Some of the

Minor importations. As recoverable from domestic crops, they are still in the class of minor oils. It must be borne in mind that the Crops existence of a. potential supply of any given oil does not mean that a profit can be realized by recovering it, even Ernest B. Rester at high market prices. Numerous eco- nomic factors have to be considered. By oils and , w^e usually mean the nonv^olatile oils that occur naturally as In ordinary times we could get along chemical combinations of glycerin and very well with an adequate supply of fatty acids. We shall not consider here the oils and fats from soybeans, pea- the volatile or essential oils that are nuts, cottonseed, corn, and milk^ which valued for their fragrance or flavor, we produce or import in huge amounts. such as peppermint, wintergreen, and But in times of emergency, when out- citronella. Also excluded are certain side supplies are cut off, we must sup- vegetable waxe^s, which in many re- plement our domestic production with spects resemble oils and fats but do not every available pound from every have the glyceride structure. available source. That^ plus the fact Vegetable oils differ from one an- that some oils have properties that other mainly in the kind and amount adapt them to specific uses, is why we of combined fatty acids, and the classes, are interested in minor oil crops. kinds, and amounts of impurities pres- Furthermore, many of the minor ent. Therefore, the properties of the crops can be exploited as small-business various vegetable oils usually differ ventures and may yield a fair return to only in degree, except in a highly in- a few investors who care to go into the dividual oil that contains a large per- vegetable-oil industry with a moderate centage of some unique constituent. outlay for equipment. For example, contains a high The minor vegetable oils fall into percentage of combined ricinoleic acid, four general classes : and tung oil a large amount of eleo- 1. Oils from oil-bearing agricultural stearic acid, neither of which is ordi- wastes, such as fruit pits, tomato pom- narily found in vegetable oils to any ace, wine pomace, and olive marc, and great degree. the seeds of citrus fruits, apples, pears^ Oils are characterized also by their pumpkin, squash, and pimento. . That term the oil tech- 2. Oils from seeds and grains that nologists use to describe the drying mostly are raised as crops, including power, or lack of it, in an oil. High- rice, , sunflower, okra, castor, iodine oils (linseed, walnut, tung) are mustard, rape, and tobacco. usable in paints and other surface coat- 3. Oils of tree nuts—, wal- ings. Those with low iodine values nut, , and filbert. (cottonseed, rice-bran, olive) do not 4. Fruit-flesh oils—olive and avo- form hard films when they are exposed cado. to air. A few of the oils listed are second in importance only to our major bulk oils, THE PIT OILS of the apricot, peach, but that is true only because of sizable prune, and plum strikingly resemble 592 SOME OF THE MINOR OIL CROPS 593 one another in composition and, in- two, crushing the kernel into fragments deed, are not readily difTerentiated. that are hard to recover. Where free- Cherry-pit oil has a somewhat higher stone pits are available, oil recovery is iodine value, These oils arc like sweet- more practical. The kernels, from the almond oil, for which they are some- whole pits obtained from drying yards, times substituted. If the pits are proc- can be separated in the equipment used essed promptly after removal from the for apricot pits. Eleven tons of dry free- fruit, little or no "oil of bitter " stone pits yield about a ton of kernels, will be liberated into the fixed oil by from which about 0.4 ton of oil can be chemical reaction. The pit oils com- pressed. Screw presses can be used, but mand a premium price over the com- the one plant that operated on peach moner vegetable oils and arc usually pits in California employed hydraulic handled by brokers in essential oils. presses used in hot-pressing . Our annual crop of apricots averages Processed cherries, both sweet and more than 240,000 tons, of which more sour, are marketed pit-free as canned, than 80 percent is dried, canned, or frozen, and brined products. The oil otherwise processed. Many growers dry represented by the total of pitted cher- their fruit and sell the pits at attrac- ries amounts to about 1,100 tons a tive prices. Several plants in California year, but no plant at present is recover- shell apricot pits to recover kernels, for ing it. One company in Wisconsin pro- which there is a strong domestic mar- duced a few tons of cherry-kernel oil a ket, particularly for making macaroon few years ago, and another used cherry paste. The dry-pit equivalent for apri- pits as a source of the "oil of bitter al- cots processed each year in the United monds." The operations for recovering States is about 12,000 tons, which cherry-kernel oil are similar to those would yield about 3,000 tons of kernels. used for peach- and apricot-pit oils. In the cracking process, many kernels No fruit pits other than peach, apri- are broken ; they arc used to recover oil. cot, and cherry are likely sources of oil. Our production of apricot-pit oil is Only small amounts of prune pits are about 100 tons a year. It is used largely available for processing because most of for making cosmetics and pharmaceu- the prune crop is marketed without re- ticals. moval of the pits. Volumes of plum Most of the peach crop in the East and date pits from processing plants and Midwest is marketed as fresh fruit. are comparatively small. In pressing Because California produces about 90 olives for oil, the whole fruit, including percent of the peaches processed in the pit, is crushed. In plants where pitted entire country, only there could you olives are canned, the pits are a waste consider peach pits as a source of oil product, but the oil content of 3.5 to 7 and other byproducts. The pits from percent is probably too low for profit- the peaches processed in California able recovery. Inclusion in animal could yield about 1,400 tons of oil a feeds has been suggested, but such a year. At present, peach pits can be ob- material, unless well ground, would tained from canneries and drying yards undoubtedly contain hard, sharp par- for little or nothing except cost of haul- ticles, which might injure the digestive age. A comparatively small proportion tract. of the available pits is converted into The oil of citrus seeds resembles cot- char for poultry feeds and fuel briquets. tonseed oil in general properties. The Very little peach-kernel oil is extracted, approximate amounts obtainable from because most of the pits available for food-processing operations are : Grape- byproducts are from canners' cling- fruit-, 2.600 tons; Valencia stone peaches, which when wet yield orange-seed oil, 1,200 tons; and lemon- less than 1 percent of oil, and because seed oil, 500 tons. many modern canneries use a saw that Florida, Texas, Arizona, and Cali- cuts the entire peach, including pit, in fornia produce grapefruit in commer- 594 1950-1951 YEARBOOK OF AGRICULTURE cial quantities, but only Florida proc- The flourishing wine industry in esses seeded varieties in tonnages large California has made available large enough that the seeds might be consid- quantities of the grape pomace, from ered a practical source of . which seed can be readily separated by One plant in Florida manufactures the either dry or wet methods. At least oil in considerable amounts. three mills in California are now pro- California, Arizona, and Florida ducing grape-seed oil by extraction produce Valencia oranges, the only from the seeds of wine pomace. On the major seed-bearing variety grown in basis of an annual crush of a million this country. The seed content varies tons of grapes, the quantities of recov- greatly. Orange seeds contain about 40 erable oil would be about 3,200 tons if percent of oil, which can be readily ex- all the pomace were processed. Only a pressed or extracted. The oil is easily fraction of the wine pomace is worked refined to a pleasing, light-colored, for oil and byproducts. bland product, useful for foods and Grape-seed oil is excellent for culi- other purposes. nary purposes. As it is semidr\dng, it Lemons, unlike oranges, are not a can be used together with other oils in seasonal crop. Fruit in all stages of paint formulations. ripeness can be found on a tree. It is an interesting fact that a cold snap or SEVENTY PERCENT of domestic ap- freeze will be followed, after an inter- ples used in processing are raised in the val of months, by a crop of lemons that \Vestern States and North Atlantic have an unusually high seed content. States. The seed from the part of the The processing of lemons commercially annual apple harvest that is canned, is confined to southern California. dried, and frozen would yield about More than 90 percent of our grapes 385 tons of oil. Economical recovery, are grown in California, where the however, would be limited to the larger 500,000 acres in vineyards are more districts, in which case the Tnaximum than double the acreage devoted to amount of oil would be reduced to 270 oranges. Here we find principally the tons. Only large packing cent(^rs would \anifera or Old World type of grape. be justified in separating seed from The Great Lakes region is a center for waste and would in most instances dis- the production of the Lubrusca or pose of the seed to oil mills. slipskin type, of which the Concord is California and Washington, centers representative. of production of pears for canning and Grape seeds are available in the drying, account for 90 }XTcent of the wastes from the raisin and the wine in- national total. The output of processed dustries, particularly the latter. In pears in California is roughly double former years, raisins were made almost that of Washington. Not more than exclusively from seed-bearing grapes about 150 tons of oil could be realized (principally of the Muscat variety) ; from pear seeds as a total for both large quantities of seeds, rejected from areas. Apple- and pear-seed oils are drying plants, were used in making oil, quite similar. Both can be refined to a brandy, tartrates, and stock feed. As pale, bland product entirely suitable for the Thompson seedless grape has de- culinary pur]:)oses. \'eloped, the tonnage of Muscats con- The principal cranberry-producing verted to raisins has dwindled, and in States are Massachusetts, New Jersey, 1948 less than 10,000 tons of that va- and W^isconsin. W^ashington and Ore- riety was dried. In terms of vegetable gon account for 3 to 4 percent of the oil, it equals about 45 tons. One plant national total. About a third of the is producing raisin-seed oil by expres- cranberries raised arc made into seed- sion methods. This oil is used in oiling free manufactured products, princi- packaged raisins to make them free pally sauce. The oil yield possible from flowing. the seed rejected in processing would SOME OF THE MINOR OIL CROPS 595 not exceed 50 tons. More valuable grains of okra, asparagus, mustard, than the seed oil is the ursolic acid in rape, safílower, sunflower, castor, rice, the skins. This chemical, in the form and tobacco. of its sodium salt, is a powerful agent Raising okra seed for oil is now ap- for production of water-in-oil emul- proaching a reality, after extensive ex- sions. Neither cranberry-seed oil or perimentation, in several Southern ursolic acid is now in commercial pro- States, notably Louisiana and Texas. duction. Farm-machinery companies are devel- About 2,400 tons of oil a year could oping special combines for harvesting be produced from the tomato waste tfie seed. It is somewhat hard to sepa- discharged from processing plants. rate hulls and kernels of okra seed, Part of the waste is discharged into because the seed is small. Solvent-ex- sewer systems and causes pollution tracted or expressed oil from crushed when it is carried into streams. Ordi- whole seed has a greenish cast, but the nances against such practice are be- color can be bleached. The oil is said coming increasingly severe, and tomato to have good stability after refining and processors are seeking means whereby hydrogénation. the pomace can be converted into Asparagus seed would become avail- products that will at least offset the able in quantity for oil recovery in the cost of handling. Many plants merely San Joaquin and Sacramento delta dry and sell whole tomato pomace for area of California if a practical method feed. Drying, however, is costly because for harvesting it were developed. Cali- of the high moisture content. In one fornia produces about one-half of our plant, seeds arc separated from skins asparagus. The seed contains about 13 and sold for oil recovery. Freshly ex- percent of oil, which is in the drying pressed oil is reddish, but it can be class, although its iodine value, 137, is easily bleached. not high for this type of oil. Tomato canneries are located in Oil obtainable from mustard seed many parts of the country. This lack of grown in the United States amounts centralization and the fact that the to about 6,500 tons. Montana accounts potential supply of tomato-seed oil is for about 78 percent of all the mustard not large mean that oil recovery in grown, the remainder coming from connection with any one plant would California, Washington, Oregon, and probably be uneconomical unless other North Dakota. Three types of -bearing materials were also avail- are grown—oriental, brown, and yel- able for processing. low^ Besides yielding a fixed glyceride The total annual pack of squash and oil, the brown and yellow varieties are pumpkin would yield enough seeds to useful in making condiments. Mustard- make about 500 tons of oil. Centers of seed oil can be used as a supplement processing for the two vegetables are or substitute for oil, because Indiana, Illinois, California, and, to a it has a high content of combined lesser extent, Ohio, Washington, Ore- erucic acid. gon, and New Jersey. None of this oil The United States has imported is being recovered, but in Europe it considerable rapeseed oil in times past, is expressed and put to edible uses. A principally for making special lubri- nutlike delicacy is made by roasting and cants, but the amounts received fell salting kernels of pumpkin seed. from a peak of 15,000 tons in 1942 to Pimento-seed oil has been extracted 2,000 tons in 1948. It contains about from cannery wastes occasionally in 50 percent of combined erucic acid. California plants. The oil content of Some rape is grown in northern Idaho pimento seeds is 19 to 20 percent. It is and eastern Washington, but it is a deep red when first extracted, but it minor crop. can be bleached readily. Safflower has been mentioned by Oils are obtained from seeds and different investigators as a new oilseed 596 1950-1951 YEARBOOK OF AGRICULTURE crop for the northern and western parts killed the plants before harvesting or of the Great Plains. It has been grown where artificial defoliation is practiced. near Dcming, N. Mex., in eastern W^ith the end of the v^^ar, the commer- Washington, and in northern Idaho, cial raising of castor beans dropped, and is now rapidly growing in favor as but in 1948 and 1949 small acreages an oilseed crop in Colorado, California, were planted in Missouri, Oklahoma, Nebraska, and Wyoming. Safflower oil Texas, New Mexico, and California. has drying properties. Extensive tests New areas were in production in 1950. on its use in coating compositions show One castor-oil company has planned to that, when blended with , it make large plantings in the Central improves the resistance of the coating Valley of California. At one time in the to weathering. United States, raising of castor beans Until 1948, practically all the sun- flourished and supported the operation flower-seed oil we used was imported. of numerous oil mills, but the industiy The small amounts of sunflow^er seed had almost died out by 1920. raised previously in the United States Rice bran as a source of vegetable had been used principally in feeds. The oil has certain attractive features: It success of sunñow^er crops in Canada, has a low content of moisture; it is however, in postwar years led to plant- available in large tonnages at central ings in North Dakota for oil produc- locations; it can be solvent-extracted tion. The di^velopment increased the without pretreatment. A disadvantage domestic crop from about 1,200 tons is the difficulty of filtering the oil be- in 1947 to about 10,000 tons in 1948, cause of a waxy sludge that separates and, although it fell to about 5,000 tons from it, and the presence of fine par- in 1949, sunflowers sometimes may be ticles of solid matter. The term "rice an important oilseed crop here. The oil bran" signifies not the seed coat alone is excellent for use in salad oils and but rather a fraction of the rice grain . removed in milling, which includes Castor is a versatile plant. Its leaves also germ and broken grains. The frac- yield ricin, a potent insecticide; its tion contains on an average about 15 stalks, bast fiber and a-cellulosc. The percent of oil, but that value may be oil has a high density and a low con- higher or lower depending on the way gealing point. It is used widely as a con- the rice is milled. stituent of hydraulic-brake fluids, as a Rice oil could be produced in low-temperature lubricant, and as a amounts of 15,000 to 20,000 tons a liquid cushion in artillery recoil mech- year from the combined milling oper- anisms. It has had a place in medicine ations of the South and West. It is now a long time. Early in the Second World solvent-extracted in several plants in W^ar, the Department of Agriculture the United States, including one in fostered the planting of castor on sev- Texas and four in California. One eral thousand acres in Texas. In Flor- other company pressed bran in screw ida, successful test plantings by a com- equipment but recovered only about mercial concern yielded 600 to 900 one-half to two-thirds of the oil. The pounds of beans to the acre. The prob- deoiled bran is more stable than un- lem of raising castor beans domesti- treated bran in that it can be stored for cally in competition with foreign sup- longer periods without rancidifying. It plies has not been completely solved, is an excellent poultry and stock feed principally because of harvesting diffi- and can be used as a source of B culties with mechanical equipment. In vitamins. most strains of castor, the capsules The bran is preferably treated im- holding the beans either drop or shatter mediately after its removal from the when ripe, and for that reason mechan- grain, because the oil is then more ical methods have not superseded readily refined and less is lost to the hand picking, except where frost has soap stock in the process. If stored even SOME OF THE MINOR OIL CROPS 597 for a few days before extraction, rice pharmaceutical industries, where it bran deteriorates to a point at which competes with imported almond oil. the oil is quite high in fatty acids. The The amount of produced oil itself, once it is removed from the in this country is 300 to 600 tons an- bran^ does not exhibit that tendency. nually. Raw material for oil pressing is It is similar in general composition to divided between inedible meats re- cottonseed and peanut oils. jected during shelling and meat frag- One of the largest of the minor ments recovered from shells. One plant vegetable oils in potential volume is ob- in Los Angeles makes most of our wal- tainable from tobacco seed. It has been nut oil. It gets its raw material prin- estimated that at least 13,000 tons cipally from the shelling plant of a could be produced annually from the large cooperative. Screw-press equip- seed that develops on the sucker ment is used. The shell is reduced to growths of tobacco of the flue-cured flours of various screen sizes, which arc type, after the seed heads are topped. sold as soft grit for blast cleaning of Tobacco-seed oil is in the class of dry- metals, as plastic filler, as an ingredi- ing oils. Iodine values as high as 151 ent of nonskid paints, and as a carrier have been reported, although the oil for agricultural insecticides. from our domestic tobacco seed usually Walnut oil is similar to linseed oil. falls wâthin the range of 140 to 146. Before the Second World War it was sold entirely to the coating industry. THE TREE-NUT OILS include almond, Since then it has been consumed also walnut, pecan, and filbert oils. as a food oil. The outlet for walnut We ordinarily think of the tree nuts press cake, which contains a consider- as luxury foods too high in price and able amount of shell, is mainly the too small in actual volume for use as a fertilizer industry, although some was source of vegetable oils. This situation used as stock feed a few years ago. has indeed been true for the most part. are grown in several South- Exceptions were the almond and wal- ern States, principally Georgia, Okla- nut crops of 1949, which were so large homa, and Texas. About 300 tons of that a surplus of several thousand tons pecan oil is produced annually. The of walnut and almond meats was di- source is the discarded meats from verted to crushing operations. The shelling plants, which are shipped to a following discussion applies to a more central point for processing. The oil is normal situation. obtained by hydraulic pressing. It has Commercial production of almonds been found fairly high in free fatty in the United States is confined to Cali- acids. Some difficulties were experi- fornia. Almonds rank third in acreage enced at first in refining it, but these among the deciduous-tree fruits and have been overcome. The press cake is nuts of California. Prunes and walnuts treated to recover tannin, of which it are ahead of them. Approximately two- contains about 14 percent, and the thirds of our almond crop is shelled. residue is sold for stock feed. Pecan Nearly 10 percent of the meats are oil is suitable as a salad or . moldy, shriveled, or otherwise inedible, The filbert crop, grown principally and contain 40 percent of oil, which in Oregon, is small. Oil-recovery opera- means that about 260 tons of almond tions from any part of it would not be oil could be realized from that source. practicable unless surpluses develop or Only one or two small companies now the industry is faced with the disposal press almond oil; they use mostly of large quantities of damaged or un- edible meats. The oil is low enough in salable meats. Filbert growers foresee fatty acids to be refined to a high- the likelihood of a surplus, as produc- grade salable product by the use of tion is increasing. Like olive oil, filbert bleaching agents alone. It is consumed oil has a high content of combined almost entirely in the cosmetic and . 598 19 5 0-1 1 YEARBOOK OF AGRICULTURE The fruit-flesh oils come only from utilized principally in making soap and avocados and olives. other products that merely require The culture of avocados in the high percentages of oleic acid in the United States is confined to Florida raw materials. The inedible grades, and California, with 83 percent of the which are obtained after the cold- total production in California. Com- pressing, constitute one-third of the mercial plantings are almost entirely total oil present in the olives. The oil in the southern part of the State, par- content of ripe California olives aver- ticularly in the coastal belt from San ages 18 to 25 percent. Between 50 and Diego to Santa Barbara, where the 60 gallons of oil of all grades are usually climate is favorable for this crop. Most obtained from each ton of olives of the crop is sold at prices that make processed. oil recovery from very much of it out Other minor sources of vegetable of the question. The cull portion of the oil, which deserve passing mention crop is usually small, but adverse con- only, include the seeds of watermelon, ditions, such as the heavy freezes of cantaloup, figs, limes, nectarines, pa- 1937 and 1948, sometimes make it payas, i)omegranates, and several dif- larger. ferent berries. Economic extraction The amount of avocados pressed for of the materials will probably not be oil each year is variable, but has not practicable in the foreseeable future, exceeded 100 tons, w^hich would yield because either the processing plants are 10 to 15 tons of oil. The oil, similar to widely separated or the total tonnage olive oil in its high content of combined of the oil represented by the cannery oleic acid, is sold almost exclusively to wastes is relatively small. the cosmetic industry. It commands a The market value of any minor oil high price. is usually based on that of the common 01i\'e oil occupies a unique position bulk oil it most closely resembles, but among vegetable oils in that it is valued the law of supply and demand also may for its distinctive odor and flavor, as affect it. Thus, apricot-pit oil, which well as for its low solidifying point and closely resembles sweet-almond oil and adaptability to many cosmetic and is rci^overed only in limited quantities, pharmaceutical formulations. Califor- is sold at a premium. Sometimes an oil nia accounts for almost all of our pro- will have a "name value" in certain in- duction of olives and in prewar years dustries, in addition to desirable physi- furnished 5 to 10 percent of our na- cal properties. is a case in tional requirement!^ of olive oil. The point. Should an oil be found to have a remainder was imported. War de- high content of a valuable constituent, mands imposed a severe strain on the such as vitamin A or D, or perhaps California olive crop and prices rose to show great resistance to rancidification, unprecedented heights. With the re- its market value may rise appreciably. turn of imports in the postwar years, Otherwise, processors must recognize production of ou declined untü in 1950 that minor oils have no unusual merit it was at about prewar levels. The and must compete on an even basis amount pressed fluctuates widely from with the better-known oils of com- year to year, but it is usually within the merce. range of 2,000 to 3,000 toris in normal times. During the war, production of ERNEST B. KESTER has been en- edible grades amounted to more than gaged ill research on jais and oils at the 5,000 tons. Western Regional Research Labora- In considering olive oil, one must tory since 1939, and is now in charge distinguish betw^een the cold-pressed of the rice-utilization section. He holds (virgin) grade and the hot-pressed or advanced degrees from the Univer- extracted grades. The latter are the in- sity of Minnesota and Northwestern edible grades of commerce and arc University.