Kombucha is a fermented beverage prepared from infusing tea leaves with a symbiotic association of bacteria and yeasts. While white sugar is the commonly known as energy source for this beverage, the usage of other sweeteners has not been studied. In this investigation, the following sweeteners were used for preparation of the Kombucha: Artificial sweetener -Aspartame, bees' honey, brown sugar, white sugar, glucose, kitul palm honey (Caryota urens), palmyrah jaggery (Borassus flabellifer) and sucrose. The phenolic compounds and antioxidant and starch hydrolase inhibitory activities were studied. Brown sugar, white sugar, glucose and sucrose were the most effective in producing high antioxidant and starch hydrolase inhibitory activities. However, usage of bees' honey, Caryota urens honey and palmyrah jaggery had not deterred the fermentation. Thus, although noteworthy changes to the antioxidant and starch hydrolase inhibitory activities were not observed, they could be used as alternative low-cost sweeteners for the preparation of Kombucha. PRACTICAL APPLICATIONSKombucha is an herbal beverage with a multitude of therapeutic properties. It is traditionally prepared by fermenting sugared black tea with a consortium of bacteria and yeast. Whether the addition of sugar could be replaced with other types of sweeteners especially those which are abundantly available and in use as indigenous ingredients is an aspect worthy of pursuing. This study explored this aspect using bees' honey, the jaggery of Borassus flabellifer and the honey from Caryota urens as well as an artificial sweetener -Aspartame. Although the fermentation process has been effectively carried out by the microbes, the functional properties such as antioxidant and starch hydrolase inhibitory activities of the beverages were effected through substitution of sugar with these alternative sweetening agents. Thus, the study highlights that although indigenous sweetening agents may prove to be tempting as alternative sweeteners for the preparation of Kombucha, the therapeutic effects would be compromised.

The objective of this study was to evaluate and compare antioxidant and starch hydrolase inhibitory activity of three different types of Kombucha beverages prepared by three pellicles with different microbial compositions. The fermentation process was carried out for 7 days and the assessments of antioxidant and starch hydrolase inhibitory activities as well as tea phenolic compounds were carried out. These parameters were also evaluated after subjecting the final fermented samples to gastric and duodenal digestion in anin vitrodigestion model. The pH had a statistically significant decrease during the period of fermentation. The total phenolics content and antioxidant activities had increased during the fermentation process as well as when subjected to digestion. The starch hydrolase inhibitory activities also increased in a similar manner during the different phases. Theα-amylase andα-glucosidase inhibitory activities showed statistically significant increases(P<0.05)as the fermentation progressed, while an increase was observed after being subjected to pancreatic and duodenal digestion as well. All three types of tea showed a higherα-amylase inhibitory activity thanα-glucosidase inhibitory activity.

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