IgE-binding and in vitro gastrointestinal digestibility of egg allergens in the presence of polysaccharides

This work studies the IgE-binding and in vitro gastrointestinal digestibility of the main egg allergens, ovalbumin (OVA) and ovomucoid (OM), in the presence of pectin (P), gum arabic (G) and xylan (X), functional biopolymers commonly used in the food industry. To this aim, solutions of OVA or OM and P, G or X were digested by using a model that mimics physiological conditions. Gastric and duodenal digests were analysed by SDS-PAGE, RP-HPLC and SEC and the specific human-IgE binding capacity was assessed by immunoblotting and ELISA using sera from egg-sensitized patients. The reactivity towards human IgE of OVA and OM was considerably increased in the presence of the polysaccharides and their susceptibility to digestion was diminished when compared with the isolated proteins. As a result, the duodenal digests obtained in the presence of polysaccharides retained more IgE-binding than the isolated protein digests. Overall, the present results underline the importance of the food matrix in the digestibility of food allergens and in their potential to trigger an immune response.