Write a notes from an imaginary passage on animal and vegetable oils
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VEGETABLE OILS AND FATS. Oil extraction by traditional methods often requires various preliminary operations, such as cracking, shelling, dehulling, etc., after which the crop is ground to a paste. The paste, or the whole fruit, is then boiled with water and stirred until the oil separates and can be collected. Such traditional methods have a low rate of efficiency, particularly when performed manually. Oil extracted by pressing without heating is the purest method and often produces an edible product without refining.
Modern methods of oil recovery include crushing and pressing, as well as dissolving the crop in a solvent, most commonly hexane. Extracting oil with a solvent is a more efficient method than pressing. The residue left after the removal of oil (oilcake or meal) is used as feedstuff.
Crude vegetable oils are obtained without further processing other than degumming or filtering. To make them suitable for human consumption, most edible vegetable oils are refined to remove impurities and toxic substances, a process which involves bleaching, deodorization and cooling (to make the oils stable in cold temperatures). The loss involved in these processes ranges from 4 to 8 percent. The FAO concept includes raw, refined and fractioned oils, but not chemically modified oils.
With some exceptions, and in contrast to animal fats, vegetable oils contain predominantly unsaturated (light, liquid) fatty acids of two kinds: monounsaturated (oleic acid - mainly in extra virgin olive oil) and polyunsaturated (linoleic acid and linolenic acid - in oils extracted from oilseeds).
Vegetable oils have a wide variety of food uses, including salad and cooking oils, as well as in the production of margarine, shortening and compound fat. They also enter into many processed products, such as mayonnaise, mustard, potato chips, French fries, salad dressing, sandwich spread and canned fish.
Industrial and non-food uses of vegetable oils include the production of soaps, detergents, fatty acids, paint, varnish, resin, plastic and lubricants.
ANIMAL OILS AND FATS. This chapter includes animal fats that are obtained in the course of dressing the carcasses of slaughtered animals (slaughter fats), or at a later stage in the butchering process when meat is being prepared for final consumption (butcher fats). Butter and similar products obtained from milk are included in Chapter 18.
Processed animal fats include lard obtained by melting raw pig fat and tallow obtained from raw fat of other animal species. Animal fats are largely used in the production of margarine, shortening and compound fat. They also enter into many processed food products. Industrial and non-food uses of animal fats include the production of soaps, fatty acids, lubricants and feedstuffs.