Title : Studies on biofilm growth and total polyphenolic content of fermented beverages
Abstract:
Fruit vinegar and kombucha are two types of fermented drinks known worldwide. They are produced by the selected types of microorganisms from fruits or infusions. Thus, these beverages are recognized as beneficial for our health due to the microorganisms and polyphenols they contain. A sweetening agent is typically used in both beverages, e.g., sucrose, brown sugar or honey. A characteristic phenomenon occurs during the production of both beverages - the formation of living biofilms. In vinegar, this biofilm is known as the "mother of vinegar," while in kombucha, it is called SCOBY (Symbiotic Culture of Bacteria and Yeast). These structures comprise plant-derived cellulose and living microorganisms (yeasts and bacteria), indicating a progressing fermentation process [1].
The reported studies analysed the influence of several factors on biofilm production and changes in the polyphenolic content of beverages and biofilm itself. Two types of vinegar (apple and raspberry) and two types of kombucha (black and green tea) were produced using sucrose or honey as a sweetening agent. A standard Folin-Ciocalteu method was used to analyse the polyphenolic content of samples [2].
It was observed that the biofilm growth is independent of the type of used fruits (in the case of vinegar) and tea (in the case of kombucha). The sweetening agent type influences the mother's or SCOBY's growth, respectively. For the total polyphenolic content, opposite conclusions were drawn based on the obtained results. A higher content of polyphenols characterizes vinegar produced with honey. Conversely, adding sucrose increases the polyphenolic concentration in analysed kombucha samples.
