Lipoxygenase isozymes and trypsin inhibitor activities in soybean as influenced by growing location

Lipoxygenase isozymes, responsible for the off-flavour associated with soy-based foods, and trypsin inhibitor, that affects protein digestibility, are two undesirable biological components present in soybean. The information on influence of growing location on lipoxygenase isozymes and trypsin inhibitor is negligible. The dry seeds of seven Indian soybean varieties, grown at four locations widely differing in latitude and therefore climate, were evaluated for isozymes of lipoxygenase and trypsin inhibitor. Variation in different varieties, at different locations, for the activities of lipoxygenase-I and lipoxygenase-II+III ranged from 450 to 2042 and 118 to 600 units per gramme of soy flour, respectively, while, for trypsin inhibitor, it varied from 42 to 113 mg per gramme of soy flour. Averaged over seven genotypes, Palampur, the coolest location, showed maximum mean values for Lox-I as well as Lox-II+III, indicating the influence of minimum mean temperature prevalent from flowering to maturity on lipoxygenase activitity. Genotypic, locational and genotypic×locational variations were found to be significant for Lox-I as well as Lox-II+III activity. Genotypic variation and genotypic×locational interaction were found to be significant for trypsin inhibitor activity.