Effect of refrigerated storage on Manila mangoes (Mangifera indica L.) after hydrothermal treatment

Mangoes (cv. Manila) were subjected to the USDA-approved hydrothermal disinfestation treatment and subsequently stored at 6 or 12 C. Quality parameters were monitored during refrigerated storage and subsequent ripening at 25 C. Both treated and untreated mangoes displayed similar patterns of ripening in terms of changes in textural hardness, titratable acidity, reducing sugars, soluble solids and respiration rate, as well as sensory parameters. The first symptoms of chilling injury were detected in mangoes stored at 6 C for 16 days and allowed to ripen at 25 C for 7 days. Mangoes stored at 12 C displayed the first symptoms after 20 days and 5 days of ripening. Appearance of chilling injury correlated with elevated respiration rates at 25 C after prior refrigeration treatments. Visually, the disorder was characterized by brown discoloration areas within the pericarp, and uneven ripening and color changes in the mesocarp region close to the seed. These symptoms appeared after the chilling stress and during ripening at 25 C. Fruits exposed to 6 C were also subject to pulp browning which increased as the period of chilling stress was extended, and became pronounced in fruits held at 6 C for 24 days. Sensory evaluation of mangoes stored at both chilling temperatures showed no differences when the external portion of the mesocarp of visibly sound fruits were evaluated. It was concluded that the hydrothermal treatment did not alter the ripening patterns and susceptibility to chilling injury of mangoes. Increases in respiratory activity appeared to be a potential index for monitoring the progress of chilling injury in mangoes subject to the treatments described in this study.