Green tea catechins of food supplements facilitate pepsin digestion of major food allergens, but hampers their digestion if oxidized by phenol oxidase Ziyad Tantoush, Danijela Apostolovic, Bojana Kravic, Ivana Prodic, Luka Mihajlovic, Dragana Stanic-Vucinic, Tanja Cirkovic Velickovic * University of Belgrade, Faculty of Chemistry, Studentski trg 16, 11000 Belgrade, Serbia ARTICLE INFO Article history: Received 15 November 2011 Received in revised form 13 April 2012 Accepted 16 April 2012 Available online xxxx Keywords: Allergen Catechin Green tea Digestibility Food allergy Peanut ABSTRACT 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 polyphe- nol 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. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Digestion helps release of bioactive food components, but also exerts an influence on immunopathologies, such as food allergy and intestinal bowel disease. An impairment of gastric digestion has recently been linked to an increased risk of food allergies (Untersmayr & Jensen-Jarolim, 2008). Many food allergens sensitizing via the gastrointestinal tract are struc- turally stable and resistant to denaturation, heating and pep- sin digestion (Astwood, Leach, & Fuchs, 1996). Testing allergen susceptibility to pepsin is included in testing of the allergy risk of proteins introduced in foods by genetic manip- ulation ( Schnell & Herman, 2009; Wickham, Faulks, & Mills, 2009). Various in vitro digestion models have been developed to assess the stability of food allergens during digestion, but systematic evaluation of the stability of food allergens that are active via the gastrointestinal tract have been currently tested in traditional pepsin digestibility models (Ladics, 2008; Thomas et al., 2004). In addition, more evidence is build- ing up on the influence of food processing on pepsin digestion and allergenicity of proteins (Mills & Mackie, 2008; Monogiou- di et al., 2011; Roth-Walter et al., 2008; Stanic et al., 2010). The effect of some phenolic compounds, resveratrol, cate- chin, epigallocatechin-3-gallate, quercetin and phenolics-rich beverages (red wine and green tea) on pepsin activity has pre- viously been described. The tested polyphenols and beverages 1756-4646/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jff.2012.04.006 * Corresponding author. E-mail address: tcirkov@chem.bg.ac.rs (T. Cirkovic Velickovic). Abbreviations: BSA, bovine serum albumin; BLG, beta-lactoglobulin; GTC, catechin-enriched polyphenol extract of green tea; LA, alpha lactoalbumin; PE, peanut protein extract; PPO, phenol oxidase. JOURNAL OF FUNCTIONAL FOODS xxx (2012) xxx – xxx Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jff Please cite this article in press as: Tantoush, Z. et al., Green tea catechins of food supplements facilitate pepsin digestion of major food allergens, but hampers their digestion if oxidized by phenol oxidase, Journal of Functional Foods (2012), http://dx.doi.org/10.1016/j.jff.2012.04.006