The influence of extrusion or boiling on trypsin inhibitor and lectin activity in leguminous seeds and protein digestibility in rats

摘要

Raw seeds (R) of pea (P), faba bean (F), and soybean (S) were extruded at 130, 150 or 170 deg C, or boiled in water without previous soaking for 5, 10 or 20 min. Trypsin inhibitors activity (TIA) in raw seeds of P, F and S amounted 2.3, 2.1 and 31.3, and after extrusion at 170 deg C it reached 0.1, 0.5 and 8.5 trypsin unit inhibited/mg sample (TIU/mg) in P, F and S, respectively. Ten minutes exposition in boiled water decreased TIA to 0.1, 0.1 and 0.4 TIU/mg, respectively. Haemagglutinin activity (HAA) assayed in raw seeds with guinea pig erythrocytes was 400, 100 and 800 in P, F and S, respectively. Extrusion at 170 deg C decreased HAA to 100, 0 and 100 in P, F and S, respectively. Extracts from faba bean and pea which had been boiled for 20 min did not agglutinate human erythrocytes. However, boiled soybean still showed agglutination activity at 200, 200, 100 and 400 for blood groups: 0, A, B and AB, respectively. It is concluded that for the nutritional purpose extrusion at 150 deg C is adequate for elimination of TIA and HAA in P and F, but in the case of S 170 deg C is required. However; ten minutes of exposition of raw seeds to boiling water is effective for elimination of TIA. Boiling for twenty minutes canceled HAA in faba bean and pea protein extracts, but it was not so efficient in the case of soybean. Rats fed diets with 10% of extruded leguminous seeds (150 deg C) had significantly increased apparent digestibility of dry matter and crude protein.