Green tea catechins of food supplements facilitate pepsin digestion of major food allergens, but hampers their digestion if oxidized by phenol oxidase

The in vitro gastric digestion of several food allergens (beta-lactoglobulin (BLG), alpha-lactalbumin (LA) and peanut allergens (PE)) in the presence of a catechin-enriched polyphenol extract of green tea (GTC), oxidized polyphenols and phenol oxidase processed food allergens and GTC was investigated. Pepsin-resistant proteins, such as BLG, major peanut allergens, Ara h 1 and Ara h 2, degrade faster in the presence of catechin-enriched green tea polyphenols. Phenol oxidase polymerized GTC affected adversely protein digestion of BLG and LA, but not digestion of PE proteins. Protecting effect of polyphenols correlated well with the ability of proteins to form insoluble complexes with oxidized catechins. Cross-linking of proteins and polyphenols further extended the half-lives of BLG and LA in the in vitro digestion by pepsin. Catechin-enriched green tea polyphenols of food supplements facilitate pepsin digestion of major food allergens, but hamper their digestion if oxidized and polymerized by phenol oxidase.

► GTC activate pepsin digestion of cow’s milk (BLG and LA) and peanut allergens (PE).
► GTC make PE allergens more soluble, thus contributing to pepsinolysis.
► Polymerization products of GTC protected BLG and LA from pepsin-digestion.
► The no hampering effect was observed on peanut allergens.
► PE proteins remained soluble in the presence of polymerized GTC.