Effect of thermal processing and γ-irradiation on allergenicity of legume proteins

Legumes are implicated in IgE mediated food allergy in different countries. The present study aimed to investigate the effect of different processing methods on allergenicity of legume proteins. The extracts were processed by boiling, γ-irradiation or by combination of both. The changes in soluble protein content, specific IgE binding and allergenic potential of legume proteins were assessed. Thermal processing resulted in a 3- to 4-fold reduction in soluble protein. Specific IgE binding was reduced 74±6.5%, 83±11.6% and 62±7.2% in the soluble protein of kidney bean, black gram and peanut, respectively, after boiling (p<0.01) whereas there was 34±5.2%, 74±15.6% and 44±11.1% IgE binding reduction in the insoluble protein fraction of respective legumes. Boiling followed by γ-irradiation reduced IgE binding significantly (p<0.05). Biopotency of soluble protein of kidney bean, black gram and peanut was reduced 7-, 3- and 26-folds (p<0.001), respectively, and that of insoluble protein decreased 6-, 4- and 8-folds (p<0.001), respectively, after boiling. Combination treatment was effective in reducing the potency of both soluble and insoluble protein significantly as compared to boiling alone (p<0.001). However, γ-irradiation alone did not bring any change in allergenicity. In conclusion, boiling followed by γ-irradiation is effective in attenuating allergenicity of legume proteins.