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Polyphenol oxidase is an enzyme found throughout the plant and animal kingdoms, [31] including most fruits and vegetables. [32] PPO has importance to the food industry because it catalyzes enzymatic browning when tissue is damaged from bruising, compression or indentations, making the produce less marketable and causing economic loss.
Chelating agents − Polyphenol oxidase requires copper as a cofactor for its functionality, thus copper-chelating agents inhibit the activity of this enzyme. Many agents possessing chelating activity have been studied and used in different fields of food industry, such as citric acid , sorbic acid , polyphosphates , hinokitiol , kojic acid ...
The main source of polyphenols is dietary, since they are found in a wide array of phytochemical-bearing foods.For example, honey; most legumes; fruits such as apples, blackberries, blueberries, cantaloupe, pomegranate, cherries, cranberries, grapes, pears, plums, raspberries, aronia berries, and strawberries (berries in general have high polyphenol content [5]) and vegetables such as broccoli ...
The glycosylated form develops from glucosyltransferase activity and increases the solubility of polyphenols. [47] Polyphenol oxidase (PPO) is an enzyme that catalyses the oxidation of o-diphenols to produce o-quinones. It is the rapid polymerisation of o-quinones to produce black, brown or red polyphenolic pigments that causes fruit browning ...
An oxidative enzyme is an enzyme that catalyses an oxidation reaction. Two most common types of oxidative enzymes are peroxidases, which use hydrogen peroxide, and oxidases, which use molecular oxygen. [1] [2] They increase the rate at which ATP is produced aerobically. Oxidative enzymes are responsible for the browning of fruits like apples.
The two copper atoms within the active site of tyrosinase enzymes interact with dioxygen to form a highly reactive chemical intermediate that then oxidizes the substrate. The activity of tyrosinase is similar to catechol oxidase, a related class of copper oxidase. Tyrosinases and catechol oxidases are collectively termed polyphenol oxidases.
Arctic Apples are a suite of trademarked [70] apples that contain a nonbrowning trait created by using gene silencing to reduce the expression of polyphenol oxidase (PPO). It is the first approved food product to use this technique. [71]
Natural phenols are a class of molecules found in abundance in plants. Many common foods contain rich sources of polyphenols which have antioxidant properties only in test tube studies. As interpreted by the Linus Pauling Institute, dietary polyphenols have little or no direct antioxidant food value following digestion. [7]