Kombucha fermentation of six medicinal herbs: Chemical profile and biological activity

Abstract

Bioactive properties, as well as chemical composition and sensory characteristics of traditional and alternative kombucha broths were examined. Samples were produced by adding 10% of kombucha starter to sweetened (7% sucrose) decocts of black and green teas (traditional substrates) and infusions of winter savory (Satureja montana), peppermint (Mentha?piperita), stinging nettle (Urtica dioica), wild thyme (Thymus serpyllum), elderberry (Sambucus nigra) and quince (Cydonia oblonga), at 25?C. Fermentation lasted the shortest with elderberry (3 days) and the longest with quince (10 days). The samples with black tea and peppermint had the best sensory quality. In general, alternative products had better antioxidant activity to hydroxyl radicals than the traditional ones, reducing power and angiotensin-converting enzyme inhibitory activity. The most pronounced acetic acid content was obtained with elderberry substrate. Moreover, peppermint substrate showed the highest values both for total phenols and total flavonoids contents. Taken together, the samples produced with the alternative substrates highlighted a higher phenolic and flavonoid contents, compared to the ones obtained with the traditional substrates.