Physiological and biochemical markers associated with quality losses of fresh-cut melon fruits

The fresh-cut melon (Cucumis melo L.) fruits have been becoming popular all around the world. The shelf life of cut fruits is usually limited to few days (4-5) if properly stored. In the frame work of the FP7 – QUAFETY project the melon has been used as model fruit for identifying physiological and biochemical parameters that can be associated with the quality losses of the fresh-cut fruits. Melon fruits, cultivar ‘Macigno’ were harvested in Mantova, Italy, under natural conditions. Within two hours from harvest the melons were peeled, cut in homogenous pieces and packed in plastic boxes simulating the fresh-cut procedures which are normally applied by the industry. Two storage temperatures were tested in order to simulate recommended storage (4 ºC) and abuse conditions (20 °C). We analyzed changes in ethylene (production and accumulation), ascorbic acid, lipid peroxidation and sugars (sucrose, reducing sugars and total sugars). Ethylene production and accumulation were higher at 20 °C but had the same trend at both storage temperatures. Ascorbic acid at harvest was 20 mg/100 g fresh weight (FW) and increased up to 25 mg/100 g FW during the first days of storage, then declined only at the end of storage (after 11 and 4 days at 4 and 20 °C respectively). Lipid peroxidation increased under both storage conditions reaching the highest levels after 7 days at 4 °C and after 3 days at 20 °C. Sucrose levels decreased during storage even though it showed an irregular pattern. Reducing sugars decreased rapidly after 1 day of storage and then remain stable in samples at 4 °C, while the decrement was more linear in samples stored at 20 °C. Total sugars remained quite constant at both temperatures and decreased in the last days of storage at 20 °C. From these preliminary results we can conclude that ethylene, lipid peroxidation and sugar content can be further studied as potential quality markers as they showed significant changes in response to storage temperature.