Enzymatic hydrolysis: A method in alleviating legume allergenicity

- Effect of two enzymes, alcalase and flavourzyme on the allergenicity of kidney bean, black gram and peanut was investigated.
- Enzymatic hydrolysis reduces the allergenicity of protein extracts significantly in ELISA and immunoblot.
- Further hydrolysates showed significantly reduced histamine release and reduced skin test reactivity in sensitive patients.
- Hydrolysates lost their allergenic potential as they were unable to inhibit the IgE binding in competitive ELISA.
- This method may be used for preparation of hypoallergenic foods.

Legumes are involved in IgE mediated food allergy in many countries. Avoidance of allergenic food is the only way to avoid symptomatic reaction. The present study investigated the effect of enzymatic hydrolysis on the allergenicity of three legumes - kidney bean (Phaseolus vulgaris), black gram (Vigna mungo) and peanut (Arachis hypogaea). Soluble protein extracts of the study legumes were sequentially treated by Alcalase® and Flavourzyme®. Allergenicity of hydrolysates was then determined by ELISA, immunoblot, stripped basophil histamine release and skin prick test (SPT). Hydrolysis resulted in the loss of all IgE binding fractions determined by immunoblot in the three legumes. Specific IgE binding in ELISA was reduced by 62.2 ± 7.7%, 87.1 ± 9.6% and 91.8 ± 7.2% in the hydrolysates of kidney bean, black gram and peanut, respectively (p < 0.01). The release of histamine was decreased significantly when sensitized basophils were challenged with hydrolysates as compared to raw extracts. Significant reduction in the biopotency of hydrolysates was also observed in SPT where only 1/10 kidney bean-sensitive individuals, 2/6 black gram-sensitive individuals and 1/7 peanut-sensitive individuals were found positive to their respective hydrolysates. In conclusion, enzymatic hydrolysis is effective in attenuating allergenicity of legume proteins and may be employed for preparing hypoallergenic food extracts.