Gradient Warming After Low-Temperature Storage Extends Shelf Life and Maintains Fruit Quality of Korla fragrant pears

In the postharvest supply chain, directly moving Korla fragrant pears from ice temperature storage to ambient display readily induces quality deterioration, shortens shelf life, and causes substantial economic losses. Using Korla fragrant pears as the study system, we propose a gradual rewarming protocol. We optimised temperature and time parameters with response surface methodology and validated the protocol by comparing changes in shelf-life quality and microstructure under gradual versus direct rewarming. Results indicate that rewarming at 6 °C for 12 h is the optimal condition for maintaining overall postharvest quality. Under these conditions, gradient rewarming significantly improved physical and chemical quality. Compared with direct rewarming, weight loss decreased by 2.6 percent, firmness increased to 4.23 kg/cm2, the peak soluble solids content reached 12.5%, the respiratory peak was delayed and the rate slowed, and shelf life was extended by about 80%. Microstructural verification showed a more compact cellular arrangement, reduced intercellular spaces, and the mildest degree of cell collapse in pears subjected to gradient rewarming. The proposed gradient rewarming protocol provides theoretical and practical guidance for optimising temperature control strategies across the postharvest cold chain and retail stages for Korla fragrant pears.