Effect of Gamma Irradiation as Quarantine Treatment On Quality Mexican Mango Fruits

Mexico is the main exporter of mango to USA, with 45 million boxes exported during the 2009 season. To prevent the spread of Mexican fruit flies (Anastrepha ludens), the fruit with maturity at ¼ must be dipping in hot water (46.1C for 70-110 min depending on size fruit). This thermal stress modifies the ripening process and alters the sensory fruit quality and some varieties do not resist this treatment and they cannot be exported at that country. The USDA approved the application of gamma rays (0.15 kGy minimum and 1.0 kGy maximum) as alternative to hot water treatment; this procedure could be applied on mango fruit at ¾ maturity and at room temperature which could improve the sensory fruit quality. But the postharvest behavior is unknown in different mango varieties submitted at these doses. The aim of this study was to evaluate the physicochemical and visual quality of six mango varieties (‘Tommy Atkins’, ‘Haden’, ‘Kent’, ‘Keitt’, ‘Ataulfo’ and ‘Manila’) harvested at ¼ and ¾ maturity stages, submitted at 0, 0.15, 0.6 y 1.0 kGy and stored at 10 and 20°C during 19 days as well as in fruit transferred from 10 to 20°C for 6 days. At different periods the weight loss, firmness fruit, the skin and flesh color, titratable acidity, solids soluble content, ascorbic acid and visual quality were measured. As expected, the temperature affected significantly all response variables. All varieties in both maturity stages did not show external and internal damages when they were irradiated between 0.15 to 0.44 kGy but all varieties did present internal and external damages when they were irradiated between 0.92 to 1.52 kGy. The study suggested that the irradiation is not recommended in fruit of maturity ¼ being better irradiate fruits of maturity ¾. The maximum dose tolerated depended on the variety;  ‘Kent’ and ‘Ataulfo’ resisted to 0.86 kGy, while the varieties ‘Tommy Atkins’, ‘Haden’ ‘Manila’ and ‘Keitt’ showed visual damages at 0.6kGy. The physicochemical analysis data indicated that none of the variables can be an adequate indicator of the radiation effect because the responses depended on the variety, maturity stage and storage temperature.