Impact of irradiation and thermal processing on the immunochemical detection of milk and egg allergens in foods

Abstract

There is little information available on the antigenicity of allergens in foods subjected to gamma irradiation and thermal processes. The objective of the study was to evaluate the effects of gamma irradiation and thermal processing on the recovery of milk and egg allergens in foods prepared using irradiated wheat flour incurred with these allergens. Bread, boiled pasta and extruded cereal were selected as food matrices for the study.Allergen detection was performed using Surface Plasmon Resonance (SPR) and commercially available enzyme linked immunosorbent assay (ELISA) kits. Protein structure was characterized using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and circular dichroism (CD) spectroscopy. The ELISA kits performed well in detecting allergens in the unprocessed flours with recoveries ranging from 63–120%. The results for dough and uncooked pasta were similar to those of unprocessed flours. Recoveries for boiled pasta were significantly (p≤0.05) reduced. The lowest allergen recoveries were obtained in bread samples. Allergen recoveries in gamma irradiated samples depended on the irradiation dose, the type of ELISA kit used, the tested matrix, and the processing method. FTIR and CD results showed that among the allergens casein was the most thermostable followed by ovomucoid. β-Lg and ovalbumin showed thermal sensitivity. In conclusion, gamma irradiation may affect the antigenicity of allergenic food residues at low levels depending on the food matrices and the processing methods.