Triacylglycerols fats and oils

Triacylglycerols (fats and oils) store the majority of the energy in most animals and plants. Fats such as beef tallow remain solid or semisolid at room temperature while oils such as olive oil or corn oil are liquid at that temperature. Oils solidify only at lower temperatures—in a refrigerator, for example. The different kinds of fatty acids found in the side chains of the triacylglycerol cause the different melting temperatures. The fatty acids of oils contain more double bonds than do those of fats. 

The structures of lipids are quite varied triacylglycerols (fats and oils), waxes, phospholipids, sphingolipids, steroids, eicosanoids, fat soluble vitamins, and pigments. Some lipids are simple in structure while others are more complex. Among these molecules are those which are esters in nature and therefore saponifiable in aqueous base. Others are nonsaponifiable. Many are completely nonpolar while others are amphipathic, that is, they have a polar/nonpolar nature. 

Lipid (Section 23.1) A substance of biological origin that is soluble in nonpolar solvents. Lipids include fatty acids, triacylglycerols (fats and oils), steroids, prostaglandins, terpenes and terpenoids,... 

Glycerol A trihydric alcohol to which three fatty acid molecules are estetiGed in the formation of triacylglycerols (fats and oils). Glycerol has a sweet taste and is hygroscopic (attracts water) it is commonly used as a humectant in food processing. 

The chemical reactions of the triacylglycerols (fats and oils) are similar to the hydrogenation of aUcenes and the hydrolysis and saponification of esters. The double bonds in unsaturated fatty acids of a triacylglycerol will react with hydrogen to produce saturated (single bonds) fatty acids. 

Fats and oils are naturally occurring mixtures of triacylglycerols also called triglyc erides They differ m that fats are solids at room temperature and oils are liquids We generally ignore this distinction and refer to both groups as fats... 

S. N. Dudd, M. Regert and R. P. Evershed, Assessing microbial contributions to absorbed acyl lipids during laboratory degradations of fats and oils and pure triacylglycerols absorbed in ceramic potsherds. Organic Geochemistry, 29, 1345 1354 (1998). 

Triacylglycerols, commonly refered to as fats and oils, consist of three fatty acids linked to a molecule of glycerol, a three-carbon alcohol. Fatty acids are long-carbon-chain molecules, each with a single carboxyl functional group. Common examples are stearic acid and palmitic acid, shown in Figure 16.3. 

This unit describes the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic method (AOCS, 1999a AOAC International, 2000), a novel method for measuring the total amount of fat with isolated trans double bonds. It is applicable to natural fats (ruminant fats) and processed fats and oils (partially hydrogenated fats and oils or refined vegetable oils) consisting of long-chain fatty acid methyl esters or triacylglycerols with trans levels >5%, as percent of total fat (AOAC International, 2000). 

Complex mixtures of acylglycerols are the major components of naturally occuring fats and oils. Oils are fats that are liquid at room temperature. Their liquidity is attributed to their acid residues having a high proportion of C = C bonds. Triacylglycerols are the predominant energy store in animals and are mainly located in adipose tissue. 

Fats and oils are triacylglycerols with different physical properties. 

In Section 10.6 we learned that fats and oils are triacylglycerols that differ in the number of degrees of unsaturation in their long alkyl side chains. 

Fats and oils are triacylglycerols that is, they are triesters of glycerol and these fatty acids. 

Unlike many fats and oils, the cocoa butter used to make chocolate is remarkably uniform in composition. All triacylglycerols contain oleic acid esterified to the 2° OH group of glycerol, and either palmitic acid or stearic acid esterified to the 1 ° OH groups. Draw the structures of two possible triacylglycerols that compose cocoa butter. 

Most of the flavor compounds in fats and oils are produced by the reaction of oxygen with unsaturated fatty acids in triacylglycerols or polar lipids. On the other hand, some flavor compounds such as those present in cocoa butter, roasted sesame oil, or roasted peanut oil are generated by the interaction of reducing sugars with amino compounds during thermal processing. 

Fats and oils contain various classes of compounds (16). These componds are primarily neutral lipids that include triacylglycerols (triglycerides) with lower amounts of diacylglycerols (diglycerides), monoacylglycerols (monoglycerides),... 

---