Changes in Trypsin Inhibitory Activity in Some Soybean Varieties During Maturation and Germination

Trypsin inhibitory activity (TIA) of 4 varieties (var) of soybeans was measured. Values (mg/g soybean) represent TIA extracted under conditions employed and are equivalent to a weighed amount of crystallized soybean trypsin inhibitors (TI). As the beans matured, the amount of TIA in the extract increased Dare variety had the sharpest increase, 13.4‐27.5 mg/g. Mean mdg of TI for Kanrich was 22.5; Verde, 21.7; Soylima, 17.5; and Dare, 21.8. Dehulled beans held 2.5 min in boiling water had 97–98% of the extractable TIA destroyed. Rinsing beans in water removed up to 10.2% TIA. Removing the testa from unrinsed beans reduced TIA up to 4.3%. Decorticated, rinsed cotyledons remined 50.9% (Soylima) to 80.6% (Verde) of the extractable TIA. Beans which were soaked, germinated 3 days and rinsed twice daily lost up to 13.2% TIA.