Lean beef: impetus for lipid modifications.

Health-conscious consumers want lean beef. The beef industry has responded by physically removing much of the adipose tissue from retail products and by initiating attempts to produce--genetically and environmentally--cattle with more muscle, less external fat, and less seam fat, without sacrificing the quality dependent on the amount of marbling present. Offering lean beef that is closely or completely trimmed of external fat has improved retail beef sales. Impetus for modification of the lipid composition of bovine muscle and adipose tissue, including marbling, has resulted from the following: (a) diet/health concerns of consumers and demands for leaner beef, (b) research clarifying effects of dietary fatty acids and cholesterol on serum cholesterol levels, (c) dietary guidelines and recommendations from health organizations, and (d) dietary recommendations by physicians and dietitians to reduce beef consumption. Analysis of cholesterol content of marbling dissected from the rib (longissimus dorsi) muscle revealed that marbling contributes little to total cholesterol content. Cholesterol content of marbling was 117 mg/100 gm intramuscular adipose tissue (equivalent to about a 2 mg cholesterol contribution to a 100-gm serving of uncooked meat). The difference in fatty acid composition of lean meat and of adipose tissue is primarily in the percentage of polyunsaturated fatty acids, which is higher in lean meat. The most prevalent fatty acids in adipose tissue including marbling were: palmitic acid (24.1%), stearic acid (13.5%), and oleic acid (37.7%).