Activity of polyphenoloxidase and peroxidase in non-dormant potato tubers treated with sprout suppressors

One of the major problems affecting potatoes quality on stored is the susceptibility to enzymatic browning, which occurs mainly after wounds during the harvest, at postharvest handling and by aging, leading to the development of dark color compounds. Enzymatic browning is associated with the action of polyphenoloxidases (PPO) and peroxidases (POD), which use phenolic compounds and oxygen as substrates. The products of these enzymes cause undesirable changes of color and flavor of processed potato products. The present study aimed to evaluate some kinetic properties based to optimum pH and reaction temperature, and to determine changes on activity of potato tubers PPO and POD treated with sprouting suppressors compounds menthol and eugenol. For each treatment, samples were collected in six different periods, before application (day 0) and 10, 20, 30, 40, and 50 days after the treatments to determine the influence of sprout inhibitors on the activity of PPO and POD. Changes in pH and temperature affected drastically the activity of both enzymes. The use of eugenol and menthol as sprouting suppressors decreased enzymatic activity on the treated tubers compared to control with an inverse relationship between enzymes activity and content of phenolic compounds.