Effect of quarantine heat treatment on quality and postharvest physiology of papaya

Abstract

The postharvest heat treatment is applied in fruits in order to control diseases and insects. However, the fruit that is undergoing this treatment may have lower organoleptic quality and shows physical, chemical, physiological and biochemical changes. Thus, the project aims to study the physiology and postharvest of papaya and mango after application of the hydrothermal treatment, as well as the treatment influence on biochemical and quality of these fruits. It will be used Golden papayas and Tommy Atkins mangoes, in the maturity stage based on the skin and pulp colors, as exporters' standardization. The papayas will be subjected to hydrothermal treatment at 48 ºC for 20 min, followed by immersion in cold water at 8 ºC for 20 min. The mangoes will be subjected to hydrothermal treatment at 46.1 °C for 75 or 90 min, depending on the fruit weight, followed by immersion in cold water at 21 °C for 30 min. Fruits without the hydrothermal treatment will be used as control in all experiments. Mangoes and papayas are stored in chambers at 22 °C and 85% RH until complete ripening and/or senescence. In a second experiment, mangoes and papayas will be subjected to hydrothermal treatment described above and stored at 11 ºC and 85% RH during 20 days, simulating the export shipping. Then, the fruits will be stored at 22 °C until complete ripening and/or senescence. Both fruits will be evaluated on alternate days for respiration, ethylene production, enzyme activity, volatile compounds, weight loss, pulp external and internal firmness, pulp and skin color; and on every two days for soluble solids, ascorbic acid, pigments, decay, shriveling and chilling injury. Furthermore, the fruits will be analyzed for the amount of absorbed water at the end of the hydrothermal treatment and papayas will be evaluated for CO2 and ethylene endogenous concentrations during and shortly after the hydrothermal treatment. The experiments will be repeated twice and the experimental design will be completely randomized. For all analyzes will be used five replicates per treatment, being each repetition consists by one fruit. The results will be submitted to variance analysis and mean comparison test at 5% of probability. The physiological and biochemical changes observed after postharvest hydrothermal treatment will help us to understand how the ripening and senescence processes occur, are regulated and influenced. (AU)