title: Apple polyphenoloxidase inactivation during heating in the presence of ascorbic acid and chlorogenic acid.
abstract: It was recently reported that during osmotic dehydration of ascorbic acid (AA)-treated apple cubes, losses in AA and phenolics could partly arise from enzymatic oxidation, provided polyphenoloxidase (PPO) was still active under the processing conditions. To determine the impact of dehydration temperatures on PPO action, as well as chemical and enzymatic oxidation reactions, apple PPO inactivation alone or with AA (1mM) and/or chlorogenic acid (CG, 3mM), as well as AA and CG levels evolution, during heating of the model solutions at 45 and 60°C were investigated. At pH 3.8, PPO was still functional, keeping 61 and 4% residual activity after 2h of heating at 45 and 60°C, respectively. The combined treatment of heating and AA was more effective in reducing PPO activity, while incubation at 60°C with AA and CG minimised the losses of PPO activity. CG remained stable during heating, even in the presence of AA which, in turn, was more affected by heating. Thus, during heating, provided PPO remained active with enough available O2 in the model systems, CG oxidation and coupled oxidoreduction with AA could readily develop.
authors.affiliation: Conservatoire National des Arts et Métiers, Chaire de Biochimie Industrielle et Agro-Alimentaire, UMR 1145 Ingénierie Procédés Aliments, 75141 Paris cedex 03, France; INRA, UMR 1145 Ingénierie Procédés Aliments, 91300 Massy, France. Electronic address: yin-nai.chow@laposte.net.
authors.forename: Yin-Naï
authors.initials: YN
authors.lastname: Chow
authors.affiliation: Conservatoire National des Arts et Métiers, Chaire de Biochimie Industrielle et Agro-Alimentaire, UMR 1145 Ingénierie Procédés Aliments, 75141 Paris cedex 03, France. Electronic address: loic.louarme@cnam.fr.
authors.forename: Loïc
authors.initials: L
authors.lastname: Louarme
authors.affiliation: AgroParisTech, UMR 1145 Ingénierie Procédés Aliments, F-91300 Massy, France; INRA, UMR 1145 Ingénierie Procédés Aliments, 91300 Massy, France. Electronic address: catherine.bonazzi@agroparistech.fr.
authors.forename: Catherine
authors.initials: C
authors.lastname: Bonazzi
authors.affiliation: Conservatoire National des Arts et Métiers, Chaire de Biochimie Industrielle et Agro-Alimentaire, UMR 1145 Ingénierie Procédés Aliments, 75141 Paris cedex 03, France. Electronic address: jacques.nicolas@cnam.fr.
authors.forename: Jacques
authors.initials: J
authors.lastname: Nicolas
authors.affiliation: Conservatoire National des Arts et Métiers, Chaire de Biochimie Industrielle et Agro-Alimentaire, UMR 1145 Ingénierie Procédés Aliments, 75141 Paris cedex 03, France. Electronic address: catherine.billaud@cnam.fr.
authors.forename: Catherine
authors.initials: C
authors.lastname: Billaud
keywords: Ascorbic acid; Chlorogenic acid; Osmotic dehydration; Oxidation; Polyphenoloxidase; Postharvest processing; Thermal treatment