scholarly journals Enzymic browning of apples by polyphenol oxidases

2000 ◽  
Vol 18 (No. 6) ◽  
pp. 213-218 ◽  
Author(s):  
J. Lachman ◽  
V. Pivec ◽  
M. Orsák ◽  
J. Kučera
Keyword(s):  
Polyphenol Oxidases ◽  
Enzymic Browning

scholarly journals Antioxidant complex of bioflavonoids and ascorbic acid in apples (Malus pumila Mill.) – a review

2000 ◽  
Vol 18 (No. 4) ◽  
pp. 153-158
Author(s):  
J. Lachman ◽  
M. Orsák ◽  
V. Pivec
Keyword(s):  
Ascorbic Acid ◽  
Malus Pumila ◽  
Polyphenol Content ◽  
Intrinsic Factors ◽  
Polyphenol Oxidases ◽  
Apparent Decrease ◽  
Deterioration Process ◽  
Malus Pumila Mill ◽  
Enzymic Browning ◽  
Apple Fruits

In this review article it is given an information about the composition of flavonoid complex of apples (Malus pumila Mill.). It is discussed the influence of extrinsic and intrinsic factors on polyphenolic antioxidant content (varietal differences, influence of locality, year, maturity, pre-harvest treatment, storage, technological ways of processing) and the relation between the polyphenol content and the resistance of apple varieties. During storage there is an apparent decrease of both ascorbic acid and polyphenols. Contents of anthocyanins and chalcones are in positive correlation with resistance of apple trees to low and variable temperatures. During maturation of apple fruits synthesis and accumulation of polyphenols, esp. anthocyanins, and ascorbic acid was determined. Meanwhile polyphenols are substrates of polyphenol oxidases in the process of enzymic browning, ascorbic acid is a natural inhibitor of this browning deterioration. Process of enzymic browning of apple fruits and juices could be inhibited with ascorbic and citric acid addition to apple products. Polyphenol content could be influenced by pre-harvest and technological procedures.

Chlorogenic Acid and the Enzymic Browning of Apples and Pears

Nature ◽  
1953 ◽  
Vol 172 (4380) ◽  
pp. 678-678 ◽  
Author(s):  
C. WEURMAN ◽  
T. SWAIN
Keyword(s):  
Chlorogenic Acid ◽  
Enzymic Browning

Regurgitant Derived From the Tea Geometrid Ectropis obliqua Suppresses Wound-Induced Polyphenol Oxidases Activity in Tea Plants

2013 ◽  
Vol 39 (6) ◽  
pp. 744-751 ◽  
Author(s):  
Zi-Wei Yang ◽  
Xiao-Na Duan ◽  
Shan Jin ◽  
Xi-Wang Li ◽  
Zong-Mao Chen ◽  
...  
Keyword(s):  
Polyphenol Oxidases ◽  
Tea Plants

scholarly journals Versatile Fungal Polyphenol Oxidase with Chlorophenol Bioremediation Potential: Characterization and Protein Engineering

2018 ◽  
Vol 84 (23) ◽  
Author(s):  
Efstratios Nikolaivits ◽  
Maria Dimarogona ◽  
Ioanna Karagiannaki ◽  
Angelina Chalima ◽  
Ayelet Fishman ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Fruits And Vegetables ◽  
Homology Model ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Gene Encoding ◽  
Content Type ◽  
Polyphenol Oxidases ◽  
Increased Activity ◽  
Work Knowledge

ABSTRACTPolyphenol oxidases (PPOs) have been mostly associated with the undesirable postharvest browning in fruits and vegetables and have implications in human melanogenesis. Nonetheless, they are considered useful biocatalysts in the food, pharmaceutical, and cosmetic industries. The aim of the present work was to characterize a novel PPO and explore its potential as a bioremediation agent. A gene encoding an extracellular tyrosinase-like enzyme was amplified from the genome ofThermothelomyces thermophilaand expressed inPichia pastoris. The recombinant enzyme (TtPPO) was purified and biochemically characterized. Its production reached 40 mg/liter, and it appeared to be a glycosylated and N-terminally processed protein.TtPPO showed broad substrate specificity, as it could oxidize 28/30 compounds tested, including polyphenols, substituted phenols, catechols, and methoxyphenols. Its optimum temperature was 65°C, with a half-life of 18.3 h at 50°C, while its optimum pH was 7.5. The homology model ofTtPPO was constructed, and site-directed mutagenesis was performed in order to increase its activity on mono- and dichlorophenols (di-CPs). The G292N/Y296V variant ofTtPPO 5.3-fold increased activity on 3,5-dichlorophenol (3,5-diCP) compared to the wild type.IMPORTANCEA novel fungal PPO was heterologously expressed and biochemically characterized. Construction of single and double mutants led to the generation of variants with altered specificity against CPs. Through this work, knowledge is gained regarding the effect of mutations on the substrate specificity of PPOs. This work also demonstrates that more potent biocatalysts for the bioremediation of harmful CPs can be developed by applying site-directed mutagenesis.

Latent Polyphenol Oxidases from Sago Log (Metroxylon sagu):  Partial Purification, Activation, and Some Properties

2000 ◽  
Vol 48 (10) ◽  
pp. 5041-5045 ◽  
Author(s):  
Galila Hassan Onsa ◽  
Nazamid bin Saari ◽  
Jinap Selamat ◽  
Jamilah Bakar
Keyword(s):  
Partial Purification ◽  
Polyphenol Oxidases ◽  
Metroxylon Sagu
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