UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 CIRCULAR No. 279 
 October, 1924 
 
 THE PREPARATION AND REFINING OF 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 By W. V. CRUESS 
 
 INTRODUCTION 
 
 Olive oil has been used by southern European peoples as an 
 important food since the beginning of historical time. Large areas 
 in Spain, Italy, France, Greece, and other Mediterranean countries are 
 planted with olives, while the preparation and refining of olive oil are 
 basic industries in these countries. 
 
 This publication has been prepared as a report upon observations 
 made during a recent visit to tfie olive oil producing and refining 
 centers of Spain, France, and Italy. 
 
 The attainment of the objects of this visit was greatly facilitated 
 by information and assistance generously furnished by various indi- 
 viduals and firms. In Spain by W. C. Burdette, American Consul, 
 and Francisco Martin, American Vice-consul at Seville ; Ernesto Peter 
 of Seville; the Union Oliverera of Carmona; R. Sala of Balaguer; 
 Dr. August Matons, University of Barcelona; Don Isidoro Aguilo, 
 Director of the Olive Experiment Station of Tortosa; R. J. Totten, 
 American Consul General, Barcelona. In France by L. Frost, Amer- 
 ican Consul General, Marseilles ; Victor Coq et Fils, machinery manu- 
 facturers of Aix-en-Provence. In Italy by Professor Asher Hobson, 
 Dr. Trinchieri, and others of the International Institute of Agricul- 
 ture, Rome ; Commendatore Casardi, Florence ; and by F. Bertolli of 
 Lucca and New York. 
 
 The California Ripe Olive Association defrayed part of the expense 
 of the trip, for which due acknowledgment is made. 
 
 It is believed that the information collected and presented here 
 will be of interest to the olive oil manufacturers of California, and 
 of value in improving the quality of California oil. 
 
UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 GENERAL STATUS OF THE OLIVE OIL INDUSTRY IN EUROPE 
 
 Although olive oil is a staple food product in southern Europe, its 
 producers are not at present in a very prosperous condition. 
 
 1. Production. — According to Dore* the acreages of olives for the 
 various Mediterranean countries were in 1911 and 1922 as shown in 
 table 1. It is believed that Dore's figures are more accurate than those 
 published by other agencies because his data were secured through the 
 International Institute of Agriculture, which has unusually good 
 facilities for gathering such statistics. 
 
 TABLE 1 
 
 Acreage of Olives in Mediterranean Countries 
 (After Dore) 
 
 Country 
 
 France 
 
 Greece 
 
 Italy 
 
 Portugal 
 
 Spain 
 
 Algeria 
 
 Tunis 
 
 Area in olives, 1911 
 (in acres) 
 
 Area in olives, 1922 
 
 No data 
 252,566 
 5,700,000 
 No data 
 3,567,327 
 No data 
 No data 
 
 296,500 
 
 No data 
 5,659,000 
 
 815,500 (in 1920) 
 4,102,185 
 85,623 
 575,888 
 
 The production of oil varies greatly from year to year as shown 
 by the data in table 2, taken from Dore's report. See table 2, page 3. 
 
 The total production for 1921 was 550,466 long tons or 161,186,500 
 gallons; or 52,680,100 gallons (about 25 per cent) less than in 1922. 
 In most of the above countries a year of heavy production is followed 
 by one of light production ; e.g., the production in long tons for Italy 
 for the years 1918, 1919, 1920, 1921, and 1922 respectively were 
 256,000, 101,100, 180,600, 143,100, and 236,200. Nevertheless the 
 total production for the whole Mediterranean region is fairly constant. 
 
 The production per acre in Italy is lower than in France and 
 Spain because mixed plantings and intercropping are more common 
 in Italy. See also page 9. 
 
 2. General Economic Conditions of the Industry. — The manufac- 
 turers of olive oil in the countries visited complained that the cost 
 of production of oil has increased in recent years out of proportion 
 to the selling price — and that consequently the net returns are small. 
 
 * Dore, Valentino. Oleaginous Products and Vegetable Oils, Production and 
 Trade. Published by the International Institute of Agriculture, Villa Borghesi, 
 Borne, 1923. 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 3 
 
 (a) Spain. — While Spain produces more olive oil than any country 
 in the world, her oils are not so well known in other countries as those 
 of Italy and France. However, it is a recognized fact that much of 
 the Italian and French oil, particularly that for export, consists of 
 blends containing a large proportion of fine Spanish oil. 
 
 TABLE 2 
 
 Production of Olive Oil in Mediterranean Countries 
 
 (After Dore) 
 
 * France — after J. Bonnet La Culture de l'Olivier. 
 
 The probable cause for this situation has been the more rapid 
 progress made in Italy and France in the refining, blending, packag- 
 ing, and foreign marketing of oil. The refiners of Marseilles, Genoa, 
 the Lucca district, etc., have in the past offered attractive prices for 
 the finer grades of Spanish oil, leaving for the Spanish export markets 
 principally inferior grades. Thus, the Spanish labels have come more 
 or less into disrepute and the French and Italian oils have become 
 firmly established in the North and South American markets and 
 elseAvhere. 
 
 In recent years, Spain has made great progress in oil making and 
 refining. She now possesses modern mills and up-to-date refineries. 
 (See figure 1.) As a result, the average quality of her oils has been 
 greatly improved and her fine oils rank with the best of Italy and 
 France. The difficulty has been to convince consumers and dealers 
 of this fact. Consequently large quantities of Spanish oil are still 
 exported to Marseilles, Genoa, and other foreign refining centers for 
 blending purposes. 
 
4 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 The Spanish refiners and oil manufacturers are not well organized ; 
 there has therefore been very little cooperative effort in attempting 
 to develop foreign markets. 
 
 It must be remembered that the Spanish currency has not depre- 
 ciated nearly so much as the French and Italian. At the time of the 
 writer's visit, the Spanish peseta was equivalent to 14c American, the 
 French franc to 4%c and the Italian lira to 4 1 4c. At par, each of these 
 is equivalent to about 20c American. This disparity in value has 
 given the French and Italian dealers a great price advantage over the 
 
 Fig. 1. — Upper, new building of Union Oliverera oil factory, Carmona, 
 Spain. Lower, oil refinery, Italy. 
 
 Spanish dealers, because production costs have not increased in France 
 and Italy in proportion to the fall in value of the currency. France 
 and Italy, it is said, are buying an increasing amount of oil from 
 Algiers and Tunis because the relatively high value of the peseta 
 causes the Spanish oil tc be higher in price than the North African 
 oils. Thus, the Spanish producer is in a rather desperate marketing 
 situation. 
 
 During the war, Spain had an excellent opportunity to develop 
 export markets, because France and Italy were otherwise occupied. 
 The Spanish Government for a time fostered this development but in 
 1918 became alarmed at the increasing exportation and placed an 
 embargo on exports in order to protect the domestic supply. This 
 
Circular 279] OLIVE OIL IN SOUTHERN EUROPE 5 
 
 embargo proved fatal to further expansion of Spanish export markets 
 for the reason that the war closed in 1918 and France and Italy again 
 entered the world markets before Spanish exporters could recover 
 from the effects of the embargo. 
 
 In November, 1923, Spanish oil refineries and factories had on 
 hand a large surplus of oil from, the previous season, produced at high 
 prices and salable only on a falling market. The tendency appeared 
 to be to hold the oil and to refuse to sell except at prices that would 
 at least return the wartime production cost. American Consul 
 Burdette of Seville recommended sale at world market prices of this 
 "hold over" oil even at a loss in order to reestablish Spanish oil in 
 export markets and assure future markets for the oil. 
 
 (b) France. — France does not produce enough olive oil for its own 
 needs. Consequently much oil is imported, largely by Marseilles, for 
 refining and blending. During the war, peanut oil was blended with 
 olive oil to replace imported olive oils (unobtainable in sufficient 
 quantity at that time). The blend was well received and became 
 popular. According to refiners and dealers interviewed in Marseilles, 
 the use of this "table oil" blend, consisting of about 75 per cent pea- 
 nut oil and 25 per cent olive oil, is increasing — so that France is 
 becoming less dependent upon imported olive oil. 
 
 In Spain the olive industry is expanding — in France, on the other 
 hand, according to J. Bonnet, Director of the Olive Service of France, 
 the area planted with olives is decreasing because olives give a smaller 
 return to the grower than do some other crops. The substitution of 
 peanut oil for olive oil at a price much below that of olive oil is also 
 a factor. 
 
 (c) Italy.- — The Italian grower is usually also an oil maker and 
 sells oil rather than fruit — in this respect differing somewhat from the 
 French and Spanish growers. Figure 2 illustrates a typical farmer's 
 oil factory building. He produces most of his other necessary food, 
 such as wheat, vegetables, etc., and is usually not so dependent upon 
 the return from his olives as is the grower in some other countries. 
 Farm and olive factory labor costs have not risen so high as in France 
 and Spain — consequently the Italian oil maker can produce more 
 cheaply than his Spanish and French competitors. For these reasons 
 the Italian growers of oil olives and the refiners, as well, appear to be 
 in a better position economically than in the other countries visited. 
 
 3. Cooperative Factories. — At one time most of the Spanish and 
 French oils were made in small factories owned and operated by 
 individual farmers. This is still true of manv sections of Italv. 
 
6 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 In recent years many cooperatively owned factories have been 
 erected, particularly in northeastern Spain and in the Marseilles- 
 Nimes-Aix-en-Provence area of southern France. Several were 
 visited. In all cases the machinery was of the best and apparently 
 the plants were intelligently operated. The cooperative movement is 
 being fostered by the French and Spanish governments. Certain 
 government experts assist in organizing the cooperatives, and others 
 in erecting, equipping, and operating the plants. 
 
 A typical cooperative in Tortosa has about 150 members, many of 
 which formerly operated small mills. The olives are now brought to 
 a central factory in Tortosa, where each member's olives are kept 
 separate and the yield and quality of the oil of each determined. Pay- 
 
 Fig. 2. — Small olive oil factory near Florence, Italy. 
 
 ment is made accordingly. Cooperative manufacture has improved 
 the average quality of the oil and cooperative marketing has strength- 
 ened the growers' marketing position. 
 
 In southern Spain the large privately owned factory and the indi- 
 vidual grower's mill, rather than cooperatives are the rule. Probably 
 the system of holding land in very large estates, as contrasted with 
 the numerous small orchards of northern Spain and southern France 
 account for this difference in ownership of factories. 
 
 4. Costs. — While the costs of production in Spain, France, and 
 Italy have increased greatly during the past ten years, they are still 
 considerably less than in California. 
 
 (a) Spain. — The price asked for oil olives in Seville in October, 
 1924, was 15 pesetas per fanega (about $43.75 per ton), but Consul 
 Burdette reported that the average price paid at harvest was $28.30 
 per ton (about 10 pesetas per fanega). 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 A report by the Spanish Government in 1923 gives the cost of 
 growing olives and making oil in the various provinces. The following 
 cost sheet for Huelva is typical. 
 
 TABLE 3* 
 Cost of Growing Olives in Huelva, Spain (1922) 
 
 Item 
 
 Cost per 
 
 hectare of land 
 
 in pesetas 
 
 Cost per acre 
 
 Pesetas 
 
 Dollars 
 
 Plowing 
 
 Cross plowing 
 
 Cleaning 
 
 Pruning 
 
 Guarding 
 
 Taxes 
 
 Rent 
 
 Harvesting 
 
 Rolling 
 
 Transporting 
 
 Interest on capital 
 
 Total 
 
 32.00 
 28.00 
 16.00 
 
 5.85 
 
 7.50 
 
 27.00 
 
 120.00 
 
 40.50 
 
 9.00 
 11.00 
 
 9.80 
 
 12.9 
 
 11.4 
 
 6.4 
 
 2.4 
 
 3.0 
 
 10.9 
 
 48.6 
 
 16.5 
 
 3.7 
 
 4.4 
 
 3.9 
 
 1.80 
 
 1.60 
 
 .90 
 
 .34 
 
 .42 
 
 1.52 
 
 6.80 
 
 2.31 
 
 .52 
 
 .62 
 
 .54 
 
 306.65 
 
 124.1 
 
 $17.37 
 
 Yield: 19 quintals of olives, 4180 lbs., per hectare, or about 1700 
 lbs. per acre. Cost, 16.14 pesetas per quintal, or $20.46 per ton. 
 
 TABLE 4 
 Manufacturing Cost — Province of Huelva, Spain 
 
 Item 
 
 Cost per 
 
 quintal of oil, 
 
 pesetas 
 
 Cost per 
 
 gallon of oil, 
 
 dollars 
 
 Fixed costs; taxes, insurance, etc 
 
 Power 
 
 Wages, 2 mill men at 4 pstas 
 
 Wages, 2 other men at 3.5 pstas.. 
 
 Other charges 
 
 Olives, 6.25 quintals 
 
 Crushing 
 
 Total 
 
 29.25 
 12.00 
 8.00 
 7.00 
 3.50 
 100.87 
 4.06 
 
 166.68 
 
 $0 . 140 
 .057 
 .040 
 .035 
 .017 
 .484 
 .020 
 
 793 
 
 Minus value of pomace, 1029 lbs. at Sy^c lb. 
 (468 kilograms at .5 pstas) 
 
 Net cost 
 
 25.74 
 140.90 pstas. 
 per quintal 
 
 .123 
 
 $.670 per 
 gallon 
 
 * "El Aceite de Oliva; Besumen hecho por la Junta Consultiva Agronomica 
 de Madrid. 1923." Printed by and obtained from Los Hijos de M. C. Her- 
 nandez, Libertad 16, Madrid, Spain. This report gives a great deal of other 
 valuable information. 
 
8 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Net costs in other provinces were given as shown in the following 
 table : 
 
 TABLE 5 
 
 Relation Costs of Production of Oil in Several Spanish Provinces, 1922 
 (Includes cost of fruit and manufacture) 
 
 Province 
 
 Net cost per quintal 
 in pesetas 
 
 Net cost per gallon 
 in dollars 
 
 1. Huelva 
 
 140.9 
 183.5 
 156.4 
 131.5 
 172.2 
 188.7 
 133.8 
 121.2 
 
 $.670 
 
 2. Jaen 
 
 .881 
 
 3. Granada 
 
 .751 
 
 4. Murcia 
 
 .635 
 
 5. Zaragossa 
 
 .826 
 
 6. Albacete 
 
 .906 
 
 7. Madrid 
 
 .644 
 
 8. Cordova 
 
 .585 
 
 
 
 Average 
 
 153.5 
 
 $.736 
 
 
 
 (b) France. — No data were obtained on manufacturing costs in 
 Prance. The fruit for oil, according to J. Bonnet, Director of the 
 French Olive Service, sold during the 1923 season for 1 franc per 
 kilogram, approximately $43.00 per ton. 
 
 (c) Italy. — The charge for making oil for the grower in several 
 factories visited near Florence was 6 per cent of the oil produced. 
 With a factory value of 75c per gallon this corresponds to a cost of 
 4%c per gallon for crushing and pressing. However, in this case the 
 olives were furnished by tenants and the oil mill was owned by the 
 landlord, who took as rent half the oil. Wages were low in this fac- 
 tory, 10 lira a day, approximately 45c a day for men. Women were 
 paid 3-4 lira, about lSy 2 c to 18c a day, for picking olives. 
 
 CULTURE 
 
 The culture of olives for oil making is similar to that of olives for 
 pickling, as described in Circular 278, "Olive Pickling in Mediter- 
 ranean Countries." Therefore, this information will not be repeated 
 here. In oil olive orchards, however, the trees are generally not so 
 well cared for as in orchards producing pickling olives and inter- 
 cropping is more prevalent. 
 
 In the culture of olive trees in Italy, intercropping is very common. 
 Since this phase of olive culture was not discussed in the report noted 
 above, a brief description of this practice in Italy will be presented. 
 
Circular 279] OLIVE OIL IN SOUTHERN EUROPE 9 
 
 According to Dore, in 1922 of the total olive area in Italy, 4,226,000 
 acres produced other crops in addition to olives and 1,433,000 acres 
 (about one-third of the total area) produced olives only. This con- 
 dition explains Italy's relatively low yield of olives per acre. The 
 trees are usually planted farther apart in orchards where intercrop- 
 ping is practiced. Hay, grain, and grapes are the most common inter- 
 crops, although near the large cities vegetables are often grown 
 between the rows. The farmers admit that dual cropping is not 
 beneficial to the trees, but say that they must intercrop in order to 
 obtain other necessary foods. 
 
 The olive fly is a very serious pest in some of the oil producing 
 regions of southern Europe, notably in the Tortosa-Reus district of 
 northern Spain, the Tuscany region of central Italy, and the Nice 
 district of France. The fly larvae, where infestation is severe, render 
 the fruit soft and "worm-eaten," thus permitting rancidification of 
 the oil in the fruit. Oil from such fruit is high in free fatty acid and 
 of very poor flavor. As noted in the publication on olive pickling 
 in southern Europe (Circular 278), the governments of southern 
 European countries are expending a great deal of money and effort 
 to devise and apply control measures. At present the Berlese method 
 of spraying the trees frequently with a sweetened arsenical spray is 
 the most promising, but has not given very satisfactory control. 
 
 OIL VARIETIES OF OLIVES 
 
 The pickling varieties of olives, such as the Sevillano, Ascolano, 
 Lucques, and Santa Catarina, are considered inferior to certain other 
 varieties that are more generally used for oil making. Nevertheless, 
 limited quantities of cull pickling olives are used for oil. 
 
 (a) Spain. — In Andalusia (southern Spain) the Zorzaleiia is the 
 most important oil variety. The fruit is of larger average size than 
 most oil olives, crops are large and regular and the quality of the oil 
 is good. The trees produce denser foliage than Sevillano trees and 
 more bearing wood is left in pruning than upon Sevillano and Man- 
 zanillo trees grown in the same orchards. The fruit resembles the 
 Mission olive somewhat in appearance, although smaller. In addition 
 to its value for oil making the Zorzalena is of fair pickling quality, 
 and is used extensively for the preparation of salt cured olives, for 
 domestic consumption. According to the former American Consul 
 of Seville, W. T. Gracey, the Zorzalena and Nevadillo Negro may be 
 the same variety; the name varying according to the locality where 
 grown. 
 
10 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 The Lechin ("milk olive") is also an important variety — one that 
 is very rich in oil. The tree is resistant to frost. 
 
 The Nevadillo Blanco is an early variety grown extensively in the 
 provinces of Cordoba, Jaen and Cadiz — important oil producing 
 provinces. The crops are large and the fruit exceptionally rich in oil. 
 The Nevadillo Negro yields excellent oil and is said to give a larger 
 yield of oil from a given weight of fruit than any other variety in 
 Jaen province. This is said by some to be the same as the Zorzalena, 
 In the province of Seville the plantings consist of the following 
 varieties : 
 
 Zorzalena* 70 per cent 
 
 Lechin 12 per cent 
 
 Gordal (Sevillano) 10 per cent 
 
 Manzanillo 7 per cent 
 
 Other varieties 1 per cent 
 
 In the Tarragona district (Tortosa, Tarragona, Barcelona, Reus) 
 varieties other than those listed above are grown. The Arbequina, 
 Morruda, Sevillenca, Grossal, and Farga are probably the most im- 
 portant. Many other varieties are grown, among them the Verdal, 
 Verdarola, Curibella, Palomar, Beearnda, and Vera, Some of these 
 varieties are grown in other districts under other names, it being 
 characteristic of Spanish growers to vary the name of the variety 
 according to the locality. Thus, according to W. T. Gracey, former 
 American Consul of Seville, the Zorzalena of Andalusia is known as 
 Hoji blanca in Alicante and Cadiz; the Negrito y Lucio in Granada; 
 the Moradillo in Almeria ; Gordal in Avila; Zorzalena and Cordobes 
 in Badajoz ; Nevadillo in Cuidad Real : and so on for other provinces. 
 Similarly Italian and French varieties are grown and known by 
 various names according to the locality. 
 
 Literally hundreds of varieties are grown for oil and the nomen- 
 clature is correspondingly extensive and involved. 
 
 See figure 3 for appearance of important Spanish oil olives. 
 
 (b) France. — In the olive oil factories visited in Aix-en-Provence 
 and Nimes the principal varieties observed were those used for 
 pickling, e.g., the Picholine, Lucques, and Verdal. These are 
 described briefly in Circular 278. Other important varieties listed by 
 de Mazieresf ere Rouget, Pigale, Calletier, Pendoulier, Oliviere, and 
 Salonenque. 
 
 * These figures are given in a report by the Spanish Government, 1923, and 
 entitled "El Aceite de diva." (See page 43.) 
 
 t de Mazieres, A. E. La Culture de 1 'Olivier. J. B. Bailliere et Fils, Paris, 
 publishers. 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 11 
 
 (c) Italy. — There are a great many varieties of olives grown for 
 oil in Italy; no less than three hundred varieties according to Aloi.* 
 The College of Agriculture at Florence has recommended the follow- 
 ing varieties for planting for oil making in central Italy : the Cor- 
 regiolo or Frantoio, the Leccino (said to be the same variety as the 
 Lechin of Spain), and the Morinello. Other important varieties grown 
 in Italy are the Corniola, Taggiasea, Pignola, Colombaia, Ogliaia, 
 Caltabellotese, Agostino, Biancolilla, Casertana, and Rasciola. 
 
 Fig. 3. — Oil olives of northeastern Spain. 
 No. 1, Arbequina; No. 2, Farga; No. 3, Morruda; No. 4, Sevillenca. 
 
 (d) Suitability for California. — It is doubtful whether it would be 
 advisable to import European oil olive varieties for growing in Cali- 
 fornia, because our industry is based upon the production of pickled 
 olives. However, the oil made from our Mission olives is considered 
 excellent. The oil olives are in general small and therefore unsuitable 
 for commercial pickling. While the quality of our oil would be 
 improved by growing these varieties, it would probably be impossible 
 
 *Ant. Aloi, l'Olivo e Olio (Milan). 
 
12 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 for Caliiornian growers and oil makers to compete with the Europeans 
 in price. 
 
 However, it is believed that one or more of the dual purpose 
 varieties suitable both for oil making and pickling, such as the French 
 Verdal and Picholine, the Italian Agostino or the Spanish Rapasayo, 
 might find a place in California olive culture similar to that now held 
 by the Manzanillo and Mission. 
 
 Fig. 4. — Harvesting olives for 
 oil, Spain. 
 
 Fig. 5. — Ladder used in north- 
 ern Spain for harvesting olives. 
 Central leg is on a pivot. 
 
 HARVESTING, TRANSPORTING AND STORING THE OLIVES 
 
 Harvesting, transporting, and storing olives for oil making are now 
 given much more consideration than formerly, because the refiners who 
 buy much of the oil from the mills and the government olive oil experts 
 have impressed upon the grower and mill operator the effect of these 
 important preliminary steps on quality and price. 
 
 (a) Harvesting. — The harvesting of olives for oil begins early in 
 November in southern Spain, while in northern Spain, southern 
 France, and central Italy the season is about one month later and 
 extends to about February 1 or later. Olives were being crushed on 
 February 28 in a factory visited near Florence, Italy. 
 
 All mill operators interviewed stated that they wished the fruit 
 to be black in color when harvested for oil. J. Bonnet, Director of 
 the French Olive Service, has found that the oil is of best quality 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 13 
 
 when made from fruit in which the flesh has become purple. Before 
 this stage he finds the oil acrid and of poor flavor ; beyond this stage 
 the oil is apt to be flat in flavor and light in color. Very little of the 
 fruit observed in Spanish, French, and Italian factories conform to 
 Mr. Bonnet's ideal-— much of it was overripe, shriveled, or frosted. 
 
 Harvesting as observed in these countries is conducted in one of 
 three ways : The .first of these consists in picking from the ground 
 fruit which has fallen naturally or which has been knocked from the 
 tree by light poles or rakes. Insects, particularly the olive fly, cause 
 
 Fig. 6. — Shipping oil olives in bags, Spain. 
 
 considerable fruit to fall prematurely, and the first picking usually 
 consists of such fruit. It makes an inferior oil. While government 
 oil experts and others condemn the method of harvesting by knocking 
 the fruit from the trees because of injury to both fruit and bearing 
 wood, it is nevertheless a very common practice. (See figure 4.) 
 
 Knocking the fruit on to burlap or canvas sheets is a method of 
 harvesting practiced in a number of orchards. A great many leaves 
 and small twigs fall with the olives and must be removed by hand or 
 by a fanning mill. Leaves are objectionable because of the green 
 coloring matter (chlorophyll) and acrid compounds dissolved from 
 them by the oil. 
 
 The third method, hand picking from the tree, is of course the 
 best, but not so generally used as might be expected. 
 
 Baskets or sacks suspended from the neck are generally used in 
 preference to metal buckets for holding the fruit during picking. 
 Three-legged ladders such as that shown in figure 5 were seen in many 
 orchards. Large two handled baskets and sacks are used for holding 
 
14 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 the fruit after picking: baskets are preferable but more costly and 
 difficult to handle. 
 
 (b) Transportation. — To most of the factories visited the fruit 
 was delivered in burlap bags. These containers, while cheap and con- 
 venient, are conducive to bruising and are therefore condemned by 
 olive oil authorities. In southern Spain the olives are generally hauled 
 in bulk in large ox-carts lined with grass matting— each cart holding 
 about a ton of fruit — or in angorillas (side bags) on donkey-back. Bags 
 are used for transportation by rail. (See figure 6; also illustrations 
 in Circular 278.) 
 
 
 Fig. 
 
 -Storage bins for fresh olives in oil factory near Seville. 
 
 (c) Storage. — At one time, storage of the olives in deep bins to 
 undergo fermentation and softening before crushing was an almost 
 universal practice in Spain, according to several oil makers who were 
 questioned on this point. At present the trend is away from this 
 practice and toward the use of fruit direct from the orchard before it 
 has had time or opportunity to mold or ferment. 
 
 Nevertheless, deep bins are still common in the less modern factories 
 and are still in use in many of them. A typical bin observed in a 
 small factory is shown in figure 7. The fruit undergoes fermentation 
 in the lower depths of the bin and molding near the surface — a small 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 15 
 
 stream of "black liquor" of rancid odor trickles from the outlet, and 
 the general condition of the fermenting and rotting mixture is bad. 
 Oil from fruit handled in this way has been shown to be high in free 
 fatty acid; it is of poor flavor and often of very "rancid" odor. 
 However, the binning treatment facilitates pressing and makes possible 
 the pressing of a relatively large amount of fruit with a small amount 
 of equipment by prolonging the season. Oil from such factories is 
 generally cheap and finds a local undiscriminating market. In fact, 
 some "hardened" consumers state that they prefer such oil because 
 of its ' ' distinctive ' ' flavor. 
 
 
 i 
 
 ft*. 
 
 ^ ^ 
 
 Fig. 8. — Mill and oil storage jar of the ancient Romans. 
 Pompeii, Italy. 
 
 Storage of the fruit in sacks is little better than in deep bins. 
 Much fermented and moldy fruit was observed in such containers. 
 
 Storage in shallow bins on the floor level, with occasional shoveling 
 over of the fruit, was in use in many factories with apparently good 
 results. Such bins are convenient in cooperative plants where each 
 member's fruit must be kept separate and where several days' delivery 
 from one grower is necessary to give enough fruit for a run in the mill. 
 
 Bonnet (Director of the French Olive Service) and others stated 
 that storage in brine (5-6 per cent salt, 20-25° salometer) is the best 
 
16 
 
 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 method for long storage periods, and that if properly applied does not 
 injure the quality of the oil. This agrees with California experience. 
 All who were questioned, however, agreed that the ideal method is 
 to crush and press on the day of picking. One factory in Spain, the 
 Union Oliverera of Carmona (makers of oil for H. J. Heinz Co.) 
 make a feature of this practice. No fruit is stored. The delivery of 
 each day is crushed and pressed on the day or night of delivery. This 
 practice has made it necessary to install considerably more equipment 
 than would otherwise be required, but it is believed that the high 
 quality of the oil and the correspondingly high price more than offset 
 the extra cost. 
 
 Fig. 9. — Mule drawn mill in farmer's olive oil factory, near Seville. 
 
 EXTE ACTION OF THE OIL 
 
 Crushing and pressing machinery varies greatly in design and 
 efficiency, and mills and presses similar to those used by the ancient 
 Romans are to be found near mills with the most modern equipment. 
 Figure 8 illustrates an ancient oil mill and oil storage jar at Pompeii. 
 
 1. Crushing.. — In small mills in Andalusia, Spain (Seville, Cordova, 
 Jaen, and at other places) will be found the so-called Andalusian 
 single roll, truncated cone edge runner (mule or ox drawn), such as 
 is shown in figure 9. The fruit is fed in slowly from a small hopper 
 above the edge runner. As the latter revolves in the stone or concrete 
 basin, the olives are crushed and forced outward to the circular trough 
 shown in the figure. If insufficiently crushed the fruit is shoveled 
 beneath the edge runner to be crushed a second time. The pomace, 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 17 
 
 after the first pressing, is also often ground beneath this edge runner 
 before the second and third pressing. 
 
 In the Tarragona district a single, very heavy edge runner of the 
 form shown in figure 10 is used in the small mills. One crushing is 
 sufficient, because the fruit is fed in front of the wheel only as rapidly 
 as it can be ground thoroughly. Electricity is the usual power, 
 although animal power is also common. 
 
 Fig. 10. — Single wheel edge runner, Tortosa, Spain. 
 Common in mills in northeastern Spain. 
 
 In the modern mills in Andulusia, rolls of the appearance shown 
 in figures 11 and 12 are used. Three truncated cones of granite 
 revolve in a steel or stone bowl. In addition the two-wheel Italian 
 style of edge runner is used to complete the grinding started in the 
 three-roll mill or to regrind the pomace. (See figures 11 and 12.) 
 According to the report of the Spanish Government previously re- 
 ferred to (see page 43), the capacities of the different types of Spanish 
 mills are for a one-roll mill -10 quintals (8800 lbs.) in 24 hours; two- 
 roll mill, 60 quintals (13,200 lbs.), and three-roll mill, 80 quintals 
 (17,600 lbs.) in 24 hours. 
 
 In the larger factories the olives, before going to the edge runner, 
 usually are ground in a "trituradora," a machine consisting essenti- 
 ally of two horizontal and parallel screws, revolving toward each 
 other. The treatment, it is claimed, increases the capacity of the 
 edge runner and the yield of oil. As in California, fruit in some 
 
18 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 factories goes direct to the press from the "trituradora" or its 
 equivalent. In France, the olives are usually given a preliminary 
 crushing between fluted, steel rolls. These rolls accomplish about the 
 same effect as the Spanish "trituradora" mentioned above. The 
 olives are then ground in an edge runner consisting of two heavy, 
 granite "bull wheels" revolving in a steel bowl. The French edge 
 
 Fig. 11. — Andalusian edge runner with three rolls. 
 In a modern factory, Carmona, Spain. 
 
 runner is very similar in appearance to that in use in Calif ornian 
 olive oil factories. According to Chappelle and Ruby* the Labin and 
 Druge crusher, consisting of eight fluted cylindrical rolls in super- 
 imposed pairs, crushes the olives sufficiently to permit pressing with- 
 out treatment in an edge runner. It may be used also to replace the 
 edge runner in grinding the pomace after the first pressing. 
 
 * Chapelle, J. and Ruby, J. L 'Huilerie Moderne. Published by Librairie 
 Polytechnique. Ch. Beranger, Editeur, 15 Rue des Saints-Peres, Paris. (Out of 
 print.) 
 
Circular 279] OLIVE OIL IN SOUTHERN EUROPE 
 
 19 
 
 n 
 
 Fig. 12. — View of an oil factory near Seville. 
 At left, pomace breaker. At right, three roll edge runner, 
 
 Fig. 13. — Two types of Italian olive edge runners, near Florence. 
 Both driven by water power. 
 
20 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 The crushing methods observed in small Italian factories were 
 similar to those previously described for northern Spain. The mills 
 are shown in figure 13. The crusher in most factories visited con- 
 sisted of a single granite "bull wheel" or edge runner, revolving in 
 a stone bowl, and was operated by animal power or water power. In 
 the larger mills the crushing equipment is similar to that used in 
 France, the edge runners being of the two-wheel type and power 
 driven. 
 
 Fig. 14. — Hand-power press in small Italian factory near Florence. 
 
 2. Presses. — The simplest press seen in use was the hand operated 
 wooden screw press of Italy, shown in figure 14. The lever of the 
 press shown in the illustration was turned by four men who received 
 45c a day each. 
 
 The beam press of the Romans is used in many small mills in Spain. 
 The press consists of a large square wooden bean about 35-40 feet 
 long, pivoted at one end and fitted with a long, vertical, wooden screw 
 at the opposite end. Beneath the press near the pivot end is situated 
 the floor of the press, on which rest the cloths filled with crushed olives. 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 21 
 
 (See figure 15.) Both of these presses are inefficient and give low 
 yields of oil, although they are simple and inexpensive. 
 
 Various styles of metal, hand power screw presses are also used 
 in many small factories. 
 
 Hydraulic presses are almost universally used in the large fac- 
 tories. These are similar to those used in Californian factories, 
 although some of the French hydraulic presses give considerably 
 higher pressure than is normally obtained in either Spain or Cali- 
 fornia, See figures 16, 17, and 18 for appearance of typical presses. 
 
 Fig. 15. — Beam press used in small factories of southern Europe. 
 (After Chapelle and Ruby.) 
 
 3. Pressing and Regrinding. — Press "cloths" are usually made of 
 woven esparto grass or coconut fiber. (See figure 19.) Camel's hair is 
 used in some factories for the second and third pressings if very heavy 
 pressure is to be applied. The press cloths are usually circular and 
 about 27-30 inches in diameter. For hydraulic presses they are often 
 made with a hole in the center through which the central steel post 
 of the press is passed. The edges of each cloth ("capacho" in Spanish, 
 "scourtin" in French) are turned inward for about three inches 
 (see figure 19) so that when one is placed above another a tight seal 
 is made around the edges. 
 
 The ground olives from the edge runner are shoveled or scooped 
 with the hands into the press cloth in place in the press or on a 
 portable press floor, and the ground mass is then spread into place with 
 
22 
 
 UNIVERSITY OF CALIFORNIA- — EXPERIMENT STATION 
 
 the hands. The filled cloths are built up one above the other to give 
 the "cheese" as shown in figures 14, 17, and 18. 
 
 The first pressing (in whatever manner applied) removes most of 
 the easily expressable juice, together with some oil, This first oil, 
 "virgin" oil, is considered the best and is kept separate from the 
 second and third pressings. 
 
 Pig. 16. — Hydraulic olive press in action, Tortosa, Spain. 
 
 The pomace is in Spain and Italy reground before the second 
 pressing. The Spanish pomace grinder consists of a cylinder fitted 
 with spikes and which revolves toward a plate also fitted with spikes. 
 This machine is known as a "remoledora." In many factories, par- 
 ticularly small ones, the pomace is ground in an edge runner. In 
 such cases, a small amount of water is often added to the pomace from 
 the first pressing. Water is always added before the third pressing. 
 The addition of water before the second pressing is condemned by all 
 European olive oil authorities interviewed ; but if water is to be added, 
 these experts agree that cold water is preferable to warm, because it 
 dissolves less of the objectionable compounds from the pulp. 
 
Circular 279" 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 23 
 
 In France two pressings only are used in the modern factories 
 visited, and the pomace is not ground between pressings. A moderate 
 pressure is first applied to remove most of the juice. The cloths are 
 then transferred to the second press without disturbing the press 
 cakes, and very heavy pressure applied. The yield, according to J. 
 Bonnet, is excellent, the final pomace containing only 8 per cent of 
 oil or less. The secret of success in this method lies in the use of a 
 very powerful press for the second pressing. (See figure 18.) Labor 
 costs are materially cut and the capacity of the presses considerably 
 increased by this method. 
 
 Fig. 17. — Upper, Hydraulic pumps with variable speed drive. Lower, line-up 
 of presses and crushers. Both views in a modern factory, Spain. 
 
 In Spain three pressings are given. In the small factories in 
 central Italy, three pressings arc also applied, and then the pomace 
 from the third pressing is ground in water in an edge runner, as 
 shown in figure 20, until the pulp is thoroughly disintegrated. This 
 water, with suspended pulp, flows to several settling tanks, shown in 
 figure 20, and eventually to a stream. Oil rises in the various tanks 
 and is recovered by skimming or overflow. The ground seeds and 
 settlings are removed from the bottom of the first tank periodically. 
 Figure 20 illustrates this system of pomace treatment. The oil is of 
 very poor quality, but often suitable for refining. If too rancid for 
 refining, it is always salable for soap stock. Chappelle and Ruby (see 
 
24 
 
 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 previous reference, page 43) state that 2 to 5 per cent of oil is recover- 
 able by this method. Much higher yields can be obtained by treating 
 the pomace with an oil solvent (see page 37). 
 
 4. Separating Oil and Juice. — In all of the Spanish and Italian 
 oil factories visited, the mixed juice and oil from the press are allowed 
 to settle and are then separated by decantation or by skimming. In 
 the modern Spanish factories glazed tile line tanks receive the liquid 
 
 JLfdiizer 
 
 Fig. 18. — High pressure hydraulic press used in Frr 
 (After Ohapelle and Euby.) 
 
 *e for second pressing. 
 
 from the press. Two or more of these tanks are connected in series 
 by syphons extending nearly to the bottom of each tank. The oil rises 
 to the surface and is removed through an opening near the top of the 
 tank. This separator may be operated continuously. (See figure 21.) 
 
 In small factories that were visited the mixed liquids were placed 
 in tanks and after settling the oil was separated by skimming by hand. 
 
 Tin-lined, sheet metal tanks fitted as shown in figure 22 were 
 observed in Spain. Similar tanks have been used in some California 
 factories. Separation may be made either intermittent or continuous 
 
Circular 279] OLIVE OIL IN SOUTHERN EUROPE 
 
 25 
 
 Fig. 19. — Esparto grass press bag ("Capacho "), Spain. 
 
 ^rox ***** 
 
 Fig. 20. — Equipment used in Italy for recovery of oil from pomace by grind- 
 ing in water and flotation. (After Chapelle and Ruby.) A, edge runner. B, 
 Stirrer. C, Tanks for separation of oil and water, a, Connecting conduit. 
 c, Water inlet, h, Stirrer. I, Waste skins and pulp. 
 
26 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 In France separation of the oil and juice by centrifugal force is 
 rapidly displacing other methods. The machine is similar in appear- 
 ance to a milk separator and operates on the same principle. The 
 liquid from the press is elevated to a small tin-lined tank, into which 
 it flows through a fine screen which removes particles of pulp, skin, 
 etc. Unless removed, this solid matter quickly clogs the bowl of the 
 separator. The bowl of the machine in most common use (the Turbina 
 Hignette) revolves at from 6000 to 10,000 r.p.m., according to its 
 diameter. Separation is instantaneous, continuous, and complete. 
 Settling, decantation, and skimming are dispensed with. The oil 
 makers who were interviewed expressed full approval of the machine 
 and the process. Centrifugal separation is in use in at least one 
 California factory and it is possible that others could use it with 
 advantage. 
 
 5. Other Methods of Extracting Oil. — In addition to the standard 
 methods described above, several methods are in use in southern 
 Europe or have been used experimentally. 
 
 (a) Continuous press. — One of the most promising of these is the 
 Colin method in which a continuous press is used. This consists of 
 two screws revolving in a perforated, horizontal cylinder, with an 
 outlet into which fits an adjustable metal cone. The size of the outlet 
 and thereby the pressure, can be adjusted by adjusting the position 
 of the cone. In experiments this machine has given pomace contain- 
 ing only 7 per cent of oil, indicating unusually high extraction. The 
 difficulty has been to separate the emulsified oil and juice — the 
 machine grinds the pulp very fine, making a mixture of pulp, oil, and 
 juice that settles with great difficulty. Chappelle and Ruby (see 
 reference, page 43) believe that this difficulty can be overcome. A 
 continuous, mechanical process that wiir eliminate hand labor is highly 
 desirable for use in California. Such a press has recently been 
 designed and built by the California Press Manufacturing Company, 
 and is said to have given good results in commercial size experiments. 
 
 (b) Acapulco process. — Professor Don Guillermo Quintanillo has 
 experimented with this process and when interviewed at the National 
 School of Agriculture in Madrid reported that it is now in successful 
 operation in a factory in southern Spain. Other Spanish, French, and 
 Italian olive oil experts who were consulted did not consider the 
 process very practical. It has been greatly simplified by Quintanillo 
 and others, and may eventually come into general use. 
 
 The process as originally conducted consisted in pitting the olives ; 
 grinding the pulp to a fine paste; placing this paste in a horizontal 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 27 
 
 cylinder under a high vacuum, where it was rubbed against a very 
 fine cylindrical screen, which permitted the oil to pass but which 
 retained the pulp and juice. The vacuum has been found unnecessary 
 and is no longer used. The pitting machine and grinder have been 
 replaced by a single machine which removes the pits and converts the 
 olive flesh into a fine pulp. It was understood from Professor 
 Quintanillo that this machine is similar to a tomato pulper. It has a 
 capacity of about 30 tons a day. 
 
 Fig. 21. — Glazed tile tanks for separation of oil and juice 
 in a modern mill, Spain. 
 
 The oil separating machine consists of a. metal cylinder, the lower 
 half of which is a hemicylindrical sheet of nickel with very fine 
 perforations. Brushes attached to a central shaft revolve slowly, 
 8-10 r.p.m., and bring about the separation previously mentioned. 
 Professor Quintanillo states that the separation is accomplished 
 essentially by filtration "in motion" and that it depends very largely 
 upon the difference in surface tension of olive oil and water. Accord- 
 ing to Quintanillo, the experimental plant has a capacity of 18,000 
 kilograms, nearly 20 tons, in 24 hours. 
 
28 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 He claims for it the following advantages : 
 
 1. Greater yield of oil than by pressing. 
 
 2. Better quality of oil — all being of virgin oil quality. There is 
 but one grade. 
 
 3. Lower acidity. 
 
 4. Greater economy of operation and far greater capacity per unit 
 of power expended. 
 
 5. Less skill and experience required. "Anyone can make good 
 oil with this process. ' ' 
 
 6. Less space required for equipment. 
 
 7. Greater simplicity of operation. 
 
 8. Obtaining a valuable stock food as a by-product. 
 
 A commission appointed by the Spanish Department of the Interior 
 reported favorably upon the process. Professor Quintanillo informed 
 the writer that he is glad to give further information. 
 
 (c) Centrifugal Separation of Pulp and Oil. — This has been tested 
 and although partial success was attained, the method has not been 
 perfected, insofar as J. Bonnet, Director of the Olive Service of 
 France, Professor Quintanillo of Madrid, Dr. Matons of the University 
 of Barcelona, and others were aware. 
 
 (d) By Diffusion. — According to Chappelle and Ruby (see page 
 43), oil may be extracted by diffusion. In one method of applying 
 the diffusion principle the olives are ground to a paste, mixed with a 
 salt solution (sea-water will do), and heated with agitation for several 
 hours. The oil rises and the pulp sinks. The yield is said to be 
 greater than by pressing, but the heating injures the quality. 
 
 Professor Bracci of Spoleto, Italy has varied this procedure by 
 substituting a dilute alkaline solution for the brine and subjecting 
 it to an electric current. The mixture is kept at 40° C. (104° F.). 
 
 While the diffusion process is still of doubtful value ,it might prove 
 worthy of further investigation. 
 
 (e) By Solvent. — Trichlorethylene, "trielene, " is a cheap, non- 
 inflammable oil solvent and by its use it is possible to prepare an edible 
 oil from suitably dried olives. According to Dr. Matons, in charge of 
 olive oil investigations at the University of Barcelona, this method 
 has been applied successfully at an olive experiment station in Italy. 
 One difficulty is economical drying. Another is complete separation 
 of the solvent and oil by distillation. Treatment under a high vacuum 
 with steam is said to remove all trace of the solvent. Dr. Matons did 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 29 
 
 not believe the method very practicable from a commercial standpoint. 
 The solvent process is to be tested in Los Angeles during the present 
 season, according to a letter recently received from the owner of the 
 solvent equipment. 
 
 OIL and WATER 
 
 WATER 
 
 FOAM 
 
 fVAM 
 
 Fig. 22. Oil and juice separator used, in Spain. 
 (From "Boletin Mensual de Olivicultura. ") 
 
 NORMAL TREATMENT OF THE OIL 
 
 The treatment of the oil varies somewhat according to the country, 
 the district, and the manufacturer. 
 
 1. Washing.— Washing the oil with water, as practiced in all fac- 
 tories in California, is by noi means general in Mediterranean oil mills. 
 In fact, in the majority of factories visited the oil was not washed 
 with water at all, and aging and filtration were relied upon to remove 
 the bitterness. In France washing with sprays of water (cold recom- 
 mended in preference to warm) is a more common practice than in 
 Spain. Spanish olive oil authorities who were consulted advised 
 against washing of the oil because it removes desirable flavors and 
 aroma. 
 
30 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Washing if applied, is conducted as in California, by sprays of 
 water. In one small factory the water was added from an ordinary 
 garden sprinkling" pot. The washed oil must be allowed to settle and 
 then be thoroughly separated from the sediment, or filtered to remove 
 all water — otherwise, bacterial growth and rancidification will ensue. 
 A temperature above 55° F. and below 70° F. is recommended during 
 settling. At lower temperatures the oil is viscous and separation is 
 imperfect; above 70° F., rancidification is favored. After the water 
 in the oil has been completely removed, the storage temperature is not 
 so important, 
 
 2. Storage. — In large factories tanks lined with glazed tile are 
 generally used. These are often beneath the floor and of very large 
 capacity. In many small factories, particularly in Spain, stoneware 
 jars such as those shown in figure 23, and in others tin-lined cylin- 
 drical tanks are used. See figure 23. The tile-lined (sometimes called 
 "glass-lined") tanks are easily cleaned with dilute lye solution and 
 can be kept in sound condition. Tin also is easily cleaned, but the 
 pores of the stoneware jars seen in several factories had become 
 impregnated with oil which had become very rancid and odoriferous. 
 A good interior glaze is essential for such containers. 
 
 The temperature recommended for the storage room is above 40° F. 
 and below 60° F. Below 40° F. the solid fats are apt to separate ; 
 when redissolved in the oil it is claimed that they impart a "tallowy" 
 taste. Above 60° F., danger of rancidification increases. However, 
 very few of the factories visited would be able to maintain this tem- 
 perature range. Rather frequent rackings, that is drawing off the oil 
 from the "foots" (sediment) are made in most factories because the 
 foots tend to decompose and cause increase of acidity. In one large, 
 modern factory in southern Spain, very large, underground, tile- 
 lined storage tanks are used and the oil frequently racked until it is 
 free from bitterness — a year or longer being required. At no time is 
 the oil washed in this factory. 
 
 Storage tanks should be of such design that, when filled, as small 
 a surface of oil as possible is exposed to the air in order to reduce 
 oxidation. 
 
 3. Filtration. — Many different styles of filters are in use. In the 
 large refineries plate and frame filter presses consisting of metal racks 
 and canvas filter cloths are used because of their great capacity. The 
 oil in such plants is mixed with a "filter aid" such as infusorial 
 earth or with a bleaching material such as fuller's earth or decoloriz- 
 ing carbon. 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 31 
 
 The most popular filter in factories of large and moderate size 
 appeared to be a so-called "capillary" filter using" discs of filter paper 
 held between circular metal plates, placed one above the other to form 
 a vertical cylinder. This filter produces a brilliantly clear oil, is 
 simple in operation, easily assembled and portable. A small rotary 
 pump may be used to deliver the oil to the filter under constant pres- 
 
 Fig. 23. — Tin-lined tanks and large earthenware jars used for 
 oil storage in a factory near Seville. 
 
 sure, or the oil may be allowed to flow by gravity from a supply 
 tank placed 15 to 25 feet above the filter. The Daude filter of Le 
 Vigan (Gard), France, is of the capillary type. See figure 24. 
 
 Other filters used are made up of metal plates between which are 
 placed compressed pads of cotton fiber which serve as the filtering 
 medium. The Vail filter of Barcelona is of this type. 
 
32 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 Homemade filters consisting of a box with a layer of cloth covered 
 cotton can be found. Porous earthenware vases or tubes are also in 
 use for small scale filtration. Funnels and folded filter paper are 
 not used as commonly as in California. 
 
 Any form of open filter, such as a funnel and paper, exposes a 
 large surface of oil to the air, for a relatively long time, resulting in 
 loss of flavor, absorption of odor and oxidation, Such filters are con- 
 demned for these reasons bj^ European oil authorities such as Matons 
 of Spain and Bonnet of France. California oil manufacturers will 
 do well to investigate the French "capillary" filter and other forms 
 of European and American oil filters with a view to replacing the 
 present filter paper and funnel system of filtration. 
 
 4. Demargination. — Demargination consists in the removal of an 
 excess of dissolved solid fats. According to J. Bonnet, Director of 
 the Olive Oil Service of France, and Professor Matons of Barcelona, 
 European oils are not demarginated, except to the extent that occurs 
 naturally during normal storage of the oil. At low storage tempera- 
 tures a considerable amount of solid fat (stearin) separates and is 
 removed by racking. As stated elsewhere, it is considered desirable 
 by some oil makers to remove any solid fat that may separate during 
 storage because of the development of a "tallowy" taste, which is 
 said to ensue if the fat is redissolved. However, in one large oil 
 refinery and cannery, oil which had partially congealed by cold during 
 shipment in steel drums was thoroughly melted before canning, thus 
 redissolving the solid fats. The flavor of the oil was excellent. There- 
 fore, there is some doubt as to the truth of the statement that redis- 
 solved solid fats impart a "tallowy" taste. 
 
 In northern Africa it is stated by Chappelle and Kuby (see refer- 
 ence, page 43) that some of the oil is artificially chilled to cause 
 separation of the solid fats and is then filter pressed to remove them 
 from the oil. Oil from olives grown in very hot districts, according 
 to Bonnet, contain much more stearin than those grown in cooler 
 climates — this explains the difference in treatment in southern Europe 
 and northern Africa. 
 
 5. Oil Standards. — In Spain, the writer was informed by Dr. 
 Aguilo, Director of the Olive Oil Station and Laboratory of Tortosa, 
 three general grades of oil are recognized in the Spanish trade : fine oil 
 ("aceite fino") containing less than 1% per cent of free fatty acid 
 and of fine flavor and odor; common oil ("aceite corriente") with less 
 than 5 per cent of free fatty acid and of fair quality, and sub-standard 
 oil with more than 5 per cent of free fatty acid or oil below this 
 
Circular 279] 
 
 OLIVE OIL IN SOUTHERN EUROPE 
 
 33 
 
 acidity, but otherwise unsuitable for food purposes on account of 
 objectionable flavor or odor. The sub-standard oil can often be 
 refined and blended with better oils — as a matter of fact, this is very 
 common practice. Oil from olives badty infested with the larvae of 
 the olive fly is usually sub-standard and may often contain 15 to 20 
 per cent of free fatty acid, making it fit only for soap stock. Oil 
 extracted from the pomace with carbon bisulfid or other solvent is 
 also sub-standard and usually suitable only for soap stock. 
 
 Fig. 24. — French upright type olive oil filter press using paper discs. 
 
 Olive oil is bought and sold on analysis as well as on flavor and 
 odor. The refiners, who are also the principal dealers, pay the oil 
 manufacturer according to the acidity of the oil — the price rapidly 
 decreasing as the acidity increases. Color standards are also observed 
 in the refineries, and the final products so adjusted by refining and 
 blending that an oil of a given grade will be uniform in color from 
 year to year. 
 
34 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Calif or nian oil makers should adopt standards of acidity and 
 color — there is altogether too much variation in these respects in our 
 oils at present. The acidity is easily determined as follows : 
 
 Place 50 c.c. of alcohol in a beaker (denatured alcohol will do). Add a few- 
 drops of phenolphthelein indicator. From a burette add, drop by drop, barely 
 enough tenth normal sodium hydroxide to cause the color to become permanently 
 pink. With a clean pipette add 10 c.c. of oil and stir with a glass rod to 
 dissolve. Take reading on the burette containing the tenth normal sodium 
 hydroxide. Add the hydroxide solution slowly at first, and finally very slowly, 
 drop by drop, constantly stirring with a glass rod, until a, permanent pink color 
 is obtained. Eead the burette. Subtract the first reading from the second. The 
 difference is the amount of sodium hydroxide in cubic centimeters used to 
 neutralize the oil. Multiply this figure by 0.282. The result will be " grams of 
 free fatty acid per 100 cubic centimeters (300 c.c.) of oil" and is usually 
 understood as "per cent." To obtain actual per cent, that is grams of free 
 fatty acid per 100 grams of oil, multiply the " grams per 100 c.c." by 1.3. 
 
 A good oil should contain less than 1.5 per cent free fatty acid. 
 
 Doubtful samples should be submitted to a reliable commercial 
 analyst. 
 
 6. Packaging. — Olive oil, both crude and refined, is transported in 
 steel drums such as are used in America for gasoline and engine 
 distillate. Apparently tin is not essential. Wooden barrels are also 
 used. 
 
 In the large oil refineries cans are made and lithographed on the 
 premises from sheet tin imported from England or northern Spain. 
 The large can factories such as exist in America are not common in 
 European countries. 
 
 The oil is filtered just before canning or bottling in order to give 
 it a ''polish," that is, to make it brilliantly clear. The acidity of 
 canned oil must be low in order to avoid action on the metal with 
 consequent development of a green color. Cans are filled by weight 
 and bottles to a uniform height. Great care is taken to see that the 
 containers are thoroughly dry when filled. Moisture causes cloudiness 
 and spoiling. 
 
 "Sulfur oil" (by-product olive oil) is exported in steel drums or 
 in wooden barrels, table oils in smaller containers of tin or glass. 
 
 EEFINING TPTE OIL 
 
 The refining and blending of olive oil has become a very important 
 industry in Spain, France, and Italy. Many olive oils require refining 
 before they can be used for food — many others of edible quality are 
 greatly improved by refining. Marseilles in France, Seville, Cordoba, 
 and Reus in Spain, and Genoa in Italy are important refining centers. 
 
Circular 279] olive oil in SOUTHERN EUROPE 35 
 
 Refining consists in removing excessive free fatty acid, excessive 
 color and objectionable odors and tastes. Methods vary somewhat in 
 the different refineries, but the basic principles applied are the same 
 in all. 
 
 1. Deacidifieation. — The removal of the excess of free fatty acid is 
 the first treatment. The acidity of the oil is determined by titration. 
 A measured volume of oil is placed in the neutralizing tank, which 
 in the factories visited consists of a steam-jacketed, tin-lined, steel 
 tank of cylindrical shape and fitted with an agitator. The agitator in 
 one instance was a small propellor similar to those used on small 
 motor boats. This was placed at one side and near the bottom of the 
 tank. 
 
 To the oil is added the amount of sodium hydroxide solution (soda 
 lye) found necessary by analysis, to neutralize the free fatty acid of 
 the oil. According to Dr. Fachini, Chief of the Oil School of Milan 
 University, Italy, a lye solution of 17° Baume is suitable. A refiner 
 stated that the lye solution used in his refinery is 12° Baume. To 
 neutralize 1 per cent of free fatty acid (1 gram per 100 c.c.) there 
 would be required 1 gallon of lye solution of 12° Baume or % gallon 
 of 17° Baume for 100 gallons of oil. Other acidities would require 
 lye in proportion. If the lye solution is too dilute a troublesome 
 emulsion will form. 
 
 The mixture is stirred and heated until reaction is complete. 
 According to Dr. Fachini the temperature should reach about 165° F. 
 
 The free fatty acid and lye combine to form soap. This being 
 heavier than the oil settles out and can be separated by settling and 
 drawing off. The settling takes place in tanks with conical bottoms. 
 Filtration is necessary if the settling is not complete. 
 
 2. Removal of Excess of Color. — This follows deacidification. 
 Fuller's earth is used in most refineries, although in a Spanish 
 refinery visited in Seville, decolorizing carbon, presumably boneblack, 
 was used. Finely ground fuller's earth or finely ground vegetable 
 or animal charcoal is mixed with the oil and the oil heated and stirred 
 in a steam-jacketed tin-lined tank. The amount of decolorizing agent 
 required varies greatly according to the depth of color and degree of 
 decolorizing required. In experiments in the Fruit Products Labora- 
 tory 1 to 3 per cent by weight gave satisfactory results. 
 
 The length of treatment was not learned but in experiments in the 
 laboratory most of the decolorizing effect was obtained by one hour's 
 heating at 160° F. ; very little additional action was obtained by 
 heating longer. 
 
36 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 The hot oil is filtered in plate and frame filter presses through 
 canvas. The press cake may be treated with a solvent to recover the 
 residual oil. 
 
 3. Deodorizing. — The oil is now practically free from fatty acid 
 and usually almost water white in color, but often of disagreeable odor. 
 It is well known that superheated steam passed through an odoriferous 
 oil will volatize the odor producing compounds. If, however, this is 
 conducted at atmospheric pressure, the high temperature attained, 
 together with the moisture, will "crack" the oil, that is, cause for- 
 mation of glycerine and free fatty acid. The flavor aLso will be 
 injured. 
 
 But if the oil is placed under a high vacuum and superheated 
 steam is passed through it, the temperature remains low, e.g., 150° F. 
 or less, because the steam expands tremendously in the vacuum and 
 therefore drops in temperature. Consequently, there is little injurious 
 effect of heat. At the same time the volatility of the odorous com- 
 pounds is greatly increased and these are carried off, practically 
 completely, by the steam. 
 
 The deodorizers seen and those described and sketched for me by 
 Ed. Battaile & Co. of Paris consist, first, of a steam- jacketed vacuum 
 pan, presumably tin lined. This is connected to a barometric con- 
 denser and high duty, dry-vacuum pump. The second feature is the 
 steam supply. Steam is passed through a superheater placed near 
 the vacuum pan. This is merely a pipe surrounded by a jacket con- 
 taining high pressure steam. Superheating increases the temperature 
 of the steam above that at its saturation point. It, therefore, enters 
 the vacuum pan in a "dry" state, free of condensed vapor. It also, if 
 superheated, expands to a greater volume in the vacuum pan than 
 would otherwise be the case and thereby exerts greater effect on 
 removal of volatile odors. The steam passes into the condenser, where 
 a spray of water condenses it to water, which overflows from the con- 
 densate tank at the foot of the barometric condenser. The vacuum 
 pump removes air and other gases and should maintain a vacuum of 
 27-28% inches. 
 
 4. Refining Experiments in Fruit Products Laboratory. — Four 
 one-quart samples of rancid, odoriferous oil were treated in glass flasks 
 by the foregoing processes of deacidification, decolorizing, and de- 
 odorization by steam in vacuo. Deacidification was conducted with 
 calculated amounts of 10 per cent sodium hydroxide solution. 
 Decolorizing was accomplished by heating with 2 per cent by weight 
 of Darco vegetable decolorizing carbon. The treated oil was filtered 
 
Circular 279] olive oil IN SOUTHERN EUROPE 37 
 
 through paper after addition to the oil of 1 per cent by weight of 
 "Filter-Cel." The deaciclified, decolorized sample was placed in a 
 flask; a vacuum of 28 inches applied and steam passed through at 
 160° F. The steam was not superheated, hence did not exert as high 
 deodorizing power as could be obtained by superheating. Nevertheless, 
 three of the samples were deodorized sufficiently by 15 minutes' treat- 
 ment — the fourth retained some of its objectionale odor after 15 
 minutes' steam treatment, although greatly improved. 
 
 UTILIZING THE BY-PEODUCTS 
 
 The principal by-products from olive oil factories is the pomace 
 (press cake). Of less importance are the foots (settlings from 
 storage tanks) and the "black liquor" or juice from the oil and juice 
 separators. 
 
 1. Oil from Pomace. — The pomace from efficient presses contains 
 only 8 per cent or less of oil ; imperfectly pressed pomace may contain 
 12 per cent or more. As described elsewhere, page 23, the pomace may 
 be ground in water by an edge runner and 2 to 5 per cent of oil 
 recovered by flotation in water. Much higher yields are obtained by 
 drying the pomace and extracting it with a volatile solvent. 
 
 The solvent most commonly used is carbon bisulfide. This is a 
 volatile, very inflammable liquid, heavier than water, and possessing 
 high oil solvent properties. 
 
 Benzol, a volatile liquid obtained as a by-product from coke ovens 
 and gas plants, is also used. It is less volatile and therefore less 
 dangerous than carbon bisulfide, but more costly. 
 
 Gasoline and benzine are also used successfully. 
 
 Recently a non-inflammable solvent, trichlorethylene, known in 
 commerce as ' ' trielene ' ' has come into use in France through the work 
 of J. Bonnet, Director of the Olive Service. 
 
 It is possible to completely remove any of the above solvents from 
 the oil by distillation, to recover most of the solvent followed by treat- 
 ment of the residual oil in vacuo with superheated steam as in refining. 
 If the pomace is treated fresh, within a day or two after pressing, an 
 edible oil containing less than 5 per cent free f atty acid can be obtained. 
 The pomace should therefore be delivered to the extractor as soon as 
 possible. If more pomace is delivered than the extractor can care for, 
 the excess should be dried and held until the end of the season and 
 the extractor operated to capacity on fresh pomace in order to obtain 
 the maximum of oil of low acidity. 
 
38 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 Drying was accomplished in one factory visited in France by con- 
 ducting the ground pomace by means of a screw conveyor through an 
 open steam-jacketed metal trough. In a large refinery in Spain dry- 
 ing was done in a rotating metal drum through which passed a blast 
 of hot air. Inexpensive drying methods must be used as the product 
 is of low value. In another plant the pomace was spread in the sun 
 or on a concrete floor to air dry. This method is slow and permits 
 molding, souring, and rancidification. Artificial heat is therefore to 
 be preferred. 
 
 The extractor observed in a Spanish factory consisted of the fol- 
 lowing parts: (a) an extracting tank, (b) still, (c) condenser, and 
 (d) reservoir. The dried pomace was placed in the extracting tank 
 which was then filled with solvent from the reservoir. This was 
 allowed to remain a short time and was then drawn off into the still. 
 Here it was volatalized and condensed above the extracting tank into 
 which it flowed, dissolved for more oil, and returned to the still. This 
 cycle was continued until the pomace was practically exhausted of 
 oil. Steam was then turned into the pomace in the extractor and most 
 of the remaining solvent recovered by distillation. Carbon bisulfide 
 was used as a solvent, 
 
 The extractor seen in an oil factory in Nimes, France, was operated 
 in a similar manner, except that tricblorethylene was used as a solvent. 
 This solvent boils at 86-87° C. (186.8-188.6° F.). Since trichlore- 
 thylene is non-inflammable and less volatile than carbon bisulfide, it is 
 a very suitable solvent. Although it is higher in price than most other 
 commercially used solvents, the amount lost in operation is not so 
 great that the price is prohibitive. According to J. Bonnet, about 
 1.3 gallons is lost per ton of pomace. According to Batataile & Co., 
 manufacturers of solvent equipment, in Paris, about 1.5 gallons is lost 
 per ton. 
 
 At the time of the writer 's visit the price for this ' ' trielene ' ' was 
 given by Mr. Bonnet at 2.5 francs per kilogram, or about 6 1 /2C per 
 pound or about 45c per gallon. With pomace containing 8 per cent of oil 
 on the wet basis — about 12 per cent on the dry basis — and a recovery 
 of 10 per cent on the dry basis, the yield of oil would be 200 pounds 
 per dry ton or about 27 gallons. The cost of the solvent would then 
 be, if 2 gallons per ton were lost (% gallon more than Battaile Co. 's 
 estimate) 90c per ton or about 3 1 />c per gallon of oil recovered. To 
 this, of course, must be added the cost of handling, interest on invest- 
 ment, depreciation, etc. Experience at Nimes, according to J. Bonnet, 
 has shown these costs, plus cost of solvent lost, to be about 220 francs 
 
CIRCULAR 279] OLIVE OIL IN SOUTHERN EUROPE 39 
 
 per 4000 kilograms of pomace or about $2.50 per ton of pomace. This 
 plant has a capacity of 4.4 tons of pomace per day. 
 
 The equipment need not be expensive if made from galvanized 
 sheet metal and iron steam pipe. In fact any sheet metal shop could 
 make up a simple outfit from published sketches and descriptions. 
 
 Possibly one such plant in each of the important oil districts of 
 the state would be profitable. 
 
 2. Pomace for Stock Feed. — Extracted pomace is not suitable for 
 stock feed. Fresh pomace, according to Professor Mantons, taken 
 before it has molded or soured may be put through a machine consist- 
 ing of a disintegrator, screen and fan, which separates the pits from 
 the skins and pulp. The pulp is a fairly good stock feed and the pits 
 may be used as fuel or may be distilled to give charcoal, wood alcohol, 
 and acetic acid. 
 
 3. Use of Black Liquor. — The juice from the separating tanks, or 
 centrifugals is usually discarded. In one large factory, however. I 
 was told that this juice is allowed to stand in shallow open air vats. 
 Some oil is recovered by skimming and the juice evaporates, leaving 
 a residue with considerable fertilizing value. This treatment can be 
 given only in semi-arid districts. 
 
 4. Foots. — The foots, settlings from the oil storage tanks, as in 
 California is sold for soap stock. 
 
 SUMMARY AND CONCLUSIONS 
 
 1. Olive oil is a staple food in southern Europe and its manu- 
 facture a basic food industry. The situation in California is different 
 in these respects. Here olives are grown principally for pickling, the 
 production of a luxury. 
 
 2. The total acreage of olives in France, Greece, Italy, Portugal, 
 Spain, Algeria, and Tunis in 1922 was over 11,750,000, according to 
 Dore of the International Institute of Agriculture of Rome. If 
 Turkey, Palestine, etc., are included the total would exceed 12,000,000 
 acres. Italy leads with 5,659,000 acres, and Spain is second with 
 4,102,000 acres, according to Dore's report. 
 
 3. Production in individual countries varies greatly from year 
 to year, but for the Mediterranean region as a whole has been fairly 
 constant from 1911 to 1922, inclusive. It is, therefore, advisable to 
 discount reports made before harvest of crop shortages or abnormally 
 large crops in various Mediterranean countries. 
 
40 UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION 
 
 4. The Spanish olive oil industry was not prosperous at the time of 
 the writer's visit, because of poor export demand occasioned by un- 
 favorable exchange rates between Spain and Italy and France, and by 
 the Spanish Government's embargo on the export of olive oil during 
 the last year of the World War. The embargo prevented Spain's 
 retaining her export market developed during the war. France and 
 Italy still import Spanish oil for blending purposes, although increas- 
 ing quantities are now imported from northern Africa. In France and 
 Italy the oil industry appeared to be in a much better economical 
 condition; nevertheless the cost of production of oil has risen out of 
 proportion to the returns. 
 
 5. Many cooperative oil factories are in successful operation and 
 are being built in Spain and France. These are replacing the 
 numerous individual farm mills. The oil made in the cooperative 
 plants is much better than that made in the antiquated, unsanitary 
 farm outfits. The respective governments are furnishing every 
 possible aid to these cooperatives. 
 
 6. According to a recent report of the Spanish Department of the 
 Interior, the average cost of producing oil, including the cost of 
 the olives, was, for eight leading oil producing provinces, $.736 
 (American) per gallon. In France it is probably about equal to the 
 Spanish cost; in Italy it is less. 
 
 7. The growing of olives for oil is similar to that for pickles as 
 described in Circular 278 of this Station. However, pruning of oil 
 olive trees in Spain is less severe and the orchards are given less care 
 because of the smaller financial returns from oil olives. 
 
 8. In southern Spain the Zorzalena (probably the same as the 
 Nevadillo) is the most important variety of oil olive; in northern 
 Spain the Arbequina. In France dual purpose olives are grown to 
 a greater extent than in Spain or Italy; thus the Picholine and 
 Verdal are planted extensively for both pickling and for oil. Perhaps 
 the Picholine or some other variety suitable for both pickling and oil 
 making would prove desirable in California for similar use. In Italy 
 the varieties are multitudinous in number. 
 
 9. Harvesting olives for oil is done less carefully than in Cali- 
 fornia, the fruit usually being knocked or stripped from the trees on 
 to the ground or on to sheets. All European authorities agree, how- 
 ever, that hand picking from the tree is greatly to be preferred to 
 other methods. 
 
 10. The olives are usually transported in sacks, in which sweating, 
 heating, and fermentation frequently occur. Baskets are preferable. 
 
Circular 279] OLIVE OTL IN SOUTHERN EUROPE 41 
 
 11. Storage of the olives in deep bins was at one time a common 
 practice but is being replaced by storage in shallow piles and frequent 
 stirring to minimize decomposition before pressing. Pressing within 
 twenty-four hours after harvest is the best practice, and is followed in 
 the best Spanish factories. 
 
 12. The olive fly is a serious pest in several oil districts, particu- 
 larly in the Tarragona-Tortosa district of Spain and in Tuscany in 
 Italy. Over 90 per cent of the fruit becomes infested in some seasons, 
 so injuring the quality of much of the oil that it must be used for 
 by-product purposes. The infestation of oil olives is more severe than 
 that of pickling olives because the former hang on the tree one to 
 three months longer. 
 
 13. Crushing and pressing equipment and methods are not radi- 
 cally different from those in California. In France only two pressings, 
 and without removal of the pulp from the press cloths, are given — the 
 second pressing being at higher pressure than in other countries. This 
 method reduces labor costs and equipment. Several new methods of 
 oil extraction are under investigation. Of these the Acapulco process 
 seems to have made' the most progress. It consists in separating the 
 oil from the pulp and water by rubbing the finely ground pulp against 
 a very fine nickel screen. A continuous press (the Colin) also is said 
 to give good results. Probably modifications of one or more of these 
 new methods would be useful in California as a means of reducing 
 costs and increasing yields and perhaps quality. 
 
 14. Centrifugal separation of oil and ' ' black liquor ' ' has come into 
 general use in France as a substitute for settling and decantation or 
 skimming. The new method is spreading also to Spain and Italy. 
 
 15. Oil is not washed to the extent practiced in California. Spanish 
 oil makers prefer not to wash the oil at all, but to remove bitterness 
 by long storage, settling, and racking. Washing removes desirable 
 odors and flavors. 
 
 16. Demargination is not practiced except in northern Africa for 
 oils very rich in solid fats. 
 
 17. Glass lined or glazed tile lined tanks are preferred for storage, 
 although tin lined tanks and large earthen jars are in common use in 
 small factories. 
 
 18. Filters are usually of the filter press type — these use cloth in 
 some cases, although the apparently most popular filter press uses 
 discs of specially prepared paper. The funnel and paper filter is con- 
 demned because it exposes a large surface to oxidation, permits undue 
 loss of flavor and aroma, and exposes the oil to the danger of con- 
 
42 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 
 
 lamination by foreign odors. California oil makers should investigate 
 and try the European methods of nitration. 
 
 19. Much oil is refined in large, centrally located refineries in 
 Seville, Reus, Marseilles, Genoa, and elsewhere. Oil that would other- 
 wise be inedible because of high acidity or disagreeable flavor and 
 odor is made by refining into a light colored, mild oil suitable for 
 blending purposes. Refining usually consists in neutralizing the free 
 acid by a sodium hydroxide solution (soda lye), removing excess of 
 color with fuller's earth or decolorizing carbon, and deodorizing by 
 treatment with superheated steam in vacuo. Part of this process, 
 deacidification and decolorizing, can be accomplished in Calif ornian 
 factories with the present equipment; deodorization would require 
 special equipment, although this need not be very expensive. 
 
 20. The pomace is utilized throughout the olive oil region of the 
 Mediterranean for the recovery of the residual oil. Solvent treating 
 plants purchase the pomace at prices remunerative to the oil factories 
 or the larger factories operate their own solvent plants. Carbon 
 bisulfide is the usual solvent, but trichlorethylene is coming into use 
 because of its non-inflammability. A dry ton of California pomace 
 should yield at least 25 gallons of oil or a fresh ton 20 gallons by 
 solvent extraction. At 50c a gallon this would return $10 to $12.50 
 a ton. The extracted pomace would still be suitable for fuel. Whether 
 the treatment of the pomace would prove profitable in California is 
 an open question. It is at least worthy of investigation. 
 
 21. Olive oil is bought and sold in Europe on definite standards. 
 Free fatty acid is the most important basis of judgment of quality — 
 color is also very important. California oil manufacturers would do 
 well to adopt definite standards for color and free fatty acid in order 
 that the oil would have a more definite standing in the trade. 
 
Circular 279] OLIVE OIL IN SOUTHERN EUROPE 43 
 
 LIST OF SELECTED REFERENCES 
 
 i El Comercio de Aceites en Espafia, by L. A. Lamarca. Published by Libreria 
 Calpe, Madrid. 
 
 2 El Aeeite de Oliva, Resumen hecbo por la Junta Consultiva Agronomica de 
 
 Madrid, 1923. Printed and obtainable from Los Hijos de M. C. Her- 
 nandez, Libertad 16, Madrid, Spain. Cost about $3.00. 
 
 3 Boletin Mensual de Olivicultura. Published monthly by Don Isidoro Aguilo, 
 
 Jefe de Estaeion Olivera, Tortosa, Spain. 
 
 4 P. d 'Aygalliers, L 'Olivier et l'Huile d 'Olive. Published by J. B. Bailliere 
 
 et Fils, 19 Rue Haute Feuille, Paris. Price, 50 francs plus postage; total 
 about $3.00. An excellent book, 
 s J. Bonnet, L'Olivier. (1924.) The same publisher and price as reference 
 No. 4. An excellent book and up to date. 
 
 6 J. Chappelle and J. Ruby. l'Huilerie Moderne. Published by Librerie Poly- 
 
 technique, 15 rue Saints-Peres, Paris. Out of print. The best book in 
 French on oil. 
 
 7 Les Matieres Grasses. Monthly journal on oils. Published by A. D. Gillard, 
 
 Les Matieres Grasses, 49 rue de Yinaigriers, Paris. Price, 36 francs per 
 annum. About $2.10. 
 
 s La Revue Oleicole, published monthly. 71 rue de la Procession, Paris. Price, 
 15 francs per annum plus postage; total about $1.25. Covers olives and 
 oil. 
 
 » Dore, Valentino. Oleaginous Products and Vegetable Oils. (Statistical.) 
 Published by the International Institute of Agriculture, Villa Borghesi, 
 Rome. (1923.) Very good. Price not known but probably less than 
 $2.50. 
 
 io L'Industria degli Olii e dei Grassi (Italian). Published by Dottore S. Fachini, 
 R. Laboratoria Olii e Grassi, Via Marina 5, Milan, Italy. Postpaid, 60 
 lira per annum ($3.00.) Published monthly. 
 
 ii A. Cravino and A. Zuccarello. Come produrre dell 'olio migliore nel Meridi- 
 onale. 10 lira (50c). Fratolli Ottari, Casale, Montferrat, Italy. 
 
STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION 
 
 BULLETINS 
 No. No. 
 
 253. Irrigation and Soil Conditions in the 346. 
 
 Sierra Nevada Foothills, California. 347. 
 
 261. Melaxuma of the Walnut, "Juglans 
 
 regia." 348. 
 
 262. Citrus Diseases of Florida and Cuba 349. 
 
 Compared with Those of California. 
 
 263. Size Grades for Ripe Olives. 350. 
 268. Growing and Grafting Olive Seedlings. 351. 
 273. Preliminary Report on Kearney Vine- 352. 
 
 yard Experimental Drain. 
 
 275. The Cultivation of Belladonna in Cali- 353. 
 
 fornia. 354. 
 
 276. The Pomegranate. 357. 
 
 277. Sudan Grass 
 
 278. Grain Sorghums. 
 
 279. Irrigation of Rice in California. 358. 
 
 280. Irrigation of Alfalfa in the Sacramento 
 
 Valley. 359. 
 
 283. The Olive Insects of California. 360. 
 
 285. The Milk Goat in California. 
 
 286. Commercial Fertilizers. 361. 
 
 287. Vinegar from Waste Fruits. 
 
 294. Bean Culture in California. 362. 
 
 298. Seedless Raisin Grapes. 363. 
 
 304. A Study of the Effects of Freezes on 
 
 Citrus in California. 364. 
 
 310. Plum Pollination. 
 
 312. Mariout Barley. 366. 
 
 313. Pruning Young Deciduous Fruit Trees. 
 
 317. Selections of Stocks in Citrus Propa- 367. 
 
 gation. 
 319. Caprifigs and Caprification. 368. 
 
 321. Commercial Production of Grape Syrup. 
 
 324. Storage of Perishable Fruit at Freezing 369. 
 
 Temperatures. 370. 
 
 325. Rice Irrigation Measurements and Ex- 371. 
 
 periments in Sacramento Valley, 
 1914-1919. 372. 
 
 328. Prune Growing in California. 
 
 331. Phylloxera-Resistant Stocks. 373. 
 
 334. Preliminary Volume Tables for Second- 374. 
 
 Growth Redwood. 
 
 335. Cocoanut Meal as a Feed for Dairy 
 
 Cows and Other Livestock. 375. 
 
 336. The Preparation of Nicotine Dust as 
 
 an Insecticide. 376. 
 
 339. The Relative Cost of Making Logs from 
 
 Small and Large Timber. 377. 
 
 340. Contrel of the Pocket Gopher in Cali- 378. 
 
 fornia. 
 
 343. Cheese Pests and Their Control. 
 
 344. Cold Storage as an Aid to the Market- 
 
 ing of Plums. 
 
 Almond Pollination. 
 
 The Control of Red Spiders in Decidu- 
 ous Orchards. 
 
 Pruning Young Olive Trees. 
 
 A Study of Sidedraft and Tractor 
 Hitches. 
 
 Agriculture in Cut-over Redwood Lands. 
 
 California State Dairy Cow Competition. 
 
 Further Experiments in Plum Pollina 
 tion. 
 
 Bovine Infectious Abortion. 
 
 Results of Rice Experiments in 1922. 
 
 A Self-mixing Dusting Machine for 
 Applying Dry Insecticides and 
 Fungicides. 
 
 Black Measles, Water Berries, and 
 Related Vine Troubles. 
 
 Fruit Beverage Investigations. 
 
 Gum Diseases of Citrus Trees in Cali- 
 fornia. 
 
 Preliminary Yield Tables for Second 
 Growth Redwood. 
 
 Dust and the Tractor Engine. 
 
 The Pruning of Citrus Trees in Cali- 
 fornia. 
 
 Fungicidal Dusts for the Control of 
 Bunt. 
 
 Turkish Tobacco Culture, Curing and 
 Marketing. 
 
 Methods of Harvesting and Irrigation 
 in Relation to Mouldy Walnuts. 
 
 Bacterial Decomposition of Olives dur- 
 ing Pickling. 
 
 Comparison of Woods for Butter Boxes. 
 
 Browning of Yellow Newtown Apples. 
 
 The Relative Cost of Yarding Small 
 and Large Timber. 
 
 The Cost of Producing Market Milk and 
 Butterfat on 246 California Dairies. 
 
 Pear Pollination. 
 
 A Survey of Orchard Practices in the 
 Citrus Industry of Southern Cali- 
 fornia. 
 
 Results of Rice Experiments at Cor- 
 tena, 1923. 
 
 Sun-Drying and Dehydration of Wal- 
 nuts. 
 
 The Cold Storage of Pears. 
 Studies on the Nutritional Disease of 
 Poultry Caused by Vitamin A De- 
 ficiency. 
 
 CIRCULARS 
 
 No. No. 
 
 70. Observations on the Status of Corn 155. 
 
 Growing in California. 157. 
 
 87. Alfalfa. 160. 
 
 111. The Use of Lime and Gypsum on Cali- 161. 
 
 fornia Soils. 164. 
 
 113. Correspondence Courses in Agriculture. 165. 
 117. The Selection and Cost of a Small 
 
 Pumping Plant. 166. 
 
 127. House Fumigation. 167. 
 
 129. The Control of Citrus Insects. 170. 
 136. MeKlotus indica as a Green-Manure 
 
 Crop for California. 172. 
 
 144. Oidium or Powdery Mildew of the Vine. 173. 
 
 151. Feeding and Management of Hogs. 
 
 152. Some Observations on the Bulk Hand- 174. 
 
 ling of Grain in California. 178. 
 
 154. Irrigation Practice in Growing Small 179. 
 Fruit in California. 
 
 Bovine Tuberculosis. 
 
 Control of the Pear Scab. 
 
 Lettuce Growing in California. 
 
 Potatoes in California. 
 
 Small Fruit Culture in California. 
 
 Fundamentals of Sugar Beet Culture 
 
 under California Conditions. 
 The County Farm Bureau. 
 Feeding Stuffs of Minor Importance. 
 Fertilizing California Soils for the 1918 
 
 Crop. 
 Wheat Culture. 
 The Construction of the Wood-Hoop 
 
 Silo. 
 Farm Drainage Methods. 
 The Packing of Apples in California. 
 Factors of Importance in Producing 
 
 Milk of Low Bacterial Count. 
 
CIRCULARS — ( Continued ) 
 
 No. 
 
 184. 
 
 190. 
 
 193. 
 
 198. 
 
 199. 
 
 202. 
 
 203. 
 
 205. 
 208. 
 
 209. 
 210. 
 212. 
 214. 
 
 215. 
 
 217. 
 
 219. 
 
 220. 
 228. 
 230. 
 
 231. 
 232. 
 
 233. 
 234. 
 
 235. 
 
 236. 
 
 237. 
 
 238. 
 239. 
 
 240. 
 241. 
 
 242. 
 243. 
 
 244. 
 
 A Flock of Sheep on the Farm. 
 
 Agriculture Clubs in California. 
 
 A Study of Farm Labor in California. 
 
 Syrup from Sweet Sorghum. 
 
 Onion Growing in California. 
 
 County Organizations for Rural Fire 
 
 Control. 
 Peat as a Manure Substitute. 
 Blackleg. 
 Summary of the Annual Reports of the 
 
 Farm Advisors of California. 
 The Function of the Farm Bureau. 
 Suggestions to the Settler in California. 
 Salvaging Rain-Damaged Prunes. 
 Seed Treatment for the Prevention of 
 
 Cereal Smuts. 
 Feeding Dairy Cows in California. 
 Methods for Marketing Vegetables in 
 
 California. 
 The Present Status of Alkali. 
 Unfermented Fruit Juices. 
 Vineyard Irrigation in Arid Climates. 
 Testing Milk, Cream, and Skim Milk 
 
 for Butterfat. 
 The Home Vineyard. 
 Harvesting and Handling California 
 
 Cherries for Eastern Shipment. 
 Artificial Incubation. 
 Winter Injury to Young Walnut Trees 
 
 during 1921-22. 
 Soil Analysis and Soil and Plant Inter- 
 relations. 
 
 The Common Hawks and Owls of Cali- 
 fornia from the Standpoint of the 
 
 Rancher. 
 Directions for the Tanning and Dress- 
 
 of Furs. 
 The Apricot in California. 
 Harvesting and Handling Apricots and 
 
 Plums for Eastern Shipment. 
 Harvesting and Handling Pears for 
 
 Eastern Shipment. 
 Harvesting and Handling Peaches for 
 
 Eastern Shipment. 
 Poultry Feeding. 
 Marmalade Juice and Jelly Juice from 
 
 Citrus Fruits. 
 Central Wire Bracing for Fruit Trees. 
 
 No. 
 245. 
 247. 
 248. 
 
 249. 
 250. 
 
 251. 
 
 252. 
 253. 
 254. 
 
 255. 
 
 256. 
 257. 
 258. 
 259. 
 260. 
 
 261. 
 262. 
 263. 
 264. 
 
 265. 
 266. 
 
 267. 
 
 268. 
 
 269. 
 270. 
 271. 
 272. 
 
 273. 
 275. 
 
 276. 
 
 277. 
 
 278. 
 
 Vine Pruning Systems. 
 
 Colonization and Rural Development. 
 
 Some Common Errors in Vine Pruning 
 and Their Remedies. 
 
 Replacing Missing Vines. 
 
 Measurement of Irrigation Water on 
 the Farm. 
 
 Recommendations Concerning the Com- 
 mon Diseases and Parasites of 
 Poultry in California. 
 
 Supports for Vines. 
 
 Vineyard Plans. 
 
 The Use of Artificial Light to Increase 
 Winter Egg Production. 
 
 Leguminous Plants as Organic Fertil- 
 izer in California Agriculture. 
 
 The Control of Wild Morning Glory. 
 
 The Small- Seeded Horse Bean. 
 
 Thinning Deciduous Fruits. 
 
 Pear By-products. 
 
 A Selected List of References Relating 
 to Irrigation in California. 
 
 Sewing Grain Sacks. 
 
 Cabbage Growing in California. 
 
 Tomato Production in California. 
 
 Preliminary Essentials to Bovine Tuber- 
 culosis Control. 
 
 Plant Disease and Pest Control. 
 
 Analyzing the Citrus Orchard by Means 
 of Simple Tree Records. 
 
 The Tendency of Tractors to Rise in 
 Front; Causes and Remedies. 
 
 Inexpensive Lavor-saving Poultry Ap- 
 pliances. 
 
 An Orchard Brush Burner. 
 
 A Farm Septic Tank. 
 
 Brooding Chicks Artificially. 
 
 California Farm Tenancy and Methods 
 of Leasing. 
 
 Saving the Gophered Citrus Tree. 
 
 Marketable California Decorative 
 Greens. 
 
 Home Canning. 
 
 Head, Cane, and Cordon Pruning of 
 Vines. 
 
 Olive Pickling in Mediterranean Coun- 
 tries. 
 
 15m-ll,'24