How is the trypsin inhibitor (TI) removed from soybeans?
A. There are both heat-stable (saponins, tannins, estrogens, phytate) and heat-labile (protease inhibitors) in soy. Protease inhibitors in soy are destroyed by heating but other factors also play a role, such as duration of heating, particle size and moistusre conditions. Thus, how soy products are processed will dictate how much of the protease inhibitor (also known as trypsin inhibitor) remains. For example, raw soy flour has lost none of the trypsin inhibitor, but toasted soy flour has lost 85-94%, and soy protein isolute has lost 79-91%. The loss of trypsin inhibitor does not reduce the biological value and digestibility of the protein. In fact, the opposite occurs. As measured by the Protein Efficiency Ratio (PER) assay in rats, a standard assay of protein quality, nutritive value of the protein in soy actually increases with the heating used to destroy trypsin inhibitors. Source: Karl E. Weingartner, Ph. D., Senior Food Scientist & Assistant Professor National Soybean Research La
