High CO2-modified atmosphere to preserve sensory and nutritional quality of organic table grape (cv Italia) during storage and shelf-life

Table grape is a non-climacteric fruit subject to serious water and quality loss during postharvest handling. Gentle handling, careful bunch cleaning, fast cooling, low temperature, and sulfur dioxide (SO2) pad application during storage are generally used to improve storage. In this study, the effect of cold storage in modified atmosphere (MA) in different CO2 concentrations (0-20%) on the quality evaluated after a shelf-life period at ambient temperature, was studied. Organic table grape bunches (cv Italia), were packaged in MA bags and stored at 2 °C (± 1.0) for 14 days, using MA with 0% (air), 10% and 20% initial CO2 concentrations. Unpacked samples were used as control. The gas composition inside packages was periodically measured. After 7 and 14 days, all packages were opened and transferred in air at 20 °C for 3 days: sensory, physical and chemical-nutritional parameters were measured. A significant effect of high CO2 atmosphere on delaying visual quality and decay was shown. The best results in terms of preservation of sensory as well as nutritional quality were obtained using a 10% CO2 as initial concentration. Actually, this treatment was able to ensure a suitable atmosphere composition during all storage period: the O2 and CO2 concentrations after 14 days of MA storage, were found to be about 7% and 15%, respectively, i.e. a CO2 level enough to control the decay development and an O2 concentration sufficiently far from the anoxia threshold, as detected by acetaldehyde and ethanol measurement.