Effects of infrared treatment on urease, trypsin inhibitor and lipoxygenase activities of soybean samples

In this study, infrared (IR) treatment at different powers (814 W, 1003 W, 1208 W, 1342 W) and times (10 min, 15 min) were applied to unsoaked and soaked (30 min, 45 min) soybeans (cvs. Adasoy, Nazlican). Effects of IR treatment on urease, trypsin inhibitor, lipoxygenase-1 and lipoxygenase-3 activities were investigated. Infrared treatment caused a substantial reduction in urease and trypsin inhibitor activities and considerable decrease was observed as the IR power increased. Urease inactivation in unsoaked samples was achieved at even lower power (1208 W). In contrast to urease activity, IR treatment had a more pronounced effect on trypsin inhibitor and lipoxygenase activities of soaked soybeans as compared to unsoaked counterparts. Maximum trypsin inhibitor reduction in IR-treated samples was 95% for cv. Adasoy and 97% for cv. Nazlican. IR power of 1003 W was sufficient for complete inactivation of lipoxygenase-1 and lipoxygenase-3, regardless of the moisture contents of the samples.