摘要
The capacity of five enzymes (P1-P5) to inactivate the trypsin inhibitory activity (TIA) and lectin in raw soybean (RS) and low temperature-extruded soybean (LTES) was examined. P1 is an acid fungal protease with pH optimum of 5 and P2, P3, P4 and P5 are bacterial proteases with pH optima of 7, 10, 8 and 8 respectively. The results indicated that all enzymes could reduce TIA to a varying degree at their optimum pH. The sequence of effectiveness was P3>P4>P5>P1>P2. The most effective enzyme, P3, reduced TIA to 38% and chymotrypsim inhibitory activity (CIA) to 9% of the original values. After six hours incubation at 50℃, the lectin concentration of LTES and RS was reduced by 50 and 17% respectively by P3, and by 42 and 29% by P4. In the second study, the best enzymes, P3 and P4, were incubated with RS or LTEs at different doses of 0, 0.10, 0.50% or 1.00% (w/w), for periods of 1, 2, 3, 6 or 12 hours. After one hour incubation with P3 at 1.00%, TIA of RS was reduced from 36.60 to 13.30 mg·g -1 . The corresponding values for LTES were 24.50 and 1.90 mg·g -1 . When the incubation was extended to 12 hours, the remaining TIA was 0.90 for LTES and 1.20 mg·g -1 for RS. P4 was not as effective as P3 up to six-hour incubation, but after twelve hours it achieved a similar reduction in activity to that of P3. A kinetic analysis of data showed that the inactivation process of purified soyabean trypsin inhibitors by P3 followed first-order chemical kinetics (Ct=90.90 -0.0408t , r=0.99). The rate of denaturation was -0.0408 per minute. It is concluded that the use of selected enzymes for anti-nutritive factors (ANFs) is an exciting possibility, but still requires further development.
The capacity of five enzymes (P1-P5) to inactivate the trypsin inhibitory activity (TIA) and lectin in raw soybean (RS) and low temperature-extruded soybean (LTES) was examined. P1 is an acid fungal protease with pH optimum of 5 and P2, P3, P4 and P5 are bacterial proteases with pH optima of 7, 10, 8 and 8 respectively. The results indicated that all enzymes could reduce TIA to a varying degree at their optimum pH. The sequence of effectiveness was P3>P4>P5>P1>P2. The most effective enzyme, P3, reduced TIA to 38% and chymotrypsim inhibitory activity (CIA) to 9% of the original values. After six hours incubation at 50℃, the lectin concentration of LTES and RS was reduced by 50 and 17% respectively by P3, and by 42 and 29% by P4. In the second study, the best enzymes, P3 and P4, were incubated with RS or LTEs at different doses of 0, 0.10, 0.50% or 1.00% (w/w), for periods of 1, 2, 3, 6 or 12 hours. After one hour incubation with P3 at 1.00%, TIA of RS was reduced from 36.60 to 13.30 mg·g -1 . The corresponding values for LTES were 24.50 and 1.90 mg·g -1 . When the incubation was extended to 12 hours, the remaining TIA was 0.90 for LTES and 1.20 mg·g -1 for RS. P4 was not as effective as P3 up to six-hour incubation, but after twelve hours it achieved a similar reduction in activity to that of P3. A kinetic analysis of data showed that the inactivation process of purified soyabean trypsin inhibitors by P3 followed first-order chemical kinetics (Ct=90.90 -0.0408t , r=0.99). The rate of denaturation was -0.0408 per minute. It is concluded that the use of selected enzymes for anti-nutritive factors (ANFs) is an exciting possibility, but still requires further development.
