Polyunsaturated glycerides

Sulfated Natural Oils and Fats. Sulfated natural triglycerides were the first nonsoap commercial surfactants introduced in the middle of the nineteenth century. Since then sulfates of many vegetable, animal, and fish oils have been investigated (see also Fats AND FATTY oils). With its hydroxyl group and a double bond, ricinoleic acid (12-hydroxy-9,10-octadecenoic acid) is an oil constituent particularly suited for sulfation. Its sulfate is known as turkey-red oil. Oleic acid is also suited for sulfation. Esters of these acids can be sulfated with a minimum of hydrolysis of the glyceride group. Polyunsaturated acids, with several double bonds, lead to dark-colored sulfation products. The reaction with sulfuric acid proceeds through either the hydroxyl or the double bond. The sulfuric acid half ester thus formed is neutralized with caustic soda ... 

The polyunsaturated aliphatic monocarboxyhc acids having industrial significance include sorbic, linoleic, linolenic, eleostearic, and various polyunsaturated fish acids (Table 3). Of these, only sorbic acid (qv) is made synthetically. The other acids, except those from tall oil, occur naturally as glycerides and are used mosdy in this form. 

LINOLENIC ACID, CAS 463-40-11. Also called 9.12,15-ocladecatri-enoie acid, formula CH,CH CH CHCH2CH rHrH CH CH(CH bCOOH. This is a polyunsaturated fatty ucid (three double bondsl, It occurs as the glyceride in many seetl tats. It ts an essential laity acid in the diet. See also Vegetable Oils (Edible). At room temperature, linolenic aeid is a colorless liquid soluble in most organic solvents insoluble in water. Specific gravity (1.916 (2(1/4"C mp -ll C bp 23()"C. Combustible. Linolenic acid finds use in various pharmaceuticals and drying oils. 

More importantly, lipid peroxidation can be controlled or minimized by design of formulation. While saturated lipids (e.g., MCTs) will themselves not be susceptible to peroxidation, they may contain sufLcient unsaturated impuritiesto be problematic. Similarly, monounsaturated lipids (e.g., oleic acid glycerides) are much less susceptible to peroxidation. The relative rates of peroxidation of oleic, linoleic, and linolenic acids are 6 64 100, respectively (Swern, 1995). Monounsaturated lipids may, however, may contain polyunsaturated impurities, which will catalyze the oxidation ofthe monounsaturated components (Swern, 1995). Surfactants, particularly those based on PEG, may contain peroxides that can promote lipid peroxidation thus, particular attention should be paid to the purity and source of all formulation components. 

Soybean oil contains 1.5-3.0% phospholipids (71). Crude soybean lecithin has an oil content of about 30%. PC is present at a level of about 16%., PE about 14%, and inositol phospholipids about 12% (7). As can be seen in Table 18 (8), the fatty acid compositions of soybean phospholipids are rich in polyunsaturated fatty acids. Miscellaneous low-level constituents include water, phosphatidic acid, pigments, galactosyl glycerides, various glycolipids, phosphatidylserine, carbohydrates, sterols, and tocopherols. Phosphorus content of crude soybean oil extracted from flours can vary depending on extraction temperature and flour moisture (72). 

On hydrolysis, fi oils yield a mixture of fatty acids derived mainly from mixed glycerides. Separation of these fatty acids based on molecular wei t or degree of unsaturation is oonoplicated by several factors. First, the relatively small differences in their molecular wei ts make it difficult to separate them by conventional means, particularly v en saturated and xmsaturated fatty acids of the same chain length are to be sqparated. Second, polyunsaturated corpouncls are readily susceptible to polymerization, degradation and/or oxidation, even at moderately elevated tenperatures. 

As far as fatty acids go, there is no basic difference between the different types of olive oils there are large amounts of monounsaturated and polyunsaturated fatty acids ( 70 % oleic acid and 10 % hnoleic acid, —> 2.13). The fatly acids are mostly bound in mono-, di- and triglycerides in ohve oil, the relative amoimt of glycerides... 

Thermal oxidation of unsaturated fats is accompanied by considerable isomerization of double bonds, leading to products containing trans double bonds and conjugated double bond systems. Non-volatile decomposition products are formed by thermal oxidation, hydrolysis and cyclization. A large number of hydroxy, alkoxy-substituted, epoxy and keto compounds are produced by oxidation, free fatty acids and mono- and diacylglycerols by hydrolysis, and cyclic monomers by cyclization of polyunsaturated fatty acids in heated fats. Aldehydo glycerides (also referred to as core aldehydes ) and keto glycerides... 

Free fatty acids occur only in small amounts in biological materials. They can be recovered from ether or petroleum ether extracts by extraction with diluted aqueous or alcoholic alkaline solutions as the corresponding alkaline salts and reconverted to free acids by treatment with acids. The use of diluted alkaline solutions prevents hydrolytic cleavage of glycerides and glycerophospholipids. Free fatty acids may also be isolated by adsorption to basic ion exchange resins (Carlson and Wadstrom 1958, Hornstein et al. 1960). Because of a tendency of polyunsaturated fatty acids to isomerization Biegler et al. (1960) recommend the use of weak basic adsorbents. After isolation free fatty acids are assayed by titration. 

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