The objective of this study is to determine the optimum processing temperature and time to inactivate soybean lectins in soybeans. Raw defatted soybean meal was steam-heated at temperatures between 90 to 120° C for five and twenty minutes in an autoclave. Results of these laboratory treatments indicated that increasing processing temperatures reduced the total carbohydrate-binding lectin, agglutinating lectins, urease activity and trypsin inhibitor. The researchers estimated that more than 90 percent of all of the antinutritional activity in the raw soybean meals were destroyed when the meals were heated to 100 °C for five minutes. The urease activity was highly correlated (r> 0.73) with soybean lectin activity, indicating that urease activity could be used to monitor lectin activity in commercial soybean meals. The researchers concluded that urease activities of 0.03 to 0.09 units of pH change indicated the meals were adequately processed and contained negligible lectin levels.
Fasina, Y.O. and co-workers. Poultry Sci. 82(4):648-856, 2003.