Acid-formed pectin gel delays major incomplete kiwi fruit allergen Act c 1 proteolysis in in vitro gastrointestinal digestion

BACKGROUND: It is thought that food sensitisers must be able to reach the intestine in order to sensitise patients. Pectin is a gel-forming plant polysaccharide that can protect allergens from in vivo gastric digestion and in vitro pepsin digestion. The aim of this study was to examine if pectin gel formed in the acidic environment of the stomach can protect labile allergen from in vitro gastrointestinal digestion. RESULTS: Pectin forms a gel in the acidic conditions of gastric fluid up to a concentration of 1.0 +/- 0.14 g L(-1). Four allergenic fruits (kiwi, cherry, apple and banana) form gels in the same manner at the dilutions 14.8 +/- 0.4; 8.4 +/- 0.2, 9.4 +/- 0.35 and 29.1 +/- 0.2, respectively. The time necessary for dissolution of 50 g L(-1) pectin gel in intestinal fluid was found to be 70 +/- 0.2 min. Pectin gel formed in situ was able to protect Act c 1 from pepsin digestion for 1 h and from further intestinal digestion for one additional hour. CONCLUSION: Pectin gel in an acidic environment protects Act c 1 from pepsin digestion and dissolves slowly in the slightly basic environment of the intestine allowing the survival of fruit allergen for additional time and possible interaction with the gut immune system. (C) 2008 Society of Chemical Industr