Protein quality and acceptability of animal and soybean products

Three studies were conducted to investigate the effects of animal and soybean products on protein quality, lipid status, and acceptability. In study A, 98 Sprague-Dawley strain, weanling rats were divided into 13 groups of seven to eight animals each and fed four different sources of protein (pork, lactalbumin, soy processed to resemble meat, and tuna fish) for incorporation into rations to contain 8, 10, or 12% protein on the basis of amino acid proportionality patterns. Regression slopes for carcass fat and total body weight gain were similar, but some differences in the slopes for carcass protein were found, with lactalbumin giving the highest rate of response. Similar values for final body weight, cooked weight without tails, total body weight gain, carcass ash, ratio of total carcass protein to total protein consumed, nitrogen utilization, and relative nitrogen utilization were found for pork and tuna. Additionally, carcass nitrogen, carcass protein, feed efficiency ratio (FER), protein efficiency ratio (PER), adjusted protein efficiency ratio (APER), and relative protein efficiency ratio (RPER) for pork, soybean, and tuna produced similar results. Lactalbumin feeding produced less carcass fat and percentage of fat, while pork, soybean, and tuna gave similar values of carcass fat and percentage of fat. In study B, 13 human adults were fed five laboratory controlled diets containing pork, beef, fish, soy-analogues, and poultry proteins. Mean nitrogen balances of subjects fed fish and poultry proteins were significantly higher than those of the 3 other proteins (pork, beef, and soybean). Fish and poultry diets had significantly higher apparent nitrogen digestibilities and retentions than did pork, beef, and soybean diets. Mean fat balances were shown to be considerably greater in pork and beef periods as compared to fish, soybean, and poultry periods. The basic changes for blood serum LDL-cholesterol and total cholesterol were markedly higher for pork and beef diets than were those for fish, soybean, and poultry diets. Thus, even when fish and poultry diets were fed to supply 20% more protein than did pork and beef diets, they still supplied 10% less fat and produced more favorable blood serum lipid patterns. In study C, taste/odor acceptability of chocolate cow\u27s milk and chocolate flavored soy milk were compared. Based on the taste, a majority of the panelists favored chocolate cow\u27s milk to chocolate soy milk