Abstract
Objectives
Beef is a rich source of branched chain fatty acids (BCFA) in the American diet. Once consumed, utilization of fatty acids depends on their lipid class in foods.
Our objective is to characterize the distribution of BCFA among lipid classes in commercial ribeye steaks, specifically sampled from grass-fed, angus, and prime beef.
Methods
Beef was obtained from a supermarket in Austin, Texas. Samples were cut into pieces (1 mm3) and extracted by the method of Bligh and Dyer. Extracts were fractionated into triacylglycerol (TAG), phospholipids (PL), cholesterol esters (CE), and free fatty acids (FFA) by thin layer chromatography (TLC). PL were further fractionated into phosphatidylcholine (PC), lyso-PC, phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and sphingomyelin (SM). Fatty acid methyl esters (FAME) were prepared from each fraction by treatment with BF3/methanol and analyzed by high resolution capillary gas chromatography (GC) with positive structure identification by MS/MS of the molecular ion.
Results
Total BCFA in PL of grass-fed beef is the highest (1.25 ± 0.05%, w/w; mean ± SD) compared with those in PL of other beef. Total BCFA in TAG (1.30 ± 0.37%, w/w) were not different between angus and prime beef. BCFA were detected in all lipid fractions. Anteiso-15:0, anteiso-17:0, iso-15:0, iso-16:0, iso17:0, iso-18:0 were detected in most fractions.
Conclusions
Total BCFA in PL of grass-fed beef is the highest (1.25 ± 0.05%, w/w; mean ± SD) compared with those in PL of other beef. Total BCFA in TAG (1.30 ± 0.37%, w/w) were not different between angus and prime beef. BCFA were detected in all lipid fractions. Anteiso-15:0, anteiso-17:0, iso-15:0, iso-16:0, iso17:0, iso-18:0 were detected in most fractions.
Funding Sources
This study was supported by the National Cattleman's Beef Association and the North Dakota Beef Commission.