Soybean allergy: Effect of genetic modification (GM), heat and enzymatic treatment on overall allergenicity

Soybean allergy affects approximately 0.4% of children worldwide. At least 16 proteins in soybean bind IgE from some soybean allergic subjects. Although the relative allergenic importance and abundance of individual proteins in soybean varieties is not understood, the allergenicity assessment guideline for the safety of genetically modified (GM) food crops (Codex, 2003) includes assessing potential increases in expression of endogenous allergens in an allergenic crop like soybeans that might be due to insertion of the new DNA. The studies described in this dissertation included comparison of binding of IgE from individual soybean allergic subjects to proteins in three transgenic soybean lines, their respective near-isogenic and other commercial lines. The results indicated no evidence that the transgenic soybean lines present an increased risk for soybean allergic subjects especially since those with soybean allergy should avoid all soybeans. Furthermore, based on the observed variation among commercial lines, it is not clear that similar tests are useful to evaluate food safety for typical GM varieties. Soybean products are widely used in food because of their functionality, nutritional properties and low cost. Some soybean ingredients are processed either by heat treatment or enzymatic hydrolysis to attain desirable functional properties or in some cases to reduce the allergenicity. However, few studies have investigated the effect various processing conditions have on allergenicity of soybean products and their efficacy in reducing allergenicity of soybean. Additional studies described in this dissertation evaluated potential changes in IgE binding to soybean proteins that are heat-treated under conditions that mimic some commercial processing or undergo enzyme hydrolysis. Results indicated that majority of thermal treatment conditions utilized in making soybean products will not affect their allergenicity and hydrolysis of soybean proteins by different enzymes does not make them less allergenic compared to the untreated proteins and may increase their allergenicity