Gunstone Saturated acids

The so-called random distribution hypothesis originally proposed by Hilditch s co-workers has, therefore, been abandoned in favor of several restricted random theories (Gunstone, 1962 Kar-tha, 1953 Lands et al., 1966 Subbaram and Youngs, 1964 Youngs, 1961 Youngs and Subbaram, 1964 Vander Wal, 1960) the 1,3-random-2-random hypothesis of Vanderwal considers that saturated acids are mainly random distributed on the 1- and 3-positions, whereas unsaturated ones are random distributed on the 2-position. Evidence for the validity of this hypothesis has been given by many... 

Table 11.1 Systematic and common names of saturated fatty acids together with the shorthand designation and typical occurrence (compiled from Gunstone et al., 1994 Hilditch and Williams, 1964 Perkins, 1993 Robinson, 1982). The shorthand designation denotes Cx n where x is the number of carbon atoms and n is the number of double bonds.

There follows a brief account of the commodity oils. This includes the nature of the oil and any special features, its production levels, and major areas of production. Most of these oils are discussed in greater detail elsewhere in this series and in Gunstone (1). Triacylglycerol composition is indicated by three-letter symbols that include all of the isomeric triacylglycerols containing the acids designated where P = palmitic, St = stearic, S = saturated, O = oleic, L = linoleic, and Ln = linolenic. 

Gunstone ct found that separation of saturated and unsaturated fatty acid glycerides by crystallization at -10° is improved by addition of silver nitrate in methanol to complex with the unsaturated components. Morris reports separation of CIS and trans fatty acids and oxygenated fatty acids by thin-layer chromatography on silica gel impregnated with silver nitrate. With untreated silica there was no separation. 

Palmitic acid (PA) or n-hexadecanoic acid is the most common saturated fatty acid (SFA) found in plants, animals, and microorganisms (Gunstone et al., 2012). As the name suggests, PA is characteristic of palm oil and its saponified form was discovered and isolated for the first time by Fremy (1840). The major difference between palm oil and other vegetable oils is the higher proportion of PA (Table 1). 

Data are taken from Pretsch et al. (1976) Levy et al. (1980). The latter book also contains many C-NMR data on steroids and other complex lipids. More detailed results for saturated and unsaturated acids and esters are given by Gunstone et al. (1976, 1977), Bus et al. (1976, 1977), Tulloch (1976, 1977) and Johns etal. (1977). 

The quality speeifieations of biodiesel fuel obtained from com oil is changeable as a result of its broader fatty acid distribution since com oil has a wide range of saturated-unsaturated fatty acid contents from region to region as well as time to time (Lofland Quasckenbush 1956 Ericson 1989 Gunstone 2011 Vesna et al., 2013). 

Virgin coconut oil is obtained from the mature kernel of the coconut by mechanical or physical means with or without the application of minimal heat (Dia et al., 2005). Coconut oil contains about 90% saturated fats. The oil contains predominantly triglycerides with 86.5% saturated fatty acids, 5.8% monounsaturated fatty acids and 1.8% polyunsaturated fatty acids (Gunstone 2011 Hui 1996 Marina et al., 2009). 

Pancreatic lipase hydrolysis has proved (Coleman, 1963a Fedeli et al., 1965 Gunstone and Padley, 1965 Mattson and Volpenhein, 1961 Vander Wal, 1960) that acids are not randomly distributed on the three positions of glycerol with very few exceptions, the 2-posi-tion is predominantly occupied by unsaturated acids, whereas the saturated and C20-22 monounsaturated acids are predominantly distributed in the 1,3-positions of glycerol. 

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