ABSTRACTThe effect of temperature, time and moisture content on the loss of nitrogen solubility of heated bean flour and protein isolates was studied. Solubility loss followed first‐order reaction kinetics in almost all cases studied. The rate of solubility loss was greatly increased with increasing moisture content both for flour and protein isolates; protein isolate was far more sensitive to heat treatment than the flour. Activation energies for the first‐order reaction constants were calculated and ranged between 20–30 kcal