Heat treatments applied to egg product have a rather low impact on in vivo allergenicity, despite significant changes in protein digestibility and antigenicity

Egg products represent 15 to 50% of egg consumption in Europe depending on the country. For microbiological safety reasons, thermal treatments are applied to egg products. Liquid egg products are pasteurized for 2 to 6 min around 56°C (egg white) or 68°C (for whole egg and yolk); egg white powders are dry-heated up to several weeks from 60 to 80°C. The effects of these treatments on egg functional properties have been widely studied, but what about egg protein digestibility or allergenicity? The aim of our study was to investigate the effect of a wide range of pasteurization rates (on liquid whole egg) and dry heating rates (on egg white powder) on the in vitro digestibility, antigenicity and allergenicity of egg proteins.Pasteurization of liquid whole egg up to 10 min at 60°C, improved protein in vitro digestibility and decreased ovomucoïd antigenicity. Conversely, pasteurization up to 10 min at 66°C decreased protein in vitro digestibility and lysozyme antigenicity, but increased drastically ovotransferrin antigenicity. However pasteurization (6 min at 66°C) had a limited impact on the prick test (PT) reactivity of most children. Dry heating of egg white powder, from 1 to 10 days at 60°C, improved protein in vitro digestibility and slightly decreased lysozyme antigenicity. But dry heating over 1 day at 80°C or 90°C decreased protein in vitro digestibility and lysozyme antigenicity, while drastically increased ovotransferrin antigenicity. Dry heating of egg white powder up to 7 days at 80°C had a limited impact on egg allergy tested in mice.