Impact of Preharvest Foliar Application of Calcium Ascorbate on Quality, Health Promoting Phytochemicals and Postharvest Life of Thompson Seedless Table Grape

Table grapes are perishable crops with a high susceptibility to postharvest phytopathogens. Use of natural phytochemicals as elicitors for improving crop quality and enhancing the natural resistance against postharvest pathogens is a novel approach. Calcium ascorbate (CaAs) is an ecofriendly and inexpensive compound used as anti-browning agent in fresh cut fruits and minimally processed products. Thompson seedless table grapes (Vitis vinifera L.) were treated with calcium ascorbate (CaAs) at 0, 5% and 10% 48 h before harvest and stored for 60 days at 1 +/- 1 degrees C after harvest. CaAs of 5% significantly enhanced the berry total acids, total phenolics, flavonoids and carotenoids contents, and total antioxidant, ascorbate peroxidase, superoxide dismutase and catalase enzymes activities and decreased total soluble solids content, malondialdehyde, electrolyte leakage and pH. The treatment at both concentrations enhanced the berry firmness and decreased browning and color change indices at harvest time and during storage. After 2 months of storage, the highest ascorbate peroxidase activity, flavonoids and carotenoids contents was recorded in fruit treated with 10% CaAs, while the lowest decay extension rate, electrolyte leakage, weight loss, browning and color change was recorded in the berries treated with 5% CaAs. Furthermore, CaAs at 5% caused a significant decrease in weight loss and decreased berry abscission and decay extension rates during storage.