Acids common, obtained from fats, 439 Table

Table 15.1 Common Acids Obtained from Fats ...

A carboxylic acid contains a carboxyl group, which is a hydroxyl group attached to a carbonyl group. Many carboxylic acids have common names, which are derived from their natural sources. Formic acid is injected under the skin from bee or red ant slings and other insect bites. Acetic acid is produced when ethanol in wines and apple cider reacts with the oxygen in the air. Propionic acid is obtained from the fats in dairy products. Butyric acid gives the foul odor to rancid butter (see Table 14.2). 

Most naturally occurring fats and oils are mixtures of triglycerides containing a variety of saturated and unsaturated fatty acids. Even the individual triglycerides are often mixed, containing two or three different fatty acids. In general, oils from plants and cold-blooded animals contain more unsaturations than fats from warm-blooded animals. Table 25-2 gives the approximate composition of the fatty acids obtained from hydrolysis of some common fats and oils. 

Polyunsaturated and oxygenated fatty acids, obtained from triacylglycerols (TAG) of several different plant and animal species, are valuable materials feedstock for value-added products in a variety of industries food, pharmaceutical, cosmetics, and paints and coatings. The acyl species, their chemical structure, and their most abundant sources are summarized in Table 1. In contrast to inexpensive Cie and Cig saturated and A9-unsaturated acyl groups, such as palmitic (16 0), stearic (18 0), oleic (18 l-9c), linoleic (18 2-9c, 12c), and a-linolenic acid (ALA 18 3-9c, 12c,15c), recovered from the oil of soybean and other common sources, and C4-C16 saturates from palm oil and milk fat, polyunsaturated and oxygenated acids are derived from less common sources, and particularly for polyunsaturated fatty acid (PUFA), are typically present at only 20 0% purity. 

The composition of common fats and oils are found in Table 1. The most predominant feedstocks for the manufacture of fatty acids are tallow and grease, coconut oil, palm oil, palm kernel oil, soybean oil, rapeseed oil, and cottonseed oil. Another large source of fatty acids comes from the distillation of cmde tall oil obtained as a by-product from the Kraft pulping process (see Tall oil Carboxylic acids, fatty acids from tall oil). 

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