Mono-acid TAG

By now, we have discussed the polymorphism of mono-acid and mixed-acid TAGs. To summarize. Table 6 shows the number and types of polymorphic forms of principal TAGs. 

Figure 2 illustrates diversity in the fatty acid types and compositions of the TAG. The mono-acid and mixed-acid TAG are defined, respectively, on whether the fatty acid chains are of the same fatty acid molecules or not. Even for the monoacid TAG, the diversity maintains in chainlength and parity (odd or even numbers of carbon atoms) of the fatty acids, the number and position of the double bond and the conformation of the double bond, cis or trans, etc. As for the mixed-acid TAG, polymorphic diversity is superimposed over that of the mono-acid TAG in the form of sn (stereo-specific numbered) position. 

Fatty acids are not randomly distributed in the three positions of the TAG in oils and fats. In vegetable oils the saturated and long-chain mono fatty acids have a tendency to occupy the 1 and 3 positions. This is favorable for the formation of P stable TAGs PEP or PEE (also a stable P TAG) upon hydrogenation. Lard is an exceptional fat in that most of the palmitic acid is located in the 2-position. This makes lard a fat that crystallizes in the P form [17]. 

Very recently, the phase behaviors of the other types of saturated mono-acid binary mixtures TAGs, LLL (trilauroyl-glycerol)/(trimyristoyl-glycerol), LLL/PPP, and LLL/SSS, were examined by a SAXSAVAXS simultaneous measurement of SR-XRD (86). 

The egg contains lipids on a large scale, even in its outer region. The shell contains 0.045% lipids in the cuticula and 1.35% lipids in the shell membrane (Suyama et al., 1977). Neutral and polar lipids occur in proportions of 5 1 and 6 1, respectively. Neutral lipids consist of mono-, di-, and triacylglycerols (TAG), cholesterol and cholesteryl esters, and free fatty acids (EA). The main components in the neutral lipid fraction of the shell and its adjoining layers are cholesterol and cholesteryl esters, in addition to diacylglycerols the TAG content is low. 

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