Influence of fruit maturity and lactic fermentation on physicochemical properties, phenolics, volatiles, and sensory of mulberry juice

Mulberry fruits harvested at commercial ripeness were sorted into five maturity groups (S1–S5) according to their density, and their juices were separately fermented at 37 °C for 36 h using Lactobacillus plantarum strain Lp-01. The physicochemical properties, phenolic profile, antioxidant activity, flavor profile, and sensory characteristics of mulberry juice (MJ) were then determined. The findings revealed that MJs were suitable matrices for LP-01 growth, particularly for MJ-S5 with a high content of phenolics, glucose, and fructose, with more than 12 log CFU/mL of viable counts and 19.64 mg/mL of lactic acid at the end of fermentation. Lactic acid bacteria (LAB) fermentation dramatically increased total phenolics, total flavonoids, and antioxidant capacities, while promoting anthocyanin transformation of MJs. Moreover, cyanidin-3-O-glucoside (C3G) was significantly decreased by LAB fermentation and negatively correlated with caffeic and chlorogenic acid contents (p＜0.05). Lp-01 fermentation enhanced the total aroma content and complexity of flavor, specifically in MJ-S5 which resulted in the total aroma content increased by 54.96 mg/L and 11 new flavor volatiles formation. Furthermore, MJ-S3 fermentation product was the most attractive for consumers. These results will be valuable in controlling of mulberries product quality precisely.