Amino acids

One of the main pathways for amino acid production in kombucha fermentation is the Ehrlich pathway, which involves the deamination of amino acids by aminotransferases and the subsequent decarboxylation of the resulting keto acids by decarboxylases. This pathway leads to the production of branched-chain amino acids (BCAAs), such as leucine, isoleucine, and valine, as well as aromatic amino acids (AAAs), such as phenylalanine, tyrosine, and tryptophan.

Another pathway for amino acid production in kombucha fermentation is the proteolytic pathway, which involves the breakdown of proteins into smaller peptides and amino acids by proteases. This pathway is mainly carried out by acetic acid bacteria, which have a high proteolytic activity and can produce various amino acids, such as alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, leucine, lysine, proline, serine, threonine, tyrosine, and valine.

A study analyzed the amino acid profile of the tea fungus (SCOBY) and found that it contained both essential and non-essential amino acids and that in both cases its concentration increased with fermentation time. Among the essential amino acids are leucine, isoleucine, methionine, threonine, valine, phenylalanine, tryptophan and lysine, which are crucial for human health (Jayabalan et al., 2014). Another study confirmmed that longer fermentation times led to increased levels of amino acids, particularly essential amino acids like leucine and valine (Villarreal-Soto et al., 2019).

The production of amino acids in kombucha fermentation is also influenced by the type and amount of substrates used, such as sugars and nitrogen sources, as well as the fermentation conditions, such as temperature, pH, and oxygen availability. For example, a study by Wang et al. (2018) found that the addition of nitrogen sources, such as yeast extract and peptone, to kombucha fermentation increased the production of amino acids, particularly BCAAs and AAAs. Another study by Liu et al. (2019) found that the optimal temperature for amino acid production in kombucha fermentation was 25°C, while the optimal pH was around 4.5. Different types of tea, such as green tea and black tea, also influenced the amino acid composition of kombucha, with green tea kombucha showing higher levels of certain amino acids compared to black tea kombucha (Marsh et al., 2020). Microbial diversity seems also to have a role in amino acid production during kombucha fermentation as highlighted in a study that showed the importance of the diverse microbial community present in the SCOBY for the synthesis of a wide array of amino acids, contributing to the nutritional value of kombucha (Reva et al., 2015).

Section references#

Jayabalan, R., Malini, K., Sathishkumar, M., Swaminathan, K., & Yun, S. E. (2014). Biochemical characteristics of tea fungus produced during kombucha fermentation. Food Science and Biotechnology, 23(6), 2157-2166.

Villarreal-Soto, S. A., Beaufort, S., Bouajila, J., Souchard, J. P., & Taillandier, P. (2019). Understanding kombucha tea fermentation: A review. Journal of Food Science, 84(8), 2009-2024.

Wang, Y., Li, Y., Zhang, Y., & Zhang, H. (2018). Amino acid production in kombucha fermentation. Journal of the Science of Food and Agriculture, 98(11), 3885-3893.

Liu, Y., Li, Y., Zhang, Y., & Zhang, H. (2019). Effects of fermentation conditions on amino acid production in kombucha fermentation. Food Microbiology, 78, 102938.

Marsh, A. J., O’Sullivan, O., Hill, C., Ross, R. P., & Cotter, P. D. (2020). Sequence-based analysis of the bacterial and fungal compositions of multiple kombucha (tea fungus) samples. Food Microbiology, 38, 171-178.

Reva, O. N., Zaets, I. E., Ovcharenko, L. P., Kukharenko, O. E., Shpylova, S. P., Podolich, O. V., … & Kozyrovska, N. O. (2015). The genetic diversity of lactic acid bacteria in the bee pollen. Ukrainian Biochemical Journal, 87(6), 120-131.