No abstract

Conjugated fatty acids (CFAs) are a group of positional and geometric isomers of polyunsaturated fatty acids (PUFAs) with conjugated double bonds. There are several subgroups of CFAs including conjugated linoleic acids (CLAs), conjugated linolenic acids (CLNAs), conjugated eicosapentaenoic acids (CEPAs), and conjugated docosahexaenoic acids (CDHAs). CFAs, especially CLAs, have been studied in recent years both for their health benefits and factors that affect their level in muscle food products. CFAs have been reported in numerous studies as having antitumor, antiobesity, antidiabetes, anticardiovascular disease, and modulating immune system effects. These biological activies are involved in changes of lipid peroxidation and energy expenditure, as well as inhibitory effects on the hormone receptor, lipid metabolism, lipoprotein lipase activity, and adiponectin production. A large body of studies has revealed that the diet, processing, storage conditions, slaughter season, and age are common factors that affect CFA content in muscle food products, as detailed in this review. Recommendations are made regarding animal farming and meat product processing to obtain high CFA content meat products and to optimize the benefits of CFA for health promotion.

Response surface methodology (RSM) was used to optimize the degree of esterification of p-coumaric acid to triolein via lipase-catalyzed acidolysis, and enzyme load, reaction time and mole ratio of substrates were selected as variables in the experimental design. The results showed that the model employed was highly sufficient for determining the effectiveness and interaction of three selected variables, enzyme load, reaction time and the mole ratio of substrates, on the dependent variable, the degree of esterification. Although the optimization point was not found in the selected range of the three variables, the steepest ascent analysis suggested that an increase of these three variables might lead to a stationary point. However, based on the limitations on increasing the range of tested variables, including possible oxidation of synthesized lipids and increased cost, the degree of esterification so yielded in the designed central composite design should be the one closest to the possible ideal optimized degree. The p-coumarates so produced exhibited varying antioxidant performance in the tested muscle food model, which could be explained by their different lipophilicity. Moreover, the potential health benefits of synthesized phenolic lipids have been discussed. Graphical Abstract