refractometer, a difference of but 0.11 per cent : for practical purposes, the refractometric method of determining this factor in honey is evidently both accurate and feasible. The moisture content (by analysis) ranged from 19.80 per cent in a sample of tarweed honey, no. 46, to 13.95 per cent for a combination of sweet clover and alfalfa honey, no. 122 (table 1). As stated previously, the percentage of moisture in honeys from the same floral sources may vary considerably because of manipulative practices during production. All samples were under the maximum limits for moisture set by the regu- lations of the Agricultural Code of California and over 5 per cent lower than the federal maximum. Total Sugars. — The average total sugar content in the samples ana- lyzed was 77.53 per cent, invert sugars constituting 74.95 per cent and sucrose 2.53 per cent. The invert sugars were made up of 40.41 per cent of levulose and 34.54 per cent of dextrose, or a levulose : dextrose ratio of 1.17. The honeys with the highest average content of levulose were the sages, with 42.85 per cent ; sage honeys also had the highest levulose : dextrose ratio. It is this feature that makes these honeys practically nongranu- lating. 24 The honeys with the highest average content of invert sugar were : the alfalfas with 77.51, the clovers with 77.10, the lima beans with 75.95, the California buckwheats with 75.54, the spikeweeds with 75.38, and the eucalyptuses with 74.92 per cent; several single honey samples had comparable percentages. The total sugar content, as determined chemically, was 4.57 per cent lower on the average than the total solids indicated by the refractometer. While a major portion of the total solids in honey is composed of the sugars, this discrepancy of 4.57 per cent should be taken into considera- 24 There is a sample of sage honey in the honey collection at the University of California, at Davis, produced by the late M. H. Mendleson in 1886. The sample is now wine-red in color and has coarse crystals to the depth of an inch in the rather narrow glass container. Bui* 631] Properties of California Honeys 23 tion when the refractometer is used to indicate the percentage of sugars present. The average percentage of sucrose present in the samples, 2.53, was well within both the state and federal regulations. In only one sample, orange blossom no. 55, did the percentage of sucrose exceed the regula- tions. In this sample, the 11.0 per cent of sucrose was unusual, for the moisture content of 17.03 per cent would indicate that the honey was TABLE 4 Compilations of Tabular Data Based on Color of Samples Color of sample Num- ber of sam- ples Refrac- tive index Weight per gallon Mois- ture Invert sugars Suc- rose Total sugars Dex- trin Ash Acid L/D Water white. 5 7 24 15 37 7 3 1.4963 1.4960 1.4963 1.4973 1.4943 1.4949 1.4920 lbs. 11.90 11.91 11.90 11.92 11.85 11.87 11.81 pet. 16.20 16.36 15.99 15.71 16.86 16.84 17.82 pet. 74.55 76.00 75.68 75.90 75.20 73.72 74.42 pet. 2.62 3.08 2.92 3.03 1.95 1.41 1.78 pet. 77.17 79.08 78.60 78.93 77.15 75.13 76.20 pet. 0.44 0.09 0.48 0.56 0.91 1.79 0.81 pet. 0.08 .10 .13 .17 .18 .31 0.49 pet. 0.09 .10 .15 .16 .17 .22 0.22 1.35 Extra white 1.16 White 1.15 Extra light amber Light amber 1.14 1.16 Amber 1.21 Dark 1.18 not "green," although some of the moisture may have been removed by evaporation after the honey had been extracted. Ash. — The ash content in the 106 samples averaged 0.21 per cent and ranged from 0.02 per cent to 1.14 per cent. Of the total number of sam- ples examined, 22.6 per cent were above the legal limit set by state and federal standards. In data published by Lothrop, 25 38.7 per cent of the samples reported had an ash content above the legal limit of the Pure Food and Drug Act. Since the ash content in pure honeys is so variable, it would seem desirable to set up a definite tolerance for this factor in order to prevent unwarranted discrimination against those above the average range. A summary of the tabular data based solely on color, as in table 4, indi- cates that the percentage of ash increased directly with the color. As the ash of honeys is composed of the mineral elements, the darker-colored honeys have a higher mineral content than honeys of lighter-colored varieties. This is in agreement with the determinations of Lothrop, 28 who also found that the minerals in honeys are decidedly alkaline in reaction. Since the acids of foods are largely burned up in the body during diges- 25 Lothrop, E. E. Adulteration of honey. Gleanings in Bee Culture 64(7):397-9. 1936. 20 Lothrop, R. E. The mineral constituents of honey. Araer. Bee Jour. 76(7) : 346-47. 24 University of California — Experiment Station tion and metabolism, the acid-alkaline balance of the body is dependent almost entirely on the mineral elements present. Hence, honey can be considered potentially alkaline as a food. Dextrin. — The dextrin content of the honey samples averaged 0.91 per cent but varied widely within honeys from the same floral source. The percentage of dextrin in the samples ranged from 11.91 per cent for flea- bane honey, sample no. 76, to 0.02 per cent for lima bean honey no. 63 and a similar quantity for orange-blossom honey no. 14 (table 1) . Table 4 indicates a general increase in the dextrin content with an in- crease in color except for the extra white and the dark samples, which were unusually low. Dextrin is evidently transmitted to honey through the nectar or may be an inclusion from other substances : Phillips 27 has shown that bees can- not utilize dextrin as a food and cannot change its chemical composition. Acid. — The acid in the honey samples averaged 0.16 per cent and ranged from 0.45 per cent to 0.07 per cent. Table 4 indicates a tendency for the acid content to increase directly with the color of honey. While the acidity of honeys is generally expressed as formic acid, the acid present in greatest quantity is probably malic acid and not actually formic acid at all. Enzymes. — During the ripening process, the cane sugar in nectar is largely inverted by the honeybee through the action of the enzyme in- vertase into levulose and dextrose. Nectar itself contains invertase, but additional amounts of this enzyme are produced by glands in the honey- bee. Other enzymes, such as diastase, catalase, and inulase have also been found in honeys in small quantities. Vansell and Freeborn 28 found that diastase in honey was derived from included pollens and therefore was not a true component of honey itself. Undetermined Materials. — The undetermined materials averaged 4.72 per cent and ranged from 2.30 per cent to 7.15 per cent. This amount was slightly higher than the 3.73 per cent reported by Browne. 20 These un- determined compounds were probably composed of wax particles and pollen grains, as well as volatile acids, aromatic bodies, albuminoids, and other substances of unknown character. In general, the undetermined percentages were higher in those honeys which had a high dextrin content. 27 Phillips, E. F. The utilization of carbohydrates by honeybees. Jour. Agr. Re- search 35(5):385-428. 1927. 28 Vansell, G. H., and S. B. Freeborn. Source of honey diastase. Gleanings in Bee Culture 57(8) :518. 1929. 2(> Browne, C. A. Chemical analysis and composition of American honeys. U. S. Dept. Agr. Bur. Chem. Bui. 110:1-93. 1907. Bul. 631] Properties of California Honeys 25 HONEYDEW HONEYS The term "honeydew" is often applied to the saccharine exudations of extrafloral nectaries and other plant pores as well as the sweet excretions produced by certain insects feeding on plant growth. The bees gather these exudations at times when floral nectar is not available and convert them into a food product just as with floral nectar. Honey made from Fig. 1. — Quercus lohata, the valley oak, produces honey- dew at certain seasons of the year. The arrow indicates the point at which the honeybee collects the excretion. The galls on the leaves do not produce honeydew. extrafloral nectaries cannot be distinguished from honeys made solely from nectar of floral origin, but there is a striking difference between these honeys and the products made from the sweet excretions of certain insects. Consequently, the term "honeydew honey" should be applied only to the latter and not to such honeys as are made solely from nectar of plant origin. In California many tons of honeydew honey are produced on a com- mercial basis from the sweet excretions of certain insects belonging to the Coccidae (scale insects), Aphidae (plant lice), Jassidae (leafhop- pers), Membracidae (tree hoppers), and Cynipidae (gall insects). The formation of this sweet excretion is little understood, but it is produced in large quantities from various pines, cedars, firs, oaks, willows, etc. The 26 University of California — Experiment Station largest quantities are produced from the incense cedar (Libocedrus decurrens) and the valley oak (Quercus lobata) (fig. 1). Honey dew honey is especially plentiful in dry seasons, which are favorable to the insect development. The product is generally dark in color and undesira- ble in flavor, although some beekeepers report crops of honeydew which are light in color and of excellent flavor. The six samples of honeydew honey analyzed (table 1, p. 10) differed considerably from the honey samples in both composition and physical properties. They were dextrorotatory, low in invert sugars, and high in dextrins and ash. They were extremely viscous, a character that readily distinguishes them from the floral varieties of honey. Despite their dark color, honeydew honeys have been found to have many highly desirable qualities when used in the bakery trade. SUMMARY Our studies have shown that honeybees in California produce a variety of honeys that differ in physical and chemical properties with the floral sources from which they are produced. Thirty-seven of these different types have been described and analyzed chemically, together with other samples of mixed origin. Specific samples are at times difficult to obtain because of the blending of honeys from different sources by the honeybee in the comb or during the extracting process. Analysis of all samples indicated that the average California honey consisted of the following components, in percentages of the total : mois- ture, 16.50, total sugars, 77.53 ; levulose, 40.41 ; dextrose, 34.54 ; sucrose, 2.53 ; dextrin, 0.91 ; ash, 0.21 ; acid, 0.16 ; and undetermined, 4.72. The levulose : dextrose ratio was 1.17, the weight per gallon 11.88 pounds, and color 49, or extra light amber. The use of the ref ractometer to determine the moisture and sugar con- tent of honey as well as the weight per gallon, was found to be close enough to the chemical determinations to warrant this less expensive method in making determinations of these factors. Various samples of honey have been shown to darken with time and temperature. Obviously, honey should not be heated to a temperature or for a length of time that will injure its color or flavor, and less change in the color of honey is to be expected if honey is stored at a cool tempera- ture than at higher temperatures. The samples of honey conformed to all standards of quality set by the state and federal regulations with the exception of the ash content. The fact that 22.6 per cent of the samples here reported are above the legal maximum ash content would indicate that a greater tolerance in the Bul. 631] Properties of California Honeys 27 official limits should be made in order to prevent discrimination against certain commercial honeys. The honeydew honeys examined were shown to differ considerably in chemical and physical properties from the samples from floral sources and consequently should not be confused with the floral honeys. While honeydew honeys cannot be considered in the class with table honeys, they should be quite acceptable to the bakery trade. ACKNOWLEDGMENTS The writers wish to express their appreciation to the many beekeepers who cooperated in this study by supplying the necessary honey samples ; and to Dr. C. S. Bisson for his critical interest and many suggestions throughout the entire period of this investigation. 14m-9,'39(9345)