Effect of harvest maturities on phytochemical composition of golden kiwifruit grown under South African conditions

The kiwifruit industry is becoming one of the most important in South Africa and the fruit is well known for its nutritional benefits, including antioxidants, ascorbic acid (vitamin C), sugar, and some phytochemical compounds. The amount of nutrients and phytochemicals in kiwifruit are greatly affected by maturity stage at harvest. The shortage of knowledge on the optimum maturity stage for harvesting for South African cultivars results in mixed harvesting and loss of postharvest quality. The purpose of this study was to investigate the effect of harvest maturity stage (early, mid and late) on phytochemical compounds of the fruit. Two cultivars ('Soreli' and 'Y368') were harvested from an orchard in Richmond (KwaZulu-Natal), South Africa. Each harvest consisted of 50 fruit. Each cultivar was arranged into boxes, with 4 replications per box. Fruit were stored in cold storage at 0°C for 2 months and after storage fruit left to ambient conditions for 7 days for shelf-life study. Fruits were sampled at harvest, after cold storage and end of shelf life for antioxidants, total phenolic compounds, ascorbic acid concentration and total soluble solids. The experimental design used in the study was randomised complete design. Harvest maturity had a significant effect on the investigated parameters for 'Soreli'. 'Y638' had the highest ascorbic acid concentration for mid and late maturity stage harvesting and 0°C storage than fruit harvest at an early maturity stage. Early harvested fruits resulted in poor fruit quality for 'Y368'. Mid and late harvested fruits stored at 0°C resulted in an improved phytochemical composition.