Journal of the Science of Food and Agriculture · 1998 · 49 citations · 0 references
AgricultureBiochemistryPlant SciencesBiocatalysisFood ChemistryPlant BiochemistryFruit BiochemistryOxidative Enzymes In FoodsActivation EnergyActivation Energy DeterminationExtractMichaelis ConstantPh DependencePolyphenol Oxidase ActivityPolyphenol Oxidase InactivationPolyphenol Oxidases
Polyphenol oxidase (PPO) activity of filtered extract of ground mango kernel suspension (400 g litre−1) was studied spectrophotometrically at 420 nm using catechol as substrate. The enzyme was most active at pH 6·0 and 25°C. Activity was reduced by 50% at pH values of 5·0 and 7·1, and also at temperatures of 14°C and 30°C. The calculated activation energy and the Michaelis constant (Km) were 21·4 kcal mol−1 °C−1 and 24·6 mM, respectively. The Vmax value was 2·14 units g−1 mango kernel. The time to heat inactivate PPO decreased rapidly to < 10 min with increasing temperature of ⩾ 70°C at 50% activity. © 1998 SCI.