Alternatives to SO2 to maintain phenolic compounds and overall quality of ready-to-eat table grapes during long-term storage

This study aimed to evaluate the effects of ethanol, hot water, and 1-methylcyclopropene (1-MCP) as alternatives to sulphur dioxide (SO2) on the quality maintenance of ready-to-eat ‘BRS Nubia’, ‘BRS Isis’, and ‘Italia’ table grapes during storage. The treatments were: [1] control (only detached berries); [2] SO2 (1.5 g Na2S2O5 kg−1 grape); [3] ethanol (solution of 30% for 5 min); [4] hot water (50°C for 10 min) and; [5] 1-MCP (2.0 μL L−1 for 24 h). Table grapes were stored in vented polyethylene clamshells, allocated in experimental chambers during 30 and 60 days of storage (0.5°C). 1-MCP treatment did not reduce the table grape senescence during storage. Hot water and ethanol immersions showed similar or superior results to SO2 in decay control until 30 days, but after 60 days of storage, only ethanol and SO2 controlled decay incidence. However, hot water and ethanol increased the cracking incidence in ‘BRS Isis’ grapes. The phenolic content did not change between storage periods in ‘Italia’ grapes, while it decreased in ‘BRS Nubia’ and ‘BRS Isis’. Hot water treatment, and especially ethanol, can be used as alternatives to SO2 treatment to extend the shelf-life of ready-to-eat table grapes stored for long periods.