Abstract

Fermented beverages obtained from plant-based raw materials are becoming more popular due to their beneficial effects on human health. These include kombucha beverages, which are obtained by fermenting tea brew using the so-called tea fungus, which includes acetic acid bacteria and osmophilic yeast. A consortium of these microorganisms could also be used to prepare functional fermented beverages obtained from extracts of vegetable pomace. These valuable by- products of vegetable processing are a precious source of e.g., antioxidants, dietary fiber and mineral salts. Extraction of ingredients from pomace, combined with subsequent fermentation using tea fungus, could produce products with interesting sensory characteristics and significant health-promoting potential. The purpose of this study was to evaluate the physicochemical and health-promoting properties of fermented beverages obtained from extracts of beetroot and carrot pomace, using tea fungus as a starter culture. During the fermentation process, the following changes were determined: pH, titratable acidity (TA) and saccharide content. The health- promoting properties of the obtained beverages were identified by determining antioxidant and antimicrobial activity against pathogenic microorganisms: Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, Salmonella Paratyphi, Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Pseudomonas aeruginosa. During fermentation of extracts from carrot and beetroot pomace extracts, a decrease in pH and an increase in TA were observed. The greatest changes in pH occurred during the first 5 days of fermentation. After this time, the pH value does not change, remaining constant at around 3.0 in all beverages. TA, on the other hand, increases through the entire fermentation process. Sucrose added to beverages was observed to be completely metabolized by microorganisms to glucose and fructose. On the last day of fermentation, only glucose was detected. The antioxidant activity of fermented beverages increases with the duration of fermentation. The obtained beverages also show antimicrobial activity against the tested microorganisms.

Authors (2)