Polyphenol Oxidase Inactivation by Microwave Oven and Its Effect on Phenolic Profile of Loquat (<i>Eriobotrya japonica</i>) Fruit
Polyphenol Oxidase Inactivation by Microwave Oven and Its Effect on Phenolic Profile of Loquat (<i>Eriobotrya japonica</i>) Fruit作者机构：Departamento de Ingeniería Bioquímica Escuela Nacional de Ciencias Biológicas Instituto Politécnico Nacional México D.F. México Espectrometría de Masas y RMN Centro de Nanociencias y Micro y NanoTecnología México D.F. México Instituto de Salud Pública Universidad de Chalcatongo Chalcatongo de Hidalgo Oaxaca México.
出 版 物：《Food and Nutrition Sciences》 (食品与营养科学（英文）)
年 卷 期：2013年第4卷第9期
页 面：87-94页
学科分类：1008[医学-中药学(可授医学、理学学位)] 1006[医学-中西医结合] 100602[医学-中西医结合临床] 10[医学]
主 题：Loquat Phenolic Compounds Polyphenol Oxidase Microwave Eriobotrya japonica
摘 要：The objective of this research was investigated the effect of polyphenol oxidase microwave treatment on phenolic composition, antioxidant activity and microstructure of loquat fruit. Phenolic profile of methanolic extracts prepared from fresh, and microwave-treated samples were analyzed. Antioxidant activity was also evaluated by 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS?+) and 1,1-diphenyl-2-picrylhydrazyl (DPPH+) methods. In addition, polyphenol oxidase inactivation was carried out using a response surface methodology to establish the optimal conditions of treatment. The phenolic content of fresh mesocarp was 311 ± 0.60 mg gallic acid equivalents (GAE)/100g dry weight (DW) and that of microwave-treated mesocarp was 1230 ± 0.36 mg GAE/100g DW. Total phenolic content of water/ methanol extract significantly increases after microwave treatment rather than methanolic extract of fresh loquat. Five glycoside phenolics were identified by HPLC-DAD-MS as 3-caffeoylquinic acid, 3-p-coumaroylquinic acid, 5-caffeoylquinic acid and quercetin-3-O-sambubioside. Methanolic extract of microwave-treated mesocarp showed higher antioxidant activity than that of fresh mesocarp. Thus, polyphenol oxidase inactivation by microwave energy preserved the integrity of phenolic compounds as well as antioxidant activity in mesocarp extracts prepared from loquat fruit. It was also noted that phenolics were more abundant in the microwaved samples than in the fresh samples.
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