Biochemical And Microbial Changes During Fermentation Of Tea Fungus (KOMBUCHA)
Selma El Siddig Ahmed, Hamid Ahmed Dirar
This research was carried out to study the biochemical and microbial changes that occur during the fermentation of tea fungus. Tea fungus, also known as Kombucha, is a fermented beverage resulting from the heavy gelatinous growth of a consortium of microorganisms in tea extract and is a popular drink in many parts of the world. The study revealed that yeast is dominant over the bacteria at the beginning of fermentation; this microbial balance is changed during fermentation and later adjusted to what it was at the beginning. Microbial investigation indicated that during the fermentation process bacteria dominate and that Acetobacter xylinum is the primary organism in Kombucha, associated with some yeast species of the genera Pichia, Candida, and Debaryomyces Proximate analysis revealed that Kombucha is composed of 57.59% fiber and30.21% other carbohydrates, in addition to proteins, fats, and ash, that together make 12.20% of Kombucha dry weight. The study shows that the PH of tea extract dropped from 6.5 to 3.5 immediately after inoculation and remained around it during fermentation, while both total titratable acids and total volatile acids increased. Increasing sugar or tea concentration in the sugared tea extract is always associated with an increase in Kombucha dry weight. Kombucha responded variously when it was incubated at different temperatures, which affected the rate of production of total titratable acids (as lactic acid) and total volatile acids (as acetic acid). Kombucha formation was affected negatively when it was shaken at a velocity of 150 rpm; only a few suspended Kombucha-like granules were formed. Both Kombucha and unfermented tea extract exhibited antibacterial activity against Klebsiella sp., Salmonella typhi, Staphylococcus aureus, and Pseudomonas sp. This ability seems to be more efficient in Kombucha than in unfermented.
Keywords: acetic acid, acetobacter, lactic acid, ph, protein, temperature
Citation: Doctoral dissertation, B.Sc. (Agric) University of Khartoum
Study Mailing Address:
Department of Botany and Agricultural Biotechnology,Faculty of Agriculture,University of Khartoum
Date Updated: March 26, 2020