Substrates and Metabolic Pathways in Symbiotic Culture of Bacteria and Yeast (Scoby) Fermentation: A Mini Review

Abstract

Kombucha is a fermented beverage that is prepared traditionally by fermenting Symbiotic Culture of Bacteria and Yeast (SCOBY) with sugar and black/green tea, which is known as Camellia sinensis leaves. The previous study analyses the microbial composition that can be obtained in Kombucha production. Study shows that yeast species and acetic acid bacteria (AAB) species are the microorganisms that involve in the fermentation process of Kombucha. Some studies emphasize the chemical composition that was obtained from the production of Kombucha drinks such as organic acids, sugars, ethanol, and polyphenols. However, further review and elucidation regarding the substrates used and metabolic activity in Kombucha fermentation is necessary. Thus, the objective of this study is to review the metabolic pathway and substrates involve in Symbiotic Culture of Bacteria and Yeast (SCOBY) fermentation. This review also collected information related to the symbiosis of fermentation by yeast and AAB pathway in Kombucha fermentation. Several pharmaceutical effects of Kombucha were also discussed to prove the health benefits of Kombucha. To produce good quality and high yield of Kombucha that can provide various health benefits to consumers, it is crucial to understand the connection between the metabolic activity with Symbiotic Culture of Bacteria and Yeast (SCOBY) during the fermentation process of Kombucha. By conducting this review work, it could provide an insightful overview and better understanding of metabolic pathways and substrates involved in SCOBY and Kombucha fermentation.

Characterization of Aroma Active Compound Production during Kombucha Fermentation: Towards the Control of Sensory Profiles

“…The amounts of residual sucrose are in accordance with those reported from previous studies on black and green tea kombuchas [ 17 , 34 ]. Degradation kinetics of this disaccharide by the yeast taxa into glucose and fructose units through the glycolysis pathway [ 49 ] allows the assimilation of simple sugars by them [ 7 , 50 ]. As a result, since the concentration of simple sugars is inversely proportional to that of sucrose, it increases during fermentation [ 3 ].…”

“…In fact, during the hydrolysis of sucrose, yeasts convert fructose and glucose simultaneously to ethanol and CO 2 on the one hand, with a more rapid utilization of fructose as compared to glucose [ 7 , 9 ]. On the other hand, the AAB preferential carbon source is glucose, principally for SCOBY, resulting in cellulose synthesis [ 9 , 34 , 48 , 49 , 50 , 51 ].…”

“…Moving to the composition of the kombucha microbiome provided by the liquid starter and the kombucha SCOBY, the ethanol produced by the yeasts is converted via various fermentative pathways into organic acids by different bacteria [ 16 , 20 , 48 , 49 , 50 ]. Therefore, among these organic acids, the kinetics of acetic acid production are staggered in time to that of ethanol: starting from 0.63 ± 0.07 g/L at the initial stage to reach 8.42 ± 1.03 g/L at the final stage ( p < 0.001).…”

“…Essentially, through the MO activity, reagents, and substrates from the fermentation media (raw matrix, carbonaceous substrate and kombucha broth) result in the formation of metabolic and aromatic products. As described previously, most known and studied metabolic pathways driving the fermentation process are glycolysis pathway allowing yeasts to degrade carbonaceous substrates into ethanol, products then implied for the synthesis of organic acids and cellulose considering AAB pathways [ 49 ].…”