This study aimed to prepare kombucha, a fermented tea beverage, containing Dendropanax morbiferus (DM) leaves and roots, and analyze its antioxidant and intracellular activities. We compared the pH change, total acidity, radical scavenging activity, and oxygen radical absorbance capacity (ORAC) of kombucha fermented with black tea alone and that with added DM leaves or roots during fermentation. Using RAW 264.7, we evaluated the effects of kombucha containing different DM parts on nitric oxide (NO) production and inflammation-related cytokine content in cells. Kombucha containing ethanol extracts of DM leaves (BTK-E-DML) and roots (BTK-E-DMR) showed higher radical scavenging activity and ORAC 3 d after fermentation than that prepared from black tea alone (BTK-Ori). In an in vitro experiment using RAW 264.7, samples were treated with 8 mg/mL kombucha considering cytotoxicity; the lipopolysaccharide (LPS)-induced NO content significantly reduced after BTK-E-DML and BTK-EDMR treatments compared with that after BTK-Ori treatment. Additionally, the levels of interleukin-6 and tumor necrosis factor-alpha, which were LPS-stimulated inflammatory cytokines, significantly decreased in cells treated with BTK-E-DML and BTK-E-DMR 15 d after fermentation compared with those treated with BTK-Ori. In conclusion, these results demonstrate that kombucha fermented with the leaves and roots of DM increases antioxidant activity and can significantly regulate inflammatory responses at the cellular level.

In this study, kombucha was prepared by adding 0%, 25%, 50%, 75%, and 100% of Orostachys japonicus as a natural functional source to broaden its usage and obtain valuable data for fermented beverage research. The kombucha’s pH and sugar content decreased during the fermentation period, but its acidity level increased during the same period. Additionally, its L value increased after decreasing, its a value decreased after increasing, its b value continued to increase, and its sugar reduction increased and then decreased. In the sensory characteristic strength evaluation, its color, fermented odor, and sour taste became stronger, but its sweetness became less. As a result of preference evaluation, fragrance and swallowing capability stood the highest in the 25% addition group, color and taste were the highest in the 50% addition group, and overall preference was highest in the 50% addition group. Total flavonoids, total polyphenols, DPPH, ABTS radical scavenging ability, and reducing power increased until the third day of the experiment and decreased afterward. Therefore, the study determined that fermenting kombucha with 50% Orostachys japonicus extract for 9 days would increase its quality characteristics and provide the most palatability.

본 연구에서는 복분자 콤부차의 최적 배합비를 찾고 이화학적 특성과 항산화 활성을 알아보았다. 반응표면분석법을 통해 복분자 콤부차의 최적 배합비는 홍차 농도 10% (w/v), 복분자 농도 8.09% (w/v)로 나타났고 이 배합비로 홍차 발효 주정에 복분자 당침액과 균을 첨가하여 14일간 초산 발효와 젖산 발효 과정을 통해서 산도 4%와 pH 2.77인 콤부차를 만들 수 있었다. 복분자 콤부차의 주요 유기산은 acetic acid, lactic acid, oxalic acid로 나타났으 며 그 중에서 acetic acid가 3,705.34 mg/100 mL로 가장 높았다. 발효 후 총 폴리페놀의 함량은 763.33 μg CE/mL 로 발효 전보다 증가하였으나 콤부차 발효 후 DPPH, ABTS 라디칼 소거활성을 측정한 결과 항산화활성은 각각 46.09%, 89.81%로 발효 전보다 감소하는 것을 확인할 수 있었다. 또한 반응표면분석법을 통해 얻은 최적 배합비의 종속변수 예측값과 최적 배합비 콤부차 실험값의 산도의 평균차는 0.065, 유기산의 평균차는 0.041, ABTS 라디칼 소거활성의 평균차는 0.061이므로 예측값과 실험값은 유사 하다.

Kombucha is a fermented tea manufactured by adding various microorganisms and sugars to brewed herb tea such as green tea and black tea. Its components and functions vary depending on ingredients, inoculated microorganism compositions, and fermentation conditions. Therefore, this study aims to examine which conditions affect kombucha properties and how these features are affected. Types of substrates, specifically plant-based foods, alter profiles of polyphenol, organic acids, carbohydrates, and protein amounts in kombucha. Long fermentation time raises polyphenol contents and high fermentation temperatures increase sourness in kombucha. Microbial composition of SCOBY, which is the symbiotic culture of bacteria and yeast used to inoculate microorganisms, change the kombucha microbiome that contributes to the chemical composition and functions of kombucha. Several studies have discovered that kombucha has health beneficial functions such as antioxidant activity, hepatic protective effects, antimicrobial effects, anti-diabetic effects, anti-inflammatory effects, and cholesterol reducing effects. These findings indicate that kombucha has high potential as a health functional food. However, future studies are needed to further determine the relationship of manufacturing conditions and functional properties of kombucha.