Effect of chitosan coating on some characteristics of mango (Mangifera indica L.) "Ataulfo" subjected to hydrothermal process

Because of the possible presence of immature stages of the Mexican fruit fly, Anastrepha ludens (Loew), the mango fruits cv. Ataulfo are most often treated by immersion in hot water (46.1°C during 90 min. This hydrothermal process has been shown to accelerate the ripening of fruit, but undesirable effect can be reversed with the use of coatings of various compositions. The objective for this study was to determine the effect of chitosan coating on physicochemical and biochemical parameters of Ataulfo mango subjected to hydrothermal process. Using mature green fruit, free from both physical and biological damage, the following treatments were established: 1) Fruits with hydrothermal process not coated with chitosan (HCh-), 2) fruits with hydrothermal process coated with chitosan (HCh+), 3) fruits without hydrothermal process not coated with chitosan (Ch-) and 4) fruits without hydrothermal process coated with chitosan (Ch+). All fruits were stored for 21 days at 22°C and 80 to 85% RH. At the end of their storage, fruits of HCh+ treatment had higher values of firmness, but weight loss, pH, PG and PME activity, production of CO2, tone and chromaticity, lower than those shown by the fruits of HCh- treatment. The results obtained in treatments Ch-and Ch+, together with those reported by other authors who used chitosan as a coating, suggests a hypothesis: that the attenuation in the physiology of the fruits are due to changes in gas transfer.   Key words: Gas transfer, postharvest quality, biocoating, ripening.