[Objectives] To study the polyphenol oxidase (PPO) activity and total phenol content of Docynia indica .[Methods] The tender branches and petioles of the medicinal and edible plant D. indica were used as experimental ...[Objectives] To study the polyphenol oxidase (PPO) activity and total phenol content of Docynia indica .[Methods] The tender branches and petioles of the medicinal and edible plant D. indica were used as experimental materials, and the annual changes of total phenol content and polyphenol oxidase (PPO) activity were analyzed.[Results] pH 7.0 was the optimum value of polyphenol oxidase activity in D. indica plants;the best substrate was catechol with the concentration of 0.15 mol/L;the optimum temperature was 25 ℃.[Conclusions] The total phenol content of D. indica plants was the lowest in April, May and September of each year. The polyphenol oxidase activity of D. indica plants at flowering and fruiting stage was significantly higher than that at pre-flowering stage.展开更多
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 ext...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.展开更多
In researches, were evaluated 103 strains of 25 species of xylotrophic micromycetes causing white decay which spreads in ecologically different regions of Azerbaijan for the synthesis of phenoloxidases (laccase, perox...In researches, were evaluated 103 strains of 25 species of xylotrophic micromycetes causing white decay which spreads in ecologically different regions of Azerbaijan for the synthesis of phenoloxidases (laccase, peroxidase, and ligninase). It was determined that strains belonging to species such as Cerena unicolar, Pleurotus ostreatus, Schizophyllum commune and Trametes versicolor are more actively synthesized phenoloxidase and this process generally occurs by the inductive way. Despite this, unlike from classic inductive enzymes basal level of phenoloxidases in the basidiomycetes is much higher, which can be characterized as the sign adaptation of xylotroph macromisets to live in woody substrates.展开更多
基金Supported by Science and Technology Program of Sichuan Province(2018NZ0091)Special Project of Sichuan Provincial Public-Interest Scientific Institution Basal Research FundOpen Fund for Key Laboratory of Coarse Cereal Processing,Ministry of Agriculture and Rural Affairs(2018CC12)
文摘[Objectives] To study the polyphenol oxidase (PPO) activity and total phenol content of Docynia indica .[Methods] The tender branches and petioles of the medicinal and edible plant D. indica were used as experimental materials, and the annual changes of total phenol content and polyphenol oxidase (PPO) activity were analyzed.[Results] pH 7.0 was the optimum value of polyphenol oxidase activity in D. indica plants;the best substrate was catechol with the concentration of 0.15 mol/L;the optimum temperature was 25 ℃.[Conclusions] The total phenol content of D. indica plants was the lowest in April, May and September of each year. The polyphenol oxidase activity of D. indica plants at flowering and fruiting stage was significantly higher than that at pre-flowering stage.
文摘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.
文摘In researches, were evaluated 103 strains of 25 species of xylotrophic micromycetes causing white decay which spreads in ecologically different regions of Azerbaijan for the synthesis of phenoloxidases (laccase, peroxidase, and ligninase). It was determined that strains belonging to species such as Cerena unicolar, Pleurotus ostreatus, Schizophyllum commune and Trametes versicolor are more actively synthesized phenoloxidase and this process generally occurs by the inductive way. Despite this, unlike from classic inductive enzymes basal level of phenoloxidases in the basidiomycetes is much higher, which can be characterized as the sign adaptation of xylotroph macromisets to live in woody substrates.
