Relationship between the Polyphenol Oxidase Activity of Coffee Beans and the Quality of the Beverage

Nature ◽  
1968 ◽  
Vol 219 (5152) ◽  
pp. 381-382 ◽  
Author(s):  
H. V. DE AMORIM ◽  
D. M. SILVA
Keyword(s):  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Polyphenol Oxidase Activity ◽  
Coffee Beans

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.

scholarly journals Comparison between Hyperspectral Imaging and Chemical Analysis of Polyphenol Oxidase Activity on Fresh-Cut Apple Slices

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Luna Shrestha ◽  
Boris Kulig ◽  
Roberto Moscetti ◽  
Riccardo Massantini ◽  
Elke Pawelzik ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Hyperspectral Imaging ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Polyphenol Oxidase Activity ◽  
Robust Detection ◽  
Deming Regression ◽  
Apple Slices ◽  
Fresh Cut

The assessment of the quality of fresh-cut apple slices is important for processing, storage, market value, and consumption. Determination of polyphenol oxidase activity (PPO) in apples is critical for controlling the quality of the final product (i.e., dried apples and juices). Hyperspectral imaging (HSI) is a nondestructive, noncontact, and rapid food quality assessment technique. It has the potential to detect physical and chemical quality attributes of foods such as PPO of apple. The aim of this study was to investigate the suitability of HSI in the visible and near-infrared (VIS-NIR) range for indirect assessment of PPO activity of fresh-cut apple slices. Apple slices of two cultivars (cv. Golden Delicious and Elstar) were used to build a robust detection algorithm, which is independent of cultivars and applied treatments. Partial least squares (PLS) regression using the 7-fold cross-validation method and method comparison analysis (Bland–Altman plot, Passing–Bablok regression, and Deming regression) were performed. The 95% confidence interval (CI) bands for the Bland–Altman analysis between the methods were −4.19 and 13.11, and the mean difference was 3.7e−12. The Passing–Bablok regression had a slope of 0.8 and an intercept of 7.6. The slope of the Deming regression was 0.8 within the CI bands of 0.56 and 1.10. These results show acceptable performance and no significant deviation from linearity. Hence, the results demonstrated the feasibility of HSI as an indirect alternative to the standard chemical analysis of PPO enzyme activity.

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