Impact of Culinary Treatments on the Immunoreactivity of Soy Protein Isolates

The reduction in the immunoreactive properties of soy proteins is crucial, considering the widespread use of soy in food, including protein isolates. This study aimed to evaluate the effects of various culinary treatments on the immunoreactivity of whole soybeans and isolated 7S and 11S protein fractions. Soybean and the isolated 7S and 11S fractions were subjected to boiling (100 °C for 60 and 120 min), pressure cooking (120 °C, 202 kPa for 50 min), and microwave heating (360 W for 30 min). The immunoreactivity of the samples was assessed using ELISA and Western blotting. Culinary treatment of whole soybeans, regardless of the method, decreased the content of immunoreactive 7S and 11S fractions by approximately 30%. Culinary processing of the isolated 7S and 11S proteins, in the absence of the protective seed matrix, resulted in a more pronounced reduction in immunoreactivity. Pressure-cooking allowed for the reduction of the content of immunoreactive 7S and 11S proteins by 71 and 58%, respectively. Western blotting confirms a decrease in both 7S and 11S immunoreactive bands, with a more marked reduction observed for the 11S fraction. These findings indicate that such a reduction may be sufficient to lower the risk of allergic reactions in individuals with mild soy allergy. However, the persistence of immunoreactive bands even after intensive treatment suggests that culinary methods alone are unlikely to ensure safety for highly sensitized individuals.