Nutritive Value of Navy Beans (phaseolus Vulgaris).

It has been known since 1920 (Johns & Finks, 1920) that the navy bean is an inferior source of protein for rats. Everson & Heckert (1944) reported that raw navy beans were injurious to rats when given at a 10% protein level. They also reported that autoclaving the beans destroyed the injurious effect. Kakade & Evans (1963a, b) confirmed this report and observed that rats given 10% protein as raw navy beans in an otherwise nutritionally complete diet lost weight and died during the experiment. The beneficial and adverse effects of heat on legume proteins have been reviewed by Liener (1958). The beneficial effect of heat on most legumes has been generally attributed to the destruction of antinutritional factors such as trypsin inhibitor and haemagglutinin present in them. Bowman (1944) and Rigas & Osgood (1955) have shown the presence of a partially heat-labile trypsin inhibitor and a haemagglutinin respectively in navy beans. One purpose of the experiment now described was to determine by indirect means the importance of these 'toxic' factors in the low nutritive value of navy beans. Recently, Bandemer & Evans (1963) compared the amino acid composition of navy beans with that of a provisional amino acid pattern (FAO, 1957) and reported that the sulphur-containing amino acids are the most limiting amino acids of navy beans. A study was therefore conducted to see if the observed growth inhibition of rats fed on navy beans is a result of amino acid deficiency or of amino acid imbalance.