The Biological Value of the Protein of Field Pea Products with a Comparison of Several Methods used for This Determination

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Abstract
The protein of raw Alaska field peas is inferior to that of casein when both are fed at the 10% level. Of the pea products studied as sources of protein the germ proved to be slightly but not significantly more efficient, whereas both the sprout and immature pea were significantly lower in value than the raw pea. Supplementation of at least half of the raw pea protein with cereal grains materially improved the biological value presumably because this increased the methionine content. Canning has a very harmful effect on the pea protein probably because the cystine content is lowered by this process. Baking, too, lowers the value significantly. Three methods of determining the biological value of proteins have been compared: protein retention, protein efficiency and a metabolism study. Biological value expressed either as protein efficiency or protein stored per gram eaten resulted in about the same difference (approximately 55%) between the casein or pea protein. The biological value of casein at a 10% level determined in a metabolism study proved to be 65.6%, that for peas, 57.3%, a difference of 8%. The coefficients of true digestibility for casein and peas from this study were 98.6% and 91.6%, respectively, a difference of 7%. A comparison of 2 groups of animals (pair and ad libitum fed) on a 10% casein diet showed a significant difference in weight gains but not in protein efficiency or protein stored per gram of protein eaten.