Kombucha Fermentation of Olympus Mountain Tea (Sideritis scardica) Sweetened with Thyme Honey: Physicochemical Analysis and Evaluation of Functional Properties

Abstract

This study implemented kombucha fermentation of Olympus Mountain tea (Sideritis scardica) sweetened with honey (OMTWH) in order to investigate the potential for producing a novel beverage with functional properties. The increase in the total count of bacteria and yeast suggests that the OMTWH acts as a viable substrate for supporting the proliferation of the microorganisms of the Kombucha symbiotic culture. The fermentation resulted in a reduction in pH and increased total titratable acidity. After fermentation, a statistically significant increase in the vitamins C, B1, B2, B6, B7, and B12 content was observed (p < 0.05). Total phenolics and antioxidant activity of the fermented beverage was significantly enhanced, as assessed by the method of Folin–Ciocalteu and ABTS assay, respectively. Results revealed that OMTWH had a potent inhibitory activity of α-amylase, α-glucosidase, acetylcholinesterase, and butyrylcholinesterase; OMTWH fermented with a kombucha consortium exhibited even higher inhibition. Hence, the process of kombucha fermentation can convert OMTWH into a novel beverage with enhanced functional properties.

Evaluating the Effect of Adding Selected Herbs, Spices, and Fruits to Fermented Olympus Mountain Tea (Sideritis scardica) Kombucha Sweetened with Thyme Honey: Assessment of Physicochemical and Functional Properties

“…That indicates an increase in the inhibition of α-amylase with the rise in the total phenolic content and the ABTS antioxidant capacity of the samples. The above agrees with previous studies [30,37,79].…”

“…This association was quantified using Spearman's connection coefficient, which was calculated at −0.574 (p < 0.01). In line with our previous study [30], we found a significant negative correlation between the total phenolic content and ABTS IC 50 values (Pearson's correlation coefficient = −0.837, p < 0.01). Additionally, we observed a moderate negative correlation between the total flavonoids and ABTS IC 50 values (Pearson's correlation coefficient = −0.370, p ≤ 0.05) during the fermentation of Olympus Mountain tea sweetened with honey in the kombucha process.…”

“…This association was quantified using Spearman's connection coefficient, which was calculated at −0.574 (p < 0.01). In line with our previous study[30], we found a significant negative correlation between the total phenolic content and ABTS IC 50 values (Pearson's correlation coefficient = −0.837, p < 0.01). Additionally, we observed a moderate negative correlation between the total flavonoids and ABTS IC 50 values (Pearson's correlation coefficient = −0.370, p ≤ 0.05) during the fermentation of Olympus Mountain tea sweetened with honey in the kombucha process.On the other hand, DPPH IC 50 values had a strong negative correlation with total flavonoids (Spearman's correlation coefficient = −0.811, p < 0.01) and a medium correlation with total phenolic content (Spearman's correlation coefficient = −0.683, p < 0.01).Several studies have shown that extracts of hibiscus calyces have a potent antioxidant effect[66][67][68][69].…”

“…The statistically insignificant change in the flavonoid content after the enrichment with ginger, turmeric, lemon zest, and juice could be explained by the small quantities added, the fact that ginger and lemon are in a fresh state, the considerably low flavonoid content of the above, and the acidic environment of K. Previous research indicated that the acidic nature of the fermented kombucha beverage led to the breakdown of flavonoids [64]. Also, a decreased flavonoid content of Olympus Mountain tea sweetened with honey after kombucha fermentation has been previously reported [30].…”

“…After the preparation of a fermented Olympus Mountain tea kombucha with honey (K) in three replications (A, B, C) as previously described [30], herbs, spices, and fruit were added (Figure 1). The aim was not to overpower the aroma of kombucha with Mountain tea and honey completely, so the maximum quantity of herbs, spices, and fruits for enrichment was set at 0.5% w/w (equal to the amount of Mountain tea added).…”