Research on changes in postharvest physiology and fruit quality of Actinidia chinensis ‘Donghong’ under different storage methods

Changes in the postharvest physiology and fruit quality of ‘Donghong’, a novel red-fleshed kiwifruit cultivar of Actinidia chinensis Planch., under ambient and cold storage were investigated to provide theoretical and technical guidelines for fruit preservation and marketing. ‘Donghong’ fruits from an orchard in Pujiang county, Sichuan Province, were collected and stored at ambient (20℃±1℃, relative humidity 70%-75%) and cold temperatures (1.5℃ ±0.5℃, relative humidity 90%-95%). The main physiological indices of the fruit, including fruit firmness, soluble solids content (SSC), total sugar (TS) content, titratable acidity (TA) content, SSC/TA and TS/TA ratios, vitamin C (Vc) content, weight loss rate, and rot rate, were measured once a week under ambient storage and every three weeks under cold storage. Results indicated that during both ambient and cold storage, fruit firmness dropped rapidly during the first three weeks and nine weeks of ambient and cold storage, respectively, then slowed down slightly until the end of storage. Four physiological indices, including SSC, TS content, and SSC/TA and TS/TA ratios, showed similar patterns during both ambient and cold storage, first increasing sharply and then maintaining a highly stable level during cold storage or continuing to rise slightly during ambient storage. TA showed a gradual decrease from 1.12% to 0.92% during ambient storage and from 1.12% to 0.94% during cold storage. Vc content gradually increased and reached a maximum of 134.40 mg/100 g after five weeks of ambient storage, or generally increased at first, then declined slightly, and finally reached a maximum of 151.13 mg/100 g after 18 weeks of cold storage. Both the weight loss and rot rates gradually increased with storage length under both temperatures, with a rapid increase under ambient storage and extremely slow increase under cold storage. Both indices reached a maximum level of 16.09% and 20% after 33 weeks of cold storage, respectively. The main physiological indices of the ‘Donghong’ fruit exhibited obvious changes in trends after three weeks of ambient storage and nine weeks of cold storage, respectively, after which the fruits reached optimal edibility. Moreover, the ‘Donghong’ fruit largely maintained a high quality, with a very low rate of fruit rot and rarely lignified flesh during the first 24 weeks of cold storage, revealing outstanding storability.