Fatty acids determine the physical and chemical properties of fats. Animal fats, regardless of species, have more saturated and monounsaturated than polyunsaturated fatty acids. The major fatty acids in meat are palmitic (16:0), stearic (18:0), palmitoleic (16:1), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids, among which oleic acid is the most predominant. Arachidonic acid (20:4 cis 5,8,11,14) is an essential fatty acid only found in animal fats and can be used as a quality control indicator in the fatty acid analysis. Fatty acid analysis has been traditionally performed by gas chromatography (GC) of volatile fatty acid derivatives, prominently the methyl esters, and flame ionization detection (FID), in which the carbon chain of fatty acids is degraded to the formylium ion CHO+. The FID is very sensitive and is the most widely used detection method for GC, providing a linear response, i.e., peak area, over a wide range of concentrations. Researchers have been used the FID peak area to calculate the percentages of fatty acids. However, the FID is a “carbon counter” and relies on the “equal per carbon” rule; therefore, at the same molar concentration, fatty acids with a different number of carbons produce different peak areas. The recent development of mass spectrometry technology has improved the specificity of fatty acid detection. Specific target and qualifier ions provide better identification and more accurate quantification of fatty acid concentrations. Although fatty acids can be identified through comparing ion fragmentation with various databases, authentic standards are needed for quantification purposes. Using mass spectrometry, more than 50 fatty acids have been identified in meat samples. Some branched-chain fatty acids may have flavor, safety, and shelf life implications in meat products.
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