title: Inhibition of polyphenoloxidase activity by mixtures of heated cysteine derivatives with carbonyl compounds.
abstract: It had previously been shown that soluble Maillard reaction products (MRP) made from thiol compounds and glucose or fructose contained powerful inhibitors of various fruit and vegetable polyphenoloxidase (PPO) activity. In MRP from cysteine and glucose, the amount of hydroxymethylfurfural (HMF) formed increased with the increase in glucose concentration (0-1 M), particularly under acidic (pH 2) conditions. Using model mixtures containing a preheated cysteine-derived compound and a carbonyl component, especially HMF, furfural and benzaldehyde, we showed that the neoformed compounds produced exhibited a stronger inhibitory potency toward PPO activity of eggplant, apple, and mushroom than former MRP. Optimal reaction conditions for the formation of inhibitory compounds when HMF reacted with preheated cysteine were investigated. It was found that a reactants molar ratio of 1:1 and a reaction time exceeding 1 h were the most efficient reaction conditions to generate inhibitory compounds. The stability of the newly formed products, evaluated during storage, showed that their inhibitory potency was globally kept at 4, 21, and 37 degrees C for 72 h but was unstable when stored at -20 degrees C and lost when exposed to UV radiations for 24 h.
authors.affiliation: UMR SCALE 1211 (CNAM-ENSIA-INRA), Conservatoire National des Arts et Métiers (CNAM), Chaire de Biochimie Industrielle et Agro-Alimentaire, Paris, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chériot
authors.forename: Catherine
authors.initials: C
authors.lastname: Billaud
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Maillard
authors.forename: Jacques
authors.initials: J
authors.lastname: Nicolas
mesh_terms: D000363:Agaricales / Q000201:enzymology; D004156:Catechol Oxidase / Q000037:antagonists & inhibitors*; D003545:Cysteine / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D005662:Furaldehyde / Q000031:analogs & derivatives / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D015416:Maillard Reaction; D027845:Malus / Q000201:enzymology; D032323:Solanum melongena / Q000201:enzymology; D012996:Solutions
chemical_list: D004791:Enzyme Inhibitors; D012996:Solutions; C008046:5-hydroxymethylfurfural; D005662:Furaldehyde; D004156:Catechol Oxidase; D005947:Glucose; D003545:Cysteine