Some of the Minor Oil importations. As recoverable oils 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 fats, 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, castor oil 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. iodine value. 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, safflower, 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—almond, wal- ings. Those with low iodine values nut, pecan, 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 almonds" 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 olive oil. 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-seed oil, 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 vegetable oil. 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.