Effect of postharvest pretreatments and MAP on phenolic compounds of organic late-season table grapes Scarlotta seedless® “Sugranineteen” assigned to medium and long term storage.

The consumer awareness of the beneficial health effects of organic grapes attributed to their valuable source of phenolic compounds, has increased in the recent years. Moreover, The high demand for fresh organic table grapes with perfect appearance and high nutritional quality is very challenging due to the restriction of sulphur dioxide (SO2) use on certified organic produce. In this context, the aim of the following experimental trial was to maintain the visual and nutritional qualities of organic table grapes for medium and long term storage by using safe methods as alternatives to SO2 application. Clusters of the organic late-season variety Scarlotta seedless® were pretreated with several concentrations of ozone (O3) and carbon dioxide (CO2), and compared to untreated control. All the processed samples were packed in thermo-sealed ALPAK commercial bags with 2% O2, 5% CO2, 93% N2 modified atmosphere packaging (MAP) and stored at 0°C for 45 days. The main quality parameters: weight loss, berr y color, phenolic compounds and sensory qualities, were evaluated immediately at harvest and after 15, 30 and 45 days under simulated shipping conditions. After 45 days, hue angle values were inversely correlated with Color Index for Red Grapes (CIRG), particularly higher in the control and lower in the sample treated with O3 at 20 ppm. The sensory quality was preserved with clusters pretreated with O3 at 20 ppm and control. Total anthocyanin contents increased in all samples assayed and the highest values wasregistered in samples pretreated with O3 at 10 ppm. Although, total flavonoids and polyphenol content was maintained in almost all samples. The results indicated that the alternative methods tested on red organic table grapes, maintained or slightly increased the antioxidant compounds content.