Abstract:Vacuum freeze-drying effectively preserves the quality of jujube fruit. However, freeze-dried products are prone to quality deterioration, such as color deterioration, during shelf life. To mitigate the quality deterioration of freeze-dried jujube slices during their shelf life, Muzao was selected as the test material and pretreated with various concentrations of citric acid (CA), L-cysteine (L-Cys), and D-sodium erythorbate (D-SE). The sensory and entropy weight TOPSIS methods were used to comprehensively assess and identify high-quality groups by tracking changes in quality indices during shelf life. The results showed that compared with the CK group, 1.5% L-Cys and 1.0% CA were more effective in maintaining the quality of freeze-dried jujube slices. L-Cys pretreatment was better than CA pretreatment, with better maintained values of a* (-2.64) and b* (16.07), effective inhibition of PPO activity (6.45 U/g), and slow decrease of chlorophyll (1.39 mg/100 g), carotenoid (0.145 mg/100 g), and total phenol (417.28 mg/100 g) contents in freeze-dried jujube slices over 180 days of shelf life. In contrast, the 0.6% D-SE group demonstrated inferior performance in maintaining the quality of freeze-dried jujube slices during shelf life, with the a* value (-0.79) and PPO activity (14.90 U/g) significantly higher than those of the CK group. These findings suggest that 1.5% L-Cys pretreatment can effectively preserve the quality of freeze-dried jujube slices, delay quality deterioration during shelf life, and extend the shelf life to more than 210 days. These findings provide theoretical support for the high-value processing and utilization of jujube fruit, significantly contributing to the development of the jujube industry.
