Vegetable oils are also obtained from certain field and tree crops. The field crops include soybeans, sunflowers, peanuts, rapeseed, safflower, sesame, cotton,, corn, and flax. The most important tree crops are coconuts, palm, palm kernel, olives, castor and tung. All those tree can produce oil is treat with certain kind of treatment, every kind of fruit may need different process to produce oil.
The seven major vegetable oils, soybean, peanut, sunflower, coconut, palm, rapeseed, and cottonseed, are used primarily in food products. In the United States, salad and cooking oils, shrotening and margarine comprise a major share of the food fat market, soybean oil as the primarily vegetable oil used for these products.
Demand in the food fat market has shifted from solid fats to liquid oil and from animal fats to vegetable oils, stimulating technological development in the processing of vegetable oils to yield stable products. Soybean oil requires special processing because of its unstable linolenic-acid component. Palm oil, which in a highly saturated oil, is used mainly for shortening, however, technological improvement in the fractionation of palm oil yield liquid oil similar to peanut or oilve, linsead and castor have no food uses because of their toxic properties. Industrial vegetable oils are used in paints and varnishes, other drying oil products, fatty acids, feeds, resins, and plastics.
specialty vegetable oils include those obtained from nuts, particularly walnuts, from such herb seed crops as sesame, and from plants whose commercial possibilities are being explored for the first time, such as the North American desert plant, Cuba.
The type of consumed in various feed oils has become a major issue, spurred by concern about high cholesterol levels leading to heart diseases. Saturated fats, those containing large numbers of hydrogen atoms. In their chemical composition, are suspected of raising cholesterol levels. "Tropical" vegetable oils, palm kernel, palm and coconut particularly are high in saturated fats, soybean, corn, olive, cottonseed, and most other vegetable oils contain large amounts of polyunsaturated oils, which are considered physiologically less threatening.