Determination of Optimal Kombucha Fermentation Duration and the Effect of Substrate to the Antibacterial and Antioxidant Activities of Kombucha

Wong, Le Wei (2021) Determination of Optimal Kombucha Fermentation Duration and the Effect of Substrate to the Antibacterial and Antioxidant Activities of Kombucha. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Kombucha is a carbonated beverage made from fermenting sweetened green or black tea (Camellia sinensis) with a culture containing a symbiotic consortium of bacteria and yeasts (SCOBY or tea fungus). It is known for its probiotic nature and healthy nutritional values. However, there is a lack of research work about the optimum fermentation period of kombucha, as well as a holistic view about the impacts of the substrate on the final outcomes of the fermentation process. This study aimed to determine the optimal duration of kombucha fermentation by investigating the effects of types and concentration of plant-based substrates on the antibacterial and antioxidant activities of kombucha. Primary scientific research articles were searched and extracted from the databases including ScienceDirect, Scopus and Semantic Scholar. Research studies have been selected according to the decided eligibility criteria, whereas the findings were shown through figures and textual explanations. The results demonstrated that the antibacterial and various antioxidant activities increased over time in the most studied kombucha. However, the acidity of the kombucha also increase over time where it can reach higher than optimal consuming acidity of 3.5-4.5 g acetic acid/L acids after the fermentation time ranged from day 4 to 12. The study also found that the antibacterial and antioxidant activities are greatly dependent on the concentration and types of the substrate used for kombucha fermentation. Sufficient nitrogen sources from substrates are critical for microbial metabolism, which then increased the production of organic acids and thus the antibacterial activity as a whole. The initial phenolic content in the tea substrates affects total phenolic and flavonoid content where higher concentration of substrate will result in higher total phenolic and flavonoid content in the kombucha after subjected to microbial degradation or biotransformation, consequently increased the antioxidant potentials of kombucha. Besides, substrates which were more favorable for microbial growth and possessed phenolic compounds with higher antioxidant potentials found to be more beneficial for kombucha fermentation.