Inhibition of endive (Cichorium endivia L.) polyphenoloxidase by a Carica papaya latex preparation

Abstract

When endive polyphenoloxidase (PPO) was incubated with a crude papaya latex extract, it rapidly lost its activity. Inactivation was ascribed to thermostable nonenzymatic factors of low molecular weight. These factors were partially purified by a two step protocol including gel filtration chromatography on Biogel P2 and ion exchange chromatography using DEAE Sephadex A25. The PPO‐inactivation rate was first order, when either inactivating agent or proton concentration was evaluated. Inactivation could be partially reversed by CuSO4, which suggested that the inactivating factor(s) bound to the copper site of the enzyme. On a more rapid time scale than inactivation, papaya latex extract acted also as a weak noncompetitive PPO inhibitor.

Consumer acceptance and physicochemical quality of osmodehydrated carambola (Averrhoa carambola L.) slices

“…On convection drying of OD carambola slices, colour became less green (+ ‘a’) and more orange (lower h°). The browning of fruits and vegetables results from the oxidation of phenolic compounds catalysed by polyphenoloxidase (PPO) into quinones and their subsequent polymerization by both enzymatic and non‐enzymatic reactions 41 . Polyphenoloxidase was isolated and characterized in carambola 42 .…”

“…The browning of fruits and vegetables results from the oxidation of phenolic compounds catalysed by polyphenoloxidase (PPO) into quinones and their subsequent polymerization by both enzymatic and non-enzymatic reactions. 41 Polyphenoloxidase was isolated and characterized in carambola. 42 Blanching before osmotic dehydration was applied to inactivate enzymes, stabilize colour 43 and to soften the external texture of the fruit.…”

Colour and texture of apples high pressure processed in pineapple juice

“…Physiological and biochemical changes in such products occur at a faster rate than in intact fruits resulting in the rapid onset of enzymatic browning (Brecht, 1995;Buta & Abbott, 2000) and excessive tissue softening (Toivonen & DeEll, 2002). Enzymatic browning and the resultant discolouration of cut fruit products, upon exposure to air, is a major problem for the food industry impairing not only the colour of fresh-cut fruits but also the flavour and the nutritional quality (Rigal, Cerny, Richard-Forget & Varoquaux, 2001). Mainly the browning is developed due to enzymatic oxidation of phenols to quinones by polyphenoloxidase (PPO) in the presence of oxygen.…”

Biochemical Characterization of Banana Cultivars From Southern India

“…Enzymes such as Polyphenol oxidase (PPO) have also been found to be important in improving the quality and shelf life of bananas. The enzymatic browning impairs not only the color of fresh fruits but also the flavor and the nutritional quality (Rigal et al, 2001). Besides these major constituents, banana phenols, flavones, and some mineral elements also play a major role in human nutrition.…”