Quality characteristics of kombucha made with different mixing ratios of green tea extract and yuzu juice during fermentation

Abstract

In this study, the quality characteristics of kombucha according to the mixing ratio of green tea extract and yuzu juice during fermentation were compared. The pH of the kombucha decreased as the amount of yuzu juice increased. The titratable acidity increased in a juice-concentration dependent manner during fermentation. The reducing sugar content was 1.68% in kombucha made with a mixture of 70% green tea extract and 30% yuzu juice on the 20 th day of fermentation, showing the lowest reducing sugar content. The alcohol content did not change until the 10 th day of fermentation and increased slightly thereafter. The number of lactic acid bacteria and the quantity of yeast were the highest in the samples of kombucha made with a mixture of 70% green tea extract and 30% yuzu juice. The total polyphenol content was 40.79 mg TAE/mL in the kombucha made with this combination and this also showed the highest total flavonoid content of 37.15 mg QE/mL. In addition, the sensory evaluation results showed the highest preference in all the measured parameters for kombucha made with a mixture of 70% green tea extract and 30% yuzu juice. Key words：kombucha, yuzu, green tea, mixed fermentation, quality characteristics

Antioxidant Properties of Kombucha Made with Tartary Buckwheat Tea and Burdock Tea

“…Traditionally, the substrate used for kombucha is green or black tea ( Jayabalan et al, 2007 ; Değirmencioğlu et al, 2021 ; Woo et al, 2021 ); however, due to the increased interest in kombucha and its potential health benefits, the range of ingredients and fermentation methods has now expanded to include a variety of food materials, such as apple, spinach, yuzu, and coffee bean ( Aspiyanto et al, 2017 ; Zubaidah et al, 2018 ; Bueno et al, 2021 ; Woo et al, 2021 ). Among plant sources, Tartary buckwheat and burdock are known for their high concentrations of rutin, a type of flavonoid that is broken down into quercetin in the gut ( Sun and Ho, 2005 ).…”