Journal ArticleDOI
Apple Polyphenol Oxidase Activity in Relation to Various Phenolic Compounds
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The role of various polyphenolic compounds in oxidations catalyzed by apple polyphenol oxidase (PPO) was investigated in this paper, and it was hypothesized that the conjugated system in flavones prevents these compounds from being apple PPO substrates.Abstract:
SUMMARY— The role of various polyphenolic compounds in oxidations catalyzed by apple polyphenol oxidase (PPO) was investigated. Quercetin, quercitrin, rutin, cyanidin chloride, phloroglucinol, and resorcinol were neither substrates nor inhibitors of apple PPO. Phloroglucinol and resorcinol increased the rate of PPO catalyzed oxidation of chlorogenic acid.
Esculetin and dihydroquercetin were found to be substrates of PPO. No synergistic effect was detected in the browning rates of an esculetinchlorogenic acid mixture or a dihydroquercetin-chlorogenic acid mixture. Ferulic acid, fisetin, and p-coumaric acid were generally non-competitive inhibitors, although ferulic acid inhibited competitively in one test. It was hypothesized that the conjugated system in flavones prevents these compounds from being apple PPO substrates.read more
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Phenolics in food and nutraceuticals
Fereidoon Shahidi,Marian Naczk +1 more
TL;DR: Phenolics in Food and Nutraceuticals as mentioned in this paper is the first single-source compendium of essential information concerning food phenolics, which reports the classification and nomenclature of phenolics and their occurrence in food and nutraceuticals.
Journal ArticleDOI
Enzymatic browning reactions in apple and apple products
TL;DR: This review examines the parameters of enzymatic browning in apple and apple products that is, phenolic compounds, polyphenoloxidases, and other factors (ascorbic acid and peroxidase) both qualitatively and quantitatively.
Journal ArticleDOI
Inhibition of enzymatic browning in foods and beverages
TL;DR: Recent advances in the development of nonsulfite inhibitors of enzymatic browning are reviewed and the review focuses on compositions that are of practical relevance to food use.
Journal ArticleDOI
The role of intramuscular connective tissue in meat texture.
TL;DR: The structure, composition and amount of intramuscular connective tissue (IMCT) vary tremendously between muscles, species and breeds, and certainly contribute to meat texture, and further elucidations of molecular mechanisms which change the structural integrity of IMCT during chronological ageing of animals and postmortem ageing of meat are needed.
Journal ArticleDOI
Characterization of Polyphenoloxidase from Stanley Plums
TL;DR: Five plum cultivars were investigated for polyphenoloxidase, and Stanley cultivar, which showed highest PPO activity, was selected for characterization of this enzyme, which was strongly inhibited by sodium metabisulfite, L-cysteine and ascorbic acid.
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Journal ArticleDOI
Chlorogenic Acid and the Enzymic Browning of Apples and Pears
C. Weurman,T. Swain +1 more
TL;DR: Chlorogenic acid is known to be acted on by the polyphenoloxidase of sweet potatoes, and to be widely distributed in many plant tissues including apples and pears, and its role in the enzymic browning of these two fruits is investigated.
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Detection and identification of polyphenoloxidase substrates in apple and pear skins.
TL;DR: A paper chromatographic technique for the detection and identification of substances susceptible to darkening with polyphenoloxidase is described, finding the principal browning substrate on chromatograms of the skin extract from Grimes Golden and Golden Delicious apple and Bartlett pear was l -epicatechin.
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