Biochemical changes and peroxidase activity during development of acerola Okinawa

ABSTRACT In this study, chemical changes during the development of acerola, cultivar Okinawa, were evaluated. The biochemical alterations during the development of the acerola cultivar Okinawa were evaluated, to determine the peroxidase activity (POD) and its thermal stability. Peroxidase (POD) has been considered the main enzyme responsible for the quality deterioration of fruits. Additionally, characteristics evaluated in this study can be important postharvest quality criteria for fruit processing, screening and breeding. Changes in physiological development were evaluated by the determination of moisture content, ascorbic acid, ashes, total and reducing sugars, pectin, chlorophyll a and b, amounts of anthocyanins, flavonols and total carotenoids. These biochemical determinations may serve as a basis for further improvement of techniques for predicting and modeling the optimal harvesting time. The values of chlorophylls, anthocyanins, flavonols, and carotenoids were higher in the peel rather than in the pulp (p < 0.05). Acerola presents high levels of ascorbic acid. The development of acerola (from opening of flowers to maturation of fruits) was of 25 days. The increase of the values for total and reducing sugars, anthocyanins, carotenoids, the solubilization of pectic acid and degradation of chlorophyll suggested that physiological maturation and harvest day occurred on days 19 and 23 after anthesis, respectively. The specific activity of POD was higher in the green stage. Maximum POD activity was observed at pH 6.5 and 45 ºC. Total inactivation was not achieved, suggesting the presence of isoenzymes with high thermal resistance. A loss of 50% of activity occurred after 4 minutes of treatment at 80 °C.