Changes of sugars, β-carotene and firmness of refrigerated Ataulfo mangoes treated with exogenous ethylene

The export of Ataulfo mangoes to the US market involves a mandatory hot wetter treatment and further handling at 13 C for 4 days. These treatments have proven to adversely affect fruit ripening, mainly in colour and flavour development, and their nutritional quality. The application of exogenous ethylene (100 mu l/l of air for 12 h at 25 C) to Ataulfo mangoes that were treated with hot water after storage for 4 days at 13 degrees C, and then transferred to 25 degrees C for ripening, was evaluated. Sugar content, colour development and textural firmness were monitored. Control fruit were held at 25 degrees C with no previous refrigeration or ethylene exposure; another batch was kept refrigerated for 4 days at 13 degrees C, not treated with ethylene and ripened at 25 degrees C. Synthesis of fructose (30 g/kg fresh weight (FW)), glucose (38 g/kg FW), sucrose (120 g/kg FW) and beta-carotene (0026 g/kg FW) in the last day of storage was greater in fruits treated with ethylene than on refrigerated mangoes (RM). Loss of firmness (9.3 Newtons) coincided with the highest pectinmethylesterase and polygalacturonase activities, 5324 and 3792 U/mg protein, respectively, and eventually led to collapse of cell structure. Results suggest that sugars and carotenoid content can be increased, along with an accelerated ripening by application of exogenous ethylene on mangoes that were refrigerated for 4 days.