Diet alters the fatty acid composition of individual phospholipid classes in beef muscle.

The objective of this study was to investigate the effect of diet on the distribution of phospholipid classes and fatty acid profiles of individual phospholipid classes in longissimus muscle of beef. An experiment was established to examine the effect of pasture-based versus concentrate diet offered to two different breeds (German Holstein and German Simmental bulls) to enhance the content of beneficial fatty acids in beef and improve the meat quality for the consumer. High-performance thin-layer chromatography was utilized to separate the phospholipid classes. The fatty acid composition of the individual phospholipid classes was determined by gas chromatography. The main phospholipid classes in the muscle were phosphatidylethanolamine and phosphatidylcholine, representing approximately 60% of the total phospholipids, followed by phosphatidylinositol ranging between 11.8 and 14.8%. The results have shown that the fatty acid profiles in the detected seven phospholipid classes can be affected by different feeding systems. Pasture-based feeding resulted in an enrichment of total and individual n-3 fatty acids in all phospholipid classes of muscle lipids of bulls compared with those fed on concentrate. In contrast, pasture-based diet significantly decreased the proportion of total and individual n-6 fatty acids in phospholipid classes, except in the sphingomyelin fraction. The total saturated fatty acid proportions in the phospholipid classes were different and ranged between 4.5% in the cardiolipin fraction and 50.5% in the sphingomyelin fraction of muscle lipids of bulls. Furthermore, the diet effects on the saturated fatty acid proportion in the different phospholipid classes differ widely. The results have shown that the C18:1 trans and CLA profiles in the detected seven phospholipid classes can be affected by different feeding systems.