Glucuronic Acid Rich Kombucha-fermented Pomegranate Juice

Abstract

This study is the first report using tea fungus “kombucha” to ferment natural pomegranate juice to produce a fermented beverage with high content of glucuronic acid, as a human health beneficial component. We profited the acetic acid bacteria and yeasts symbiotic layer, which is well known in producing pharmaceutical beverages with considerable released organic acids such as glucuronic acid. Also, we used the natural pomegranate juice with high amount of carbohydrate and acid, as a favourable substrate for the fermentation process. The yield of glucuronic acid production was monitored by cultivating natural pomegranate juices under the 17 optimized-combinations of three distinct sucrose concentrations, fermentation temperatures, and processing time. The combinations were designated by applying the statistical response surface methodology method. The maximum amount of glucuronic acid 17.074g/l determined in the media with 8g/l supplementary sucrose after 14 days fermentation at 37°C, using high-performance liquid chromatography. Along with glucuronic acid production, effect of the three factors - sugar concentration, processing temperature and time - was also examined on changes of five physical and chemical properties of the fermented pomegranate juices, including; pH value, remained sucrose and reducing sugar content, kombucha layer biomass, and total acidity. Within 14-day fermentation process, the pH values showed decrease, the layers’ mass presented considerable increase, and the total acid content increased in the beverages. Overall, obtained data suggested that natural pomegranate juice can be a potential candidate for further development as a functional beverage to support the maximum human daily intake of glucuronic acid (45mg for a 70kg adult).