Triglyceride-based composites

Epoxidized plant oils such as castor oil can also be converted into polyols and copolymerized with isocyanates such as toluenediisocyanate (TDI) or methylene-4,49-diphenyldiisocyanate (MDI) to obtain PUs. Meier et al. [56] reported that canola, corn, soybean, and sunflower oil-derived polyols yield PU resins of similar cross-linking densities (and, consequently, similar glass transition temperatures) and mechanical properties, despite differences in fatty acid distribution. 

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Khot, S.N., Lascala, J.J., Can, E. etal. (2001) Development and appUcation of triglyceride-based polymers and composites. Journal of Applied Polymer Science, 82(3), 703-723. 

Khot SN, Lascala JJ, Can E, Morye SS, Williams GI, Pahnese GR, Kusefoglu SH, Wool RP. Development and application of triglyceride-based polymers and composites. J Appl Polym Sci 2001 82 703-723. 

Lipoproteins. A lipoprotein is an endogenous macromolecule consisting of an inner apolar core of cholesteryl esters and triglycerides surrounded by a monolayer of phospholipid embedded with cholesterol and apoproteins. The functions of lipoproteins are to transport lipids and to mediate lipid metabolism. There are four main types of lipoproteins (classified based on their flotation rates in salt solutions) chylomicrons, very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). These differ in size, molecular weight, and density and have different lipid, protein, and apoprotein compositions (Table 11). The apoproteins are important determinants in the metabolism of lipoproteins—they serve as ligands for lipoprotein receptors and as mediators in lipoproteins interconversion by enzymes. 

Table 4 Triglyceride Composition Based on HPLC Analysis During Low-Temperature Storage (wt%)...

The chylomicron remnant particles themselves, derived from lipolysis of the larger chylomicrons (cf. above), contain the residual triglyceride and all of the cholesterol and cholesterol ester from the original chylomicrons. This lipid composition of the chylomicron remnant particles is similar to the above-described lipid composition of both LDL particles (cf. Section 14.1) and LCM (cf. Section 12.1). Based upon this molecular similarity, it appears reasonable to expect that injected LCM could also readily bind apo E (i.e., as an alternative to apo B) in the bloodstream. In this case, the proposed LCM binding of apo E should influence the subsequent biodistribution of those LCM via two endocytic pathways specifically, one pathway mediated by the LDL receptor (a.k.a. apo B,E receptor ) (cf. Section 14.1) and the other pathway mediated by the LRP, since both receptor types have a high affinity for apo E (cf. above). 

A remarkable feature of lipids, either vegetal or animal, is that they share the same fatty acids in triglycerides in the range C12-C20 (Table 14.3). However, there are significant differences in composition. Thus, soybean, sunflower and rapeseed oils are all based on C18 acids, the first two being richer in unsaturated linoleic acid, which could introduce a problem of stability with respect to oxidation. The palm oil has an important amount of C16 acid. Coconut oil is given as an example of Cl2-04 rich oil. As in palm oil the composition of tallow spreads over Cl6-08 acids. 

The official European Community (EC) method for determination of the purity of milk fat is based on triglyceride composition as determined by GC on a packed column (EC, 1999). This is based on a formula for the composition of genuine milk fat of the type 100 = 14.197 C40 — 36.396 C42 + 32.364 C44 — e. The limit of detection varies with the adulterant fat, but is usually <5% foreign fat. A standard reference material (CRM 519) is available (Precht el al., 1998) which has been fully characterized and the triglyceride composition determined collaboratively. Other methods of analysis of the triglyceride data have been evaluated (Collomb et al., 1998a,b Lipp, 1996a,b Ulberth, 1995). 

The complexity of chocolate manufacture arises from the polymorphic nature of its constituent fats, which can come in at least five crystal forms, each with an individual melting point. Cocoa butter is chemically a multicomponent mixture of triglycerides and trace compounds (Davis and Dimick 1986). Approximately 85% of the composition consists of just three triglycerides POP ( 20%), POS ( 40%) and SOS ( 25%), where palmitic (P), oleic (O) and stearic (S) are the fatty acids attached to the glycerol base. The precise composition depends on factors such as growing conditions and therefore can vary between batches, especially from different geographic regions (Chaiseri and Dimick 1989). 

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