Heat treatment effects on ACC oxidase activity of 'Keitt' mangoes

Abstract

With the use of ethylene dibromide for mango disinfestation being ruled out, vapor heat or hot water treatments are the only alternatives for quarantine treatments of mangoes. Physical treatments such as heat treatments have been implicated in higher incidence of physiological disorders and enhancement of ripening processes. Therefore, the objective of the present work was to determine the effects of hot water treatments on ethylene production and on the in vitro activity of ACC oxidase. Cv. Keitt mangoes were immersed for 3 min in hot water at 53°C or 90 min in water at 46°C. Immediately after the treatments, some of the mangoes were analyzed for ACC oxidase activity and others were stored to be analyzed after 4 days at 12°C. There was a significant increase in the ACC oxidase activity just after the hot water treatments. After 4 days, only the mangoes treated for 90 min maintained high ethylene production and ACC oxidase activity. Tissue from the outer layers of the mesocarp had higher enzyme activity compared to tissues from the innermost layers of the mesocarp of heat-treated mangoes.