Total lysine and available lysine were used for predicting the damage
to lysine in soya protein heated with glucose and in alkali. The amoun
ts of both types of lysine decreased during the treatments. The conten
t of total lysine was much higher than that of available lysine. In so
ya protein heated with glucose, the available lysine content decreased
by 78-85 % and that of total lysine by 17-40 %. In soya protein heate
d in alkali, available lysine decreased by 7-24 % and total lysine by
7-13 %. Since available lysine was more sensitive, changes in total ly
sine underestimated the nutritional damage.