Abstract:Vacuum freeze-drying can better maintain the quality characteristics of jujube fruits. However, freeze-dried products are prone to quality deterioration such as color deterioration during shelf life. In order to reduce the quality deterioration of freeze-dried jujube slices during shelf life, Muzao was used as the experimental material, and different concentrations of citric acid (CA), L-Cysteine (L-Cys) and D-Sodium Erythorbate (D-SE) were used for pretreatment. Sensory and entropy weight TOPSIS methods were used to comprehensively evaluate and screen high-quality groups. Track the change of quality index during shelf life. The results showed that compared with the CK group, the 1.5% L-Cys and 1.0% CA group could better maintain the quality of freeze-dried jujube slices. It effectively inhibited PPO activity (6.45 U/g) and delayed the decrease of chlorophyll (1.39 mg/100 g) within 180 days, carotenoid (0.145 mg/100 g) and total phenol (417.28 mg/100 g) in freeze-dried jujube slices during shelf life. The effect of 0.6% D-SE group on maintaining the quality of freeze-dried jujube slices during shelf life was poor, a* (-0.79) and PPO activity (14.90 U/g) were significantly higher than that of CK group. It can be seen that 1.5% L-Cys pretreatment can effectively maintain the quality characteristics of freeze-dried jujube slices, delay the quality deterioration of freeze-dried jujube slices during shelf life and extend the shelf life to 210 days later. The results of this study provide theoretical support for the high-value processing and utilization of jujube fruit, which is of great significance for promoting the development of jujube industry.
