Triacylglycerol chemical property

Waxes and Triacylglycerols Chemical Properties of Triacylglycerols Phospholipids Steroids Cholesterol, Bile Salts, and Steroid Hormones Cell Membranes... 

The physical and chemical properties of individual oils and fats are determined by the nature and proportions of fatty acids that enter into the triglycerides composition. Animal and dairy fat like plant oils are dominated by triacylglycerols, with steroids present as minor components, cholesterol and its esters being the most significant. The triacylglycerols of animal fats differ from plant oils since they contain more of the saturated fatty acids and consequently are solid at room temperature. 

The number of double bonds in a fatty ester radical significantly affects both physical and chemical properties of the triacylglycerol. The highly unsaturated (three double bonds) linolenic acid (18 3) is unstable to oxidation, and undesirable odors and flavors can develop. The rate of oxidation 18 3 is 15-fold greater than that of oleic acid (18 1). 

What chemical property do waxes, triacylglycerols, and steroids have in common ... 

The component fatty acids and alcohols of wax esters have an even number of between 10 and 30 carbon atoms. Normally, they are straight chain saturated or monounsaturated chains of 16-24C. Branched and odd numbered chains are rare in both constituents except for the bacterial waxes. Wax esters from cold-water organisms exist as oils down to about 0°C and their physico-chemical properties differ from those of the triacylglycerols in that they are more hydrophobic and less dense, which may help to provide greater buoyancy for marine animals. 

Triacylglycerols are quantitatively the most important class of dietary fats. Their biologic properties are determined by the chemical nature of the constituent fatty acids, in particular, the presence or absence of double bonds, the number and location of the double bonds, and the cis-trans configuration of the unsaturated fatty acids. 

Interesterification involves an exchange of acyl groups within and between triacylglycerol molecules. This re-distribution of the fatty acids results in modification of the physical properties and nutritional properties of the fat (Frede, 1991). The traditional process of interesterification involves the use of chemicals. 

Natural oils and fractionated oils usually have their acyl chains organized in a nonrandom manner, but they become randomized after interesterification with a chemical catalyst. There is no change in fatty acid composition, only in triacylglycerol composition, but this leads to a modification of the physical properties. More selective interesterification can be achieved with enzymic catalysts (Section 8.5). 

There is considerable interest in the chemical composition and properties of citrus oils and essences as well as the role they play in food and nonfood industries. Citrus peel oils and essences possess a pleasant aroma, with oxygenated compounds being the major constituents that account for their characteristic odor. Terpenes, the most abundant components in cold-pressed citms peel oil, are removed in concentrated oil production, usually by use of adsorbant and supercritical carbon dioxide, to increase the concentration of oxygenated compounds and to enhance the qualification of the oil. Meanwhile, citms seed oils are composed largely of triacylglycerols and are rich in oleic and linoleic acids. 

Most of the lipids found in the body fall into the categories of fatty acids and triacylglycerols glycerophospholipids and sphin-golipids eicosanoids cholesterol, bile salts, and steroid hormones and fat-soluble vitamins. These lipids have very diverse chemical structures and functions. However, they are related by a common property their relative insolublity in water. 

---