Changes of physicochemical properties, bioactive compound, antioxidant and antimicrobial activity in tamarillo fruit juice (Solanum betaceum Cav.) during fermentation by Lactobacillus plantarum

This study aimed to examine changes in physical and chemical properties, bioactive components, and antimicrobial and antioxidant activities in tamarillo fruit juice fermented by Lactobacillus plantarum. Tamarillo fruit juice was fermented for 96 hours. The total microbial, titrated acid and pH were tested during fermentation every 6 hours. Changes in color, viscosity, total phenolic, total flavonoid, anthocyanin, and antioxidant activity were tested at 0, 24, 72, and 96 hours. The results showed that L. plantarum could grow well on tamarillo fruit juice, which was characterized by an increase in the number of cells from 2.6×107 CFU/mL (0 hours) to 7.3×108 CFU/mL (24 hours) and 3.8×1012 CFU/mL (96th hour). Fermentation of tamarillo fruit juice by L. plantarum caused a decrease in pH from 3.62 to 3.31 and increased total titrated acid from 1.58% to 2.49%. The antioxidant activity continued to decrease during fermentation. In contrast, the antimicrobial activity increased against Bacillus subtilis and Staphylococcus aureus. It can be concluded that the fermentation process causes changes in the physical, chemical, and bioactive components of tamarillo fruit extract and has an impact on reducing antioxidant activity but increasing antimicrobial activity.