This study investigated the biotransformation of red goji berry ( Lycium barbarum ) via kombucha fermentation and its impact on the composition of bioactive metabolites, functional activities, and sensory evaluation. Kombucha was prepared with 1, 3, and 5% (w/v) goji berries and fermented for 14 days. Fermentation significantly decreased pH and sugar levels while increasing titratable acidity, indicating active production of organic acids. Total phenolic, flavonoid, tannin, and vitamin C contents increased during fermentation, thereby enhancing antioxidant capacity. The highest DPPH radical scavenging activity was observed in 5% goji berry kombucha (121.79 mg/L vitamin C equivalent). LC–MS profiling revealed enrichment of fermentation- and fruit-derived metabolites, including acetic acid and glucuronic acid as predominant organic acids, together with hydroxycinnamic acid derivatives, ferulic acid, rutin, and phenylamide compounds originating from goji berry. The fermented beverage showed strong antibacterial effects against Escherichia coli and Staphylococcus aureus , likely due to the combined action of organic acids and phenolic compounds. It also exhibited better α-glucosidase inhibitory activity than the non-fermented extract, suggesting greater antidiabetic potential. Safety tests using Zophobas morio larvae and HaCaT keratinocytes confirmed that the beverage is non-toxic and cell-compatible. Sensory evaluation with trained panelists using a nine-point hedonic scale found that the beverage was well accepted overall, with the 3% (w/v) goji berry kombucha receiving the highest scores. These results show that kombucha fermentation enhances the functional and health-related properties of goji berries while maintaining the beverage's safety and consumer appeal, supporting its use as a functional fermented drink.
Candra et al. (Fri,) studied this question.