Antidesma bunius (L.) Spreng., Mao berry or locally known in the Philippines as ‘bignay’, is an underutilized fruit rich in bioactive phytochemicals such as compounds with high antioxidant activity. This study investigated the enhancement of the biological and physicochemical properties of bignay through a two-stage fermentation process for beverage development. The fermented bignay with the maximum amount of phenolic compounds after the optimized fermentation process was characterized. The physicochemical properties such as the pH, total soluble solids, color, % alcohol, and % acetic acid of the phenolic-rich beverage were measured during and after the fermentation process. The biological activities namely the α-amylase and α-glucosidase inhibition, and antioxidant properties were analyzed. Phenolic profiling was also done to confirm the quantity of specific phenolic compounds in the bignay beverage after fermentation. Results showed that after the two-stage fermentation process, the phenolic-rich fermented bignay has a pH of 3.8, TSS of 7OBrix, and 0.9% acetic acid. The fermented bignay beverage had higher antioxidant and enzyme-inhibiting properties compared to the unfermented counterpart. Phenolic profiling revealed that after fermentation, there is an increase in several phenolic compounds, with gallic acid, catechin, epicatechin, ellagic acid caffeic acid, and trans-ferulic acid having the most significant increase. The findings show that the two-stage fermentation process resulted in a phenolic-rich bignay fruit beverage with high biological activities and health-promoting properties.
