Abstract:In order to investigate the impact of gradient warming on the quality preservation of the litchi stored at low temperature during shelf life, "August Red" litchi was selected as the experimental material. After 1 day of storage at 1 ℃, the litchi fruits were gradually brought back to room temperature (25 ℃) in three different temperature environments: 9, 18, and 25 ℃ , which was set as the "gradient rewarming" treatment group. Meanwhile, another group of litchi fruits stored at 1 ℃ for 1 d were directly placed in a room temperature environment (25 ℃) to restore to room temperature, which was set as the “direct rewarming” group as the control, to simulate the shelves placed under room temperature conditions for 0, 1, 3, and 5 d, respectively, and various indicators related to litchi fruit quality during the shelf life were measured. The results demonstrated that the "gradient rewarming" treatment effectively mitigated browning of litchi fruits. After the "gradient rewarming" treatment followed by standing at room temperature for five days, the browning coefficient of the “direct rewarming” litchi was 1.50, whilst the browning coefficient of the "gradient rewarming" litchi was only 1.00. In addition, "gradient rewarming" was found to delay the decreases in soluble solids content, titratable acids content, total phenols content, flavonoids content, and anthocyanins content, while also inhibiting effectively the increases in the activities of polyphenol oxidase and peroxidase in the peels. Therefore, the use of gradient rewarming treatment can effectively alleviate the quality deterioration of litchi stored at low temperature, extend litchi’s shelf life, indicating broad application prospects.
