[Effects of processing by granular heated beds on the chemical and functional properties of legume grains]

The present research compares the effect of cooking cowpea, canavalia and lupine by pressure cooking and by a granular bed roaster, on chemical and physical characteristics. The wet cooking process was carried out by pressure cooking at 121 degrees C for 30 min at 15 psi, using a bean-to-water ratio of 3 to 1. The cooked samples were dried with heated air (60 degrees C). The granular bed roasting was carried out at 200 and 250 degrees C for contact times of 2 and 2.5 minutes, at a 5 to 1 sand:bean ratio. For this process, a granular bed roaster was designed and constructed. This process induced in the grain temperatures which varied from 90-128 degrees C, and thermic efficiencies which fluctuated between 38 and 60%. The wet and the dry processes did not affect protein and fat content, although available lysine values decreased slightly. The two processes did not affect water absorption and water solubility. The nitrogen solubility index, however, decreased as roasting temperatures increased in the case of the granular bed roaster, and it also decreased in the wet-cooking procedure. Both processes affected color of the cooked flours, with a light orange color, suggesting non-enzymatic browning due to the high temperatures used.