Research into foods from animal sources. II. Recent developments in beef and dairy products

Abstract

Research on increasing the polyunsaturated fatty acid content of the fat of beef and of milk, and of lamb and other ruminant animals has been stimulated by the discovery that polyunsaturated vegetable oils can be encapsulated or “protected” by a coating of casein treated with formaldehyde. The “protected” oil passes through the rumen of the animal, is digested in the stomachs, and is adsorbed without the hydrogenation that occurs normally in the rumen. Human feeding tests have shown that a diet containing beef, cheese, butter, and milk produced in this way ( P S ratio = 0.89 ) has a marked effect in reducing serum cholesterol and blood plasma lipids and increasing fecal cholesterol. The magnitude of the changes in blood constituents is produced by a controlled diet of P S ratio = 1 obtained by feeding vegetable oils. A court ruling has declared the Filled Milk Act of 1923 unconstitutional, thus opening up the market for filled milk products (containing nonfat milk solids and vegetable oils) in interstate commerce. Thus, the technological basis for increasing the P S ratio of animal products is relatively well established, for high P S ratios in hog and chicken fat had already been attained. Economic, and marketing problems remain. Also, state and local regulations are changing rapidly. The “nutrition community” must be aware of these changes and be in a position to give sound nutritional advice on the laws and regulations which will control the production and distribution of animal products desirable in the prudent diet.