Physiological, metabolite and volatile analysis of cut size in melon during postharvest storage

Melons are an important component of fresh fruit salads, however, they suffer from limited shelf life. Processing of melon fruit for use in fruit salads induces a number of changes including alterations in colour and texture. In addition, respiration rate and ethylene production are affected. Processing also elicits changes in flavour (sweetness) and aroma (production of volatile organic compounds - VOCs), of critical importance to the consumer. Several parameters govern shelf life; temperature is a critical factor. In this study we tested whether cut size is another parameter that can affect quality indicators. Melon (Cucumis melo 'Arapaho') cubes of three sizes were stored at 4°C and assessed for quality at five time-points over a 15-day period. We assessed a number of parameters including firmness, loss of fresh weight, respiration rate, antioxidant capacity, phenolic compounds and carotenoid content. In addition we measured VOC profiles to assess whether there were any qualitative changes associated with storage period and/or cut size. Fresh weight (FW) loss and respiration rate increased significantly with storage time and FW loss was affected by cut size. Total carotenoid levels remained stable during the storage time as did antioxidant capacity in all cut sizes. However, cinnamic acid levels tended to decrease in the last stage of the storage period and changes in β-carotene content correlated with cut size (though not significantly). We were also able to separate the VOC profiles from the different cut sizes indicating that VOCs may be useful markers as indicators of the effects of cut size and storage time on quality.