Influence of various dry bean fractions, c.v. Carioca 80, on diet efficiency and dietary protein utilization

Raw beans, c.v. Carioca 80, were fractionated into tegument (FR0), dialyzable solids (FR1), water-soluble (FR3) and salt-soluble (FR2, FR5) protein-rich fractions, and the insoluble residue (FR4). Each of these fractions was used at a level of 8% (w/w) in the preparation of balanced diets for rats with casein as the primary source of protein. The protein contributed by each fraction substituted an equivalent amount of casein to maintain total dietary protein at 10%. Tryptophan and sulfur amino acids were supplemented to the levels of these amino acids in a 10% casein diet. The bean fractions decreased rat growth, diet efficiency ratio, protein digestibility and utilization. Autoclaving the bean fractions (121 degrees C, 30 min) prior to being mixed in the diets did improve growth. protein digestibility and utilization, but the values encountered were still significantly lower than those determined for the 10% casein diet. The differences between the casein and the mixed casein-bean protein diets could not be explained on the basis of amino acid scores.