Effect of heat treatment of legumes on available lysine

The newer dye‐binding capacity difference method of measuring available lysine in legumes was shown to agree extremely well with the established but laborious fluorodinitrobenzene method. This was true both with raw legumes and with heated samples in which there had been a considerable reduction in the amount of available lysine present. Nine samples of commercially obtained dried legumes were cooked for 1, 2 and 8 h at atmospheric pressure and for 30 min under 15 lb pressure. Losses of available lysine varied with the length and severity of heat treatment and with the type of legume. The variation with the type of legume appears to be due to the amount of reducing sugars in the legumes since both reducing sugars and available lysine fell during heat treatment, and the amount of lysine lost appears to be linked with the amount of reducing sugars initially present or added as glucose.