Analysis of Physicochemical Properties of Wendan Pomelo Enzyme Prepared Based on Yeast Fermentation

In order to explore the effect of yeast inoculation on the enzyme of Wendan pomelo, and analyze the dynamic changes of key physical and chemical indexes and the number of effective viable bacteria during the fermentation, the cracking fruit of Wendan pomelo was used as the raw material, and the natural fermentation group was taken as the control group. Then, the yeast inoculated fermentation experimental group was set up for the comparative test, and the changes of the metabolites such as the effective viable count, pH, organic acid, total phenol, and protease during the fermentation process of inoculated yeast strains were analyzed. The results showed that: in terms of fermentation cycle, the experimental group completed the rapid proliferation of microbial flora, the degradation of polysaccharides and the efficient accumulation of organic acids and total phenols on the first 35 days of fermentation. After 35 days, the indexes tended to be stable, and the fermentation period was shortened by 55 days compared with the control group of 90 days. In terms of functional components, the organic acids and total phenols in the experimental group were concentrated in the early stage of fermentation. The content of organic acids in the experimental group was 43.75 % higher than that in the control group at 45 days of fermentation (P＜0.05), and the total phenol content of the experimental group was 55.6% higher than that of the control group at 35 days of fermentation (P＜0.05). The activities of protease and β-glucanase in the experimental group reached the peak at 35 and 60 days (9078 U·L⁻¹, 3321 U·L⁻¹), respectively, which were significantly higher than those in the control group (P＜0.05). In terms of the number of effective viable count, the number of viable bacteria in the experimental group was significantly higher than that in the control group (P＜0.05). The highest viable count of yeast was 6.0 × 10¹³ CFU·mL⁻¹, and the highest viable count of lactic acid bacteria was 5.5 × 10¹⁰ CFU·mL⁻¹. In conclusion, the yeast-inoculated mixed fermentation mode performed well in shortening the process and improving the quality of Wendan pomelo ferment, which not only verified the applicability of the compound mode of "natural fermentation plus exogenous yeast" in the preparation of Wendan pomelo cracked-fruit enzyme, but also provided scientific reference and practical basis for the high-value utilization of by-products in Wendan pomelo industry.