Submitted to: Journal of Food Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/16/2003
Publication Date: 1/31/2004
Citation: Brandon, D.L., Bates, A.H., Friedman, M. 2004. Immunoassays for Bowman-Birk and Kunitz soybean trypsin inhibitors in infant formula. Journal of Food Science. 69(1):45-49. Interpretive Summary: Adverse nutritional effects following consumption of raw soybean meal have been attributed in part to the presence the Bowman-Birk and Kunitz inhibitors of digestive enzymes which account for about 6% of the protein of soybeans. On the other hand, it has also been reported that BBI can prevent cancer in animals. We developed "sandwich" immunoassays which are ideal for high throughput analysis of the soybean inhibitors of digestive enzymes in soybeans seeds resulting from breeding and plant molecular biology programs, the fate of the inhibitors in processed foods, and their role in cancer prevention.
Technical Abstract: Because the consumption of soybean inhibitors of digestive enzymes can have both beneficial and adverse effects, reliable and rapid analytical methods are needed for these inhibitors in processed foods, such as soy infant formulas. Monoclonal antibody-based sandwich enzyme-linked immunosorbent assays (ELISAs) were developed for the two major protease inhibitors of soybean, the Kunitz trypsin inhibitor (KTI) and Bowman-Birk inhibitor (BBI) of trypsin and chymotrypsin. The limit of detection of the ELISAs was approximately 1 ng/mL for each inhibitor. Suitable combinations of antibodies consisted of monoclonal antibody for capture, with use of a second monoclonal antibody, labeled with either biotin or horseradish peroxidase, for detection. For KTI, a rabbit antibody also was effective as detection antibody, with a peroxidase goat anti-rabbit antibody for enhancement and colorimetric determination. The assays were used to measure active inhibitors in soy infant formulas and soy isolates, and the sandwich ELISA for BBI was also effective in detecting soybeans with altered levels of BBI.