[Evaluation of the protein quality of legume flours obtained by roasting in heated beds]

Roasted flours from cowpea, canavalia and washed lupin were prepared by a thermic treatment in fluid sand beds at 150, 200 and 250 degrees C for 2.0 and 2.5 minutes, followed by dehulling and grinding. A flour produced by pressure cooking at 121 degrees C for 30 min followed by drying was used as reference. The flours were evaluated through residual levels of antitryptic activity, tannin content, available lysine, NPR and protein digestibility. The roasting and the pressure cooking processes increased NPR values. Nevertheless, the NPR values of all legume flours were significantly lower than the NPR casein values. The roasting process carried out under the conditions indicated inactivated trypsin inhibitor activity significantly. A small decrease in tannin content was also observed, with small insignificant changes in available lysine. The protein digestibility of all products was high with lupin, digestibility being equal to that observed for casein. The roasting process in a fluid granular bed allows the production of products of acceptable protein quality with low levels of antiphysiological factors.