The Effect of the Food Matrix on the In Vitro Bio-Accessibility and IgE Reactivity of Peanut Allergens

Abstract

Scope: Factors such as food processing, the food matrix, and antacid medication may affect the bio-accessibility of proteins in the gastrointestinal tract and hence their allergenic activity. However, at present they are poorly understood. Methods and Results: Roasted peanut flour was incorporated into either a chocolate dessert or cookie matrix and bio-accessibility were assessed using an in vitro digestion system comprising a model chew and simulated gastric and duodenal digestion. Protein digestion was monitored by SDS-PAGE and immunoreactivity analyzed by immunoblotting and immunoassay. IgE reactivity was assessed by immunoassay using serum panels from peanut-allergic subjects. Roasted peanut flour proteins proved highly digestible following gastro-duodenal digestion even when incurred into a food matrix, with only low molecular weight polypeptides of Mr < 8 kDa remaining. When gastric digestion was performed at pH 6.5 (simulating the effect of antacid medication), peanut proteins are not digested; subsequent duodenal digestion is also limited. IgE reactivity of the major peanut allergens Ara h 1, Ara h 2, and Ara h 6, although reduced, was retained after oral-gastro-duodenal digestion irrespective of digestion conditions employed. Conclusion: Peanut allergen bio-accessibility is unaffected by the dessert or cookie matrices whilst high intra-gastric pH conditions render allergens more resistant to digestion.