Increasing desirable polyunsaturated fatty acid concentrations in fresh beef intramuscular fat

© 2017 CAB International.Beef is an excellent source of protein, B vitamins and trace minerals and can be an important source of long chain n-3 polyunsaturated (PUFA) and other bioactive fatty acids such as vaccenic acid (VA) and conjugated linoleic acid (CLA). However, beef consumption has been declining mainly due to concerns over its saturated fat content. Despite generalizations about beef fat, fatty acid analyses of retail beef suggests that lean beef falls within dietary recommendations for fat intake (total and saturated), can be a rich source of heart healthy cis-monounsaturated fatty acids and has a low n6-/n3-PUFA ratio. Since the 1970s, numerous attempts have been made to increase the PUFA content of beef, particularly n-3 PUFA and to further increase the content of VA and CLA. This has been mainly done by feeding cattle PUFA rich sources such as fresh forage (pasture), conserved forage, oil seeds, plant or marine oils or their combinations. The main challenge when trying to enrich beef with PUFA has been their extensive biohydrogenation in the rumen resulting in limited deposition compared with monogastrics (e.g. pigs and chickens). To address this, several techniques to protect PUFA against ruminal biohydrogenation or to reduce the extent of biohydrogenation have been investigated including different methods of feed processing, encapsulation of oil inside a microbial resistant protein matrix (e.g. formaldehyde-treated protein), chemical modification of fatty acids (calcium salts or amides) or protection using plant secondary metabolites and enzymes. The present review examines the fatty acid composition of retail beef in relation to human health and evaluates the effectiveness of different feeding strategies and possibilities for future improvement in the content of healthful fatty acids in beef, specifically vaccenic, rumenic and omega-3 fatty acids.