Effects of different fungal strains on nutritional characteristics, antioxidant activity, and volatile compounds in fermented sugarcane juice

In this study, the effects of microbial fermentation on the nutrient composition, antioxidant activity, and volatile compounds of sugarcane juice were investigated using different strains of Monascus purpureus ( M. purpureus ) and Aspergillus niger ( A. niger ) , both individually and as a co-culture. The results indicated a significant decline in the soluble sugar content of sugarcane juice after fermentation, with 50% reduction observed after 48 h (p<0.05), suggesting that these strains utilized the soluble sugar for fermentation. The pH increased from 5.3 to 6.4 after 144 h of fermentation in the M. purpureus group, while decreasing from 5.3 to 4.4 in the A. niger and co-culture groups. The fermentation broth contained 17 types of free amino acids. The content of free amino acids decreased notably from 0 to 96 h (p<0.05), and then it exhibited slight changs a little from 98 to144 h in the M. purpureus and co-culture groups. In contrast, free amino acids were almost completely depleted in the A. niger group. Phenol concentrations increased significantly in the A. niger and co-culture groups (p<0.05). Notably, fermentation broths demonstrated excellent antioxidant activity. The types and concentration of flavor components in the sugarcane juice were enhanced by microbial fermentation, which improved its flavor and flavor profile. Alcohol levels, particularly the content of isobutanol and isoamylol increased significantly in the co-culture group (p<0.05). These results showed that an M. purpureus and A. niger co-culture is suitable for sugarcane juice fermentation with a process time of 48–96 h.