Allergome of oral-gastric in vitro digest of roasted hazelnut shows stronger IgE binding compared to the raw counterpart

Abstract

Background: In vitro pepsin digestion is important factor when assessing protein foodallergenicity. Roasted hazelnut is more common in human nutrition than a raw hazelnut;however, all studies were focused on Cor a 9 allergen obtained from a raw hazelnut. Thereare only two studies employing in vitro INFOGEST digestion harmonized protocol onhazelnut with its full matrix. The aim of this study was to assess immunoreactivity of rawand roasted hazelnut gastric digests and to compare secondary/tertiary structure of Cor a 9allergen purified from these two sources.Methods: Digestion resistant protein fragments were analysed by 1D/2D electrophoresis.Following digestion, IgE binding from patients’ pooled sera and by specific antibodies, wereassessed in ELISA and immunoblot. CD spectroscopy was applied for Cor a 9 structuralanalyses.Results: Cor a 11 and acidic forms of Cor a 9 were more prone to pepsin proteolysis, yettheir large fragments survived partially. Cor a 8 was protected by lipids, retaining capabilityto bind its specific antibody. Roasting did not significantly affect secondary structure of themost abundant hazelnut allergen, Cor a 9.Conclusion: Roasting of hazelnut seems to boost IgE binding derived from pooled sera ofhazelnut allergic patients with oral-gastric allergen digests.