Effect of postharvest temperature on the muscat flavor and aroma volatile content in the berries of ‘Shine Muscat’ (Vitis labruscana Baily×V. vinifera L.)

The muscat flavor of table grapes often decreases after harvest, but the contributions of post-harvest temperature to the flavor loss were unknown. In the present study, the effect of different postharvest temperatures on muscat flavor and the content of aroma volatiles was investigated at 0, 2, 5, and 10°C for 12 weeks in the berries of ‘Shine Muscat’ (Vitis labruscana Baily× Vitis vinifera Vitis vinifera L.), which has a strong muscat flavor. Furthermore, after 2, 4, and 8 weeks of storage at 0°C, the grapes were subjected to post-storage conditioning at 10°C for 14 more days, and changes in the aroma volatile content were investigated. A sensory test showed that after 4 weeks of storage, the muscat flavor obviously decreased at 0°C, but at 10°C, the muscat flavor was maintained. Gas chromatography analysis of aroma volatiles showed that the content of linalool, which is one of the causative agents of muscat flavor, dramatically decreased at low temperatures (0, 2, and 5°C) in comparison with that at 10°C. During storage, the linalool content was much lower at 0°C than at 10°C in both the skin and the flesh. Interestingly, the linalool content, as well as muscat flavor, which decreased during storage at 0°C, increased after the grapes were subjected to post-storage conditioning at 10°C. The linalool content of the grape conditioned at 10°C for 1–14 more days was higher than that of the grape continuously stored at 0°C. These results indicated that muscat flavor is strongly influenced by postharvest temperature and that low-temperature storage enhances the loss of muscat flavor and the decrease in linalool content, but storage at 10°C delayed and minimized them. Moreover, these results showed that post-storage conditioning at an increased temperature before consumption would be effective to increase the muscat flavor even after flavor loss during low-temperature storage at 0°C.