Effect of harvest time and storage duration on some biochemical attributes of table grape cv  Bidaneh Sefid'

Evaluation of quality and biochemical indices during ripening is necessary to achieve high quality and extend fruit postharvest life. In this study, the effect of harvest time on the some quality attributes of table grape cv. ‘Bidaneh Sefide’ was investigated during two months storage at temperature of 1±0.5 °C and in 90-95% relative humidity. The study was conducted as a factorial experiment based on completely randomized design with four replicates. The fruits were harvested from a commercial Vineyard in Urmia, at three different maturity stages from 4 September to 29 September. Total soluble solids content, titratable acidity, vitamin C, total phenolics content, total antioxidant content, polyphenol oxidase and catalase enzymes activity were evaluated at harvest times and 20 days intervals during storage for two months. The results showed that by delay in harvest time, TSS increased but total acidity decreased. Total phenolics content and vitamin C increased with delay in harvest time but decreased during storage period. The activity of polyphenol oxidase significantly increased with delay in harvest time but first decreased and then increased during storage. The total antioxidant activity showed no change during ripening but it was affected by storage time. During storage, the activity of catalase enzyme was decreased. According to the results of this study, most of qualitative attributes in ‘Bidaneh Sefid’ table grape fruit is preserved for 40 days storage without any chemical treatment.