Research on efficiency of different sulphur dioxide generators on storability of fresh table sultana seedless grapes

This study was conducted to determine the effects of different sulphur dioxide (SO2) generators on quality and storability of fresh Sultana Seedless table grapes. Grapes were harvested at fully ripe stage from a vineyard in Sarıgöl township of Manisa province. The experiment was conducted as two groups. The first group of samples were packaged and enclosed with SmartPac packages that have different perforation ratio as a) SmartPac ‰0, b) SmartPac ‰0.5, c) SmartPac ‰1, and d) SmartPac ‰2. The second group of the samples were packed in polyethylene MAPs. After the precooling process, the SO2 pads were placed at different positions as a) above the grapes b) at the top and bottom and c) no SO2 pads as the control group and then closed. SmartPac, with SO2 pads above the grapes and top - bottom had 4.5 g, 6.5 g and 1.5 g and 6.5 g of SO2 respectively. Samples were stored at -0.5oC and 90% relative humidity for 120 days. During the storage period, SmartPac's SO2 content indicated a stable decrease and after 45 days there were no SO2 gas remaining in the packages. The samples that were placed with SO2 generating pads remained at SO2 concentrations ranging between 8 and 18 ppm during the storage. All trials limited the weight loss, significantly. Different SO2 generating pads showed similar effects on berry removal force, L*, a*, b* values, total soluble solids, titratable acidity, maturity index and pH. After 2 and 3 months of storage, decay development and stem browning became significant in the control group and SmartPac applications. The results showed that the Sultana Seedless grapes can be stored successfully for 2 months in SmartPac packages and 4 months in SO2 generating pads.