RESUMO
Muscadine grapes (Vitis rotundifolia Michx.) are delicate in nature with short shelf life. Postharvest technologies like modified atmosphere packaging (MAP) with reduced oxygen (O2) and elevated carbon dioxide (CO2) could increase the postharvest storage life with better quality. In the current experiment, physical and biochemical quality attributes of black and bronze cultivars of muscadine grapes ('Supreme' and 'Granny Val', respectively) were evaluated in active MAP. Fruit were packed in plastic trays, sealed with impermeable film, and CO2 was introduced into the package. The MAP was created by a rigid microperforated plastic patch coated with a proprietary semipermeable resin, which was applied over a hole in the tray; packages with the same size hole without a patch were the control. Fruit were stored at 4°C for 42 days (6 weeks). MAP resulted in significantly lower decay incidence and better retention of fruit firmness for up to 28 days of storage in both cultivars as well as reducing color changes in 'Supreme' fruit. Although MAP did not affect the biochemical quality of muscadine grapes, total antioxidants increased initially and then decreased during storage, irrespective of packaging treatments. A significant linear increase in total phenolic content was also found during storage, regardless of treatments applied. Overall, the results of the current study demonstrate that MAP can be an affective technology to increase storage duration of muscadines with better retention of physical quality, without affecting the biochemical attributes.
RESUMO
BACKGROUND: Achieving a larger berry size accompanied with even ripening are demanded by producers in growing muscadine cultivars. The current study aimed to evaluate the impact of fruit thinning on berry size and quality in two muscadine grape cultivars, 'Triumph' a bronze-fruited cultivar bearing hermaphrodite flowers, and 'Supreme' a dark black-fruited cultivar bearing female flowers. Thinning was performed before bunch closure and only one cluster per cane was retained. RESULTS: Results indicated a significant interaction of treatments and cultivars on berry weight and berry diameter. In 'Supreme,' berry weight and berry diameter were significantly increased where thinning was performed, and difference in plant yield between thinned and not thinned vines was not significant. For 'Triumph,' thinning had no significant impact on berry weight and diameter, but yield was ultimately reduced. Other physico-chemical characters were not affected by fruit thinning. However, differences were observed between both cultivars for these characters. The values of antioxidant scavenging activity (ASA) and total phenolic content (TPC) were 62.7% and 21.7% higher in 'Supreme' as compared to 'Triumph,' irrespective of the thinning treatments. Being a colored cultivar, 'Supreme' berries have higher anthocyanins than 'Triumph,' which has a negligible amount of anthocyanins. The ASA exhibited a strong positive correlation with TPC and anthocyanin content of muscadine grapes. There was also a significant positive correlation between TPC and anthocyanins. CONCLUSION: Cluster thinning of some muscadine grape cultivars may improve individual berry size without affecting overall plant yield or the fruit color, firmness, biochemical attributes and bioactive compounds. © 2023 Society of Chemical Industry.