Feeding trials have been done with rats to assess the effects of long-term (700 d) consumption of diets based on raw cowpeas (Vigna unguiculata; moderate Bowman-Birk inhibitor content, low lectin content), lupin seeds (Lupinus angustifolius; low lectin and protease inhibitor content) or soya beans (Clycine max; high Kunitz inhibitor content, moderate Bowman-Birk inhibitor content, moderate lectin content) or diets containing low levels of raw kidney bean (Phaseolus vulgaris; high lectin content, low

Protease inhibitor and lectin concentrations and N and lipid levels were evaluated in 27 soya bean samples. All contained trypsin and chymotrypsin inhibiting activity and lectin. Shinano midori, Shinano wasediro, Shinano‐oomame and Tsuronoku had high protein contents and average lipid levels, and their lectin and trypsin and chymotrypsin inhibitory activities were not unduly high. These lines, in particular, merit further nutritional evaluation. Food intake, feed conversion efficiency and growth by rats was reduced when soya bean was included in their diet, but the extent to which these parameters were affected did not appear to depend only on the protease inhibitor or lectin content. In contrast, pancreatic and small intestinal growth did seem to reflect the levels of these factors in the diet. Chymotrypsin inhibitor activity in soya bean was more readily abolished by heat‐treatment than was trypsin inhibitory activity. Lectin activity was also relatively heat‐resistant. However, all of these activities could be abolished by aqueous heat‐treatment of fully imbibed seeds at 100°C for 10 min. The effects of a soya diet on pancreas and small intestine weights were also abolished by this pre‐treatment, and food intake and nutrient utilisation by rats was greatly improved. © 1998 Society of Chemical Industry

: Protease inhibitor and lectin concentrations and N and lipid levels were evaluated in 27 soya bean samples. All contained trypsin and chymotrypsin inhibiting activity and lectin. Shinano midori, Shinano wasediro, Shinanooomame and Tsuronoku had high protein contents and average lipid levels, and their lectin and trypsin and chymotrypsin inhibitory activities were not unduly high. These lines, in particular, merit further nutritional evaluation. Food intake, feed conversion efficiency and growth by rats was reduced when soya bean was included in their diet, but the extent to which these parameters were a †ected did not appear to depend only on the protease inhibitor or lectin content. In contrast, pancreatic and small intestinal growth did seem to reÑect the levels of these factors in the diet. Chymotrypsin inhibitor activity in soya bean was more readily abolished by heat-treatment than was trypsin inhibitory activity. Lectin activity was also relatively heat-resistant. However, all of these activities could be abolished by aqueous heat-treatment of fully imbibed seeds at 100¡C for 10 min. The e †ects of a soya diet on pancreas and small intestine weights were also abolished by this pre-treatment, and food intake and nutrient utilisation by rats was greatly improved.1998 Society of Chemical Industry ( J Sci Food Agric 78, 225È231 (1998)