ABSTRACT Enzymatic browning is a biochemical process catalyzed by polyphenol oxidase (PPO), employing endogenous phenolic compounds and molecular oxygen as substrates. This intriguing reaction leads to the formation of brown or black pigments, commonly referred to as melanins, specifically occurring on the surfaces of certain fruits and vegetables. This research focuses on investigating the kinetic parameters of PPO, also known as tyrosinase, extracted from Agaricus bisporus (Paris mushroom) and Terfezia leonis (Desert truffle). The study explores the effects of pH, temperature, and substrate concentration (L-tyrosine) on PPO activity from both sources. The results demonstrate that the activity of PPO from Agaricus bisporus reaches its maximum at pH 5 and a temperature of 45 °C, with inhibition observed in the presence of excess substrate. The kinetic parameters, Vmax and Km, for Agaricus bisporus PPO were determined to be 0.07587 ΔAbs.Min^(-1) and 0.1386 mmol.l^(-1), respectively. On the other hand, the activity of PPO from Terfezia leonis reaches its peak at pH 5 and a temperature of 40 °C, and the corresponding kinetic parameters are Vmax = 66.35 μM/min and Km = 0.17 mM. Enzymatic browning has been a subject of interest for numerous scientists who have explored various techniques to inhibit or eliminate the compounds responsible for the reaction, such as oxygen, copper, substrate, or the enzyme itself. Overall, this study provides valuable insights into the kinetic behavior of PPO from Agaricus bisporus and Terfezia leonis, shedding light on potential strategies for inhibiting enzymatic browning to preserve the visual appeal and quality of food.
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