Effects of starter culture and sweetener on biochemical compounds and microbial diversity of kombucha tea

Kombucha tea has been claimed to have several health benefits. Many factors influence the properties of kombucha tea produced. This study focused on the effects of starter cultures (kombucha liquid broth (KLB) and cellulosic pellicle (KCP)) and sweetener (white sugar (S), honey (H) and jaggery (J)) used in the production of kombucha tea. The results showed that all kombucha teas prepared using KLB had a lower pH and a higher concentration of acetic acid during fermentation. The ethanol content for samples prepared using KLB increased (0.7 ± 0.26 mg/L to 1.73 ± 0.58 mg/L) during the fermentation period, compared to KCP which was the maximum after 72 h fermentation, and continued to decrease (2.97 ± 1.24 mg/L to 0.90 ± 0.44 mg/L). Although not too much differences in pH and ethanol content were observed when different sweetener sources were used, they did have significant differences in antioxidant properties and antimicrobial activity. Samples prepared using jaggery had the lowest antioxidant activity while kombucha tea prepared using KLB and white sugar (KLB-S) had the highest antioxidant and antibacterial activity and was mostly colonized by Acetobacteracea and Aspergillus fumigatus. Fermentation significantly increases the number of active compounds present in KLB-S from 11 to 25 compounds. New compounds such as docosanedioic acid, muramic acid and thiolactomycin were formed. Thiolactomycin, a natural antibiotic is suggested to contribute to the high antimicrobial activity of KLB-S. In conclusion, KLB and white sugar are better suited in preparing kombucha tea as more benefits and consistent results were observed