Effect of partial hydrolysis on the hazelnut and soybean protein detectability by ELISA

Food allergies represent an increasing food safety problem. Soybean and hazelnut are identified as major food allergens and were selected for this study. During production of the hypo-allergenic formulae or other food products cross-contamination may occur. It is therefore important to have reliable analytical methods able to detect traces of allergenic proteins even after they have undergone partial hydrolysis. Soybean and hazelnut proteins were partially hydrolysed with pepsin and the impact on the detectability by commercial kits was evaluated. Hazelnut proteins were more prone to peptic hydrolysis as evidenced by the SDS-PAGE pattern and the increase in the non-protein fraction. Two kits (Veratox and Hazelnut Residue) were able to detect hazelnut proteins even after 180 min of hydrolysis. Moreover, the detectability by the Veratox kit seemed to be improved when analysing hydrolysed proteins. The detectability of hazelnut proteins by the Ridascreen® FAST kit was severely affected by as little as 30 min of hydrolysis. For soybean proteins an overestimation of the real protein concentration was observed for two kits (Veratox and BioKits) and decreases in detectability after 180 min of hydrolysis was observed for all the tested kits.