Influence of polyphenol oxidase activity and polyphenol content of tea shoot on quality of black tea

1990 ◽  
Vol 51 (1) ◽  
pp. 57-69 ◽  
Author(s):  
S N Stephen Thanaraj ◽  
Ramachandran Seshadri
Keyword(s):  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Black Tea ◽  
Polyphenol Content ◽  
Polyphenol Oxidase Activity ◽  
Tea Shoot

Clonal plain back tea quality parameters responses of hard physical withered leaf to rehydration and fermentation durations

2016 ◽  
Author(s):  
P. Okinda Owuor ◽  
And Martin Obanda
Keyword(s):  
Sensory Evaluation ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Black Tea ◽  
Quality Parameters ◽  
Moisture Loss ◽  
Polyphenol Oxidase Activity ◽  
Tea Quality

Hard physical withers in tea processing result in reduced plain black tea quality parameters, but improve flavoury black tea quality. Chemical withers with minimal moisture loss improve plain black tea quality parameters. But chemical withered leaf is normally bulky and not flaccid thus reducing maceration rates. Hard physical withers reduce polyphenol oxidase activity, thereby impairing ability of the leaf to produce high amounts of plain black tea quality parameters, especially theaflavins and thearubigins. This study examined if rehydrating hard physical withered leaf could improve its fermentability and influence fermentation duration, and if such changes are cultivar dependent. Rehydrating hard physical withered leaf increased (p≤0.05) total theaflavins, thearubigins, brightness, total colour and sensory evaluation of resultant black teas. The patterns of the responses did not vary with cultivars or fermentation duration. The theaflavins and brightness declined (p≤0.05) while thearubigins and total colour increased (p≤0.05) with long fermentation durations irrespective of withering regime. Results demonstrate that problems of plain black tea quality reduction due to hard physical withers can be partially reversed by rehydration to chemical wither standard, but the withering regime does not influence when maximum plain black tea quality parameters are produced.

scholarly journals Effects of polyphenol content, polyphenol oxidase activity and pH on blackspot bruise of Japanese potato varieties

2006 ◽  
Vol 32 (2) ◽  
pp. 67-72
Author(s):  
Kazunori HIRONAKA ◽  
Ken-ichi ISHIBASHI ◽  
Hiroshi KOAZE ◽  
Hiroshi SHIRASAKA ◽  
Kiyoaki MATSUDA ◽  
...  
Keyword(s):  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Polyphenol Content ◽  
Polyphenol Oxidase Activity ◽  
Potato Varieties ◽  
Blackspot Bruise

scholarly journals Modificarea activității peroxidazei și a polifenoloxidazei în fructele de prun în funcție de influența SBA Reglalg, microelementelor (B, Zn, Mn, Mo) și a metodelor de păstrare

2020 ◽  
Author(s):  
Ana Popovici ◽  
◽  
Nicolae Bujoreanu ◽  
Valentina Svetlicenco ◽  
◽  
...  
Keyword(s):  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Atmospheric Conditions ◽  
Lower Intensity ◽  
Polyphenol Oxidase Activity ◽  
Synthetic Inhibitor ◽  
Duration Of Storage ◽  
Storage Methods ◽  
Fruit Preservation

When storaging the plum fruits of the varieties Stenley under normal atmospheric conditions and by the method of treating them with the synthetic inhibitor of ethylene Fitomag, the modification of peroxidase and polyphenol oxidase activity in fruits depended on the conditions and duration of storage, metabolic processes course in fruit during storage, the particularities of the varieties and their storage methods. The gradual decrease in peroxidase activity and the increase in polyphenol oxidase activity occurred in the case of fruit preservation by both methods. In the fruits storaged by the Fitomag method, the values of these enzymes were lower compared to those in the ordinary atmosphere. The lower intensity of the redox processes has beneficially influenced the preservation of the quality of the fruits preserved by this method compared to the usual atmosphere. There were also essential differences between the control and the variants treated with SBA Reglalg and microelements, as well as between varieties.

scholarly journals Effect of multilayer nylon packages on the oxidative damage of minimally processed yam

2019 ◽  
Vol 22 ◽  
Author(s):  
Adriano do Nascimento Simões ◽  
Daniel Gomes Coelho ◽  
Kelem Silva Fonseca ◽  
Aurélio Paes Barros Júnior ◽  
Sergio Luiz Ferreira-Silva ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Shelf Life ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Quality Loss ◽  
Minimally Processed ◽  
Polyphenol Oxidase Activity ◽  
Processed Products ◽  
Physiological And Biochemical

Abstract Appropriate storage packaging is an important aspect to minimize physiological deterioration and enhance the shelf-life of minimally processed products. Thus, the goal of this study was to evaluate the physiological and biochemical changes associated with the quality loss of minimally processed yam, maintained in two different packages at 5 ± 2 °C. The yam roots were selected, washed and conserved at 8 ± 2 °C for 24 hours. They were then peeled and cut into slices about 3 cm thick and minimally processed. Approximately 300 g of minimally processed yam roots were packed in polypropylene (PP, 4 μm thick) and multilayer nylon (NY, 15 μm thick) 15 cm wide x 20 cm long bags, which were stored at 5 ± 2 °C for 14 days. The minimally processed yam conserved in PP packaging presented fluorescence on the surface of the segments, characteristic symptoms of Pseudomonas spp., and showed higher peroxidase and catalase activities. The nylon packaging was more efficient in reducing oxidative damage and also inhibited polyphenol oxidase activity and decreased the accumulation of soluble proteins, resulting in decreased deterioration during storage. Thus, the quality of the minimally processed yam maintained in NY packaging was conserved for 14 days at 5 ± 2 °C.

scholarly journals Effect of antioxidants and pH on browning and firmness of minimally processed eggplant

2020 ◽  
Vol 48 (1) ◽  
pp. 79-89
Author(s):  
Diana P. USCANGA-SOSA ◽  
María B. PÉREZ-GAGO ◽  
Fernando C. GÓMEZ-MERINO ◽  
José A. HERRERA-CORREDOR ◽  
Aleida S. HERNÁNDEZ-CÁZARES ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Storage Period ◽  
Visual Quality ◽  
Minimally Processed ◽  
Polyphenol Oxidase Activity ◽  
Minimal Processing ◽  
Visual Evaluation

Minimal processing of eggplant (Solanum melongena L.) generates loss of firmness and polyphenol oxidase catalyzes the oxidation of phenolic compounds producing enzymatic browning. The aim of this study was to evaluate the effect of 1% ascorbic acid and 2% calcium ascorbate in aqueous solution at natural pH of the antioxidant (pH 2.6 and 7.8, respectively), or adjusted to pH 5 with generally recognized as safe substances, mantaining the quality of minimally processed eggplant stored at 5 °C for 6 d. Water was used as a control. The color, firmness, polyphenol oxidase activity, and visual quality was evaluated in the freshly cut fruit at 3 and 6 d of storage. No effect of the treatments on firmness or polyphenol oxidase activity was observed. At 3 d of storage, a correlation was observed between polyphenol oxidase activity and the visual evaluation of the cut product. Samples treated with 2% calcium ascorbate and the rest of the treatments at pH 5 had a lower browning index than those treated with 1% ascorbic acid and the control. At the end of the storage period, the visual quality of the eggplant samples treated with 1% ascorbic acid at pH 5 was evaluated above the marketing limit, whereas those treated with 1% ascorbic acid at pH 2.6 had the lowest quality indicators. An adjustment to pH 5 helps to preserve the luminosity and visual quality of the eggplant, however firmness was not affected by calcium ascorbate or the pH of the medium.

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