Nonvolatile Metabolomics Of The Tea Fermented By Mixed Microorganisms

Tea is one of the most famous non-alcoholic beverages in the world,possessing favorite tastes and health benefits.Tea can be divided into six major categories of tea according to the processing methods,and green tea is the most popular,largest production and consumption tea type in China.In recent years,unsalable of green tea begin to appear with the increase of tea plantations,which has hindered the production enthusiasm of farmers and the development of the tea industry.Tea as a product can be consumed directly,and also be made into high valueadded products,such as matcha,scented tea,and many types of tea beverages.Traditional tea beverages are usually made by the concoction of beverages with tea extracts,which were proved to be popular with consumers.A new kind of probiotic fermented tea beverage then emerged and focused the attention of researchers,as their potential market value,as well as a solution to green tea unsalable problems.Therefore,this study worked on the control of the fermentation factors,optimization of the process parameters,and analysis of dynamic changes of non-volatile components during the green tea fermentation process using mixed probiotics,aimed to make a foundation for utilization of unsalable green teas.In this study,the mixed probiotics Saccharomyces cerevisiae,Lactobacillus plantarum and Lactobacillus bulgaricus were used in the fermentation of Huang shan mao feng green tea.The effects on beverage tastes of factors including sugar addition,anaerobic fermentation time,and anaerobic temperature were evaluated by single-factor experiments.The fermentation parameters were then optimized by the orthogonal experimental design.Besides,the dynamic changes of non-volatile compounds during continuous anaerobic fermentation followed by anaerobic fermentation were analyzed using metabolomic methods.The main results obtained are as follows:The single factor experiments suggested that three factors of additional of sugar,anaerobic fermentation time and anaerobic temperature are about 6 g?3 d?39 °C,respectively.The orthogonal experiment with three factors and three levels was conducted subsequently,and showed that the order of factors affecting the taste of beverages is anaerobic fermentation temperature,anaerobic fermentation time,sugar additional.The optimal ratio of fermented tea beverage was 6 g of sugar and 39 °C of anaerobic fermentation.The time of anaerobic fermentation was 2 days.The non-volatile components analysis of samples during continuous aerobic fermentation followed by anaerobic fermentation indicated that the start of aerobic fermentation increases the richness of components in tea soup,which trends to decrease with the starting of anaerobic fermentation,but still higher than the original tea soup.Besides,catechins in tea soup did not change significantly during the whole fermentation process.And with a higher temperature,the earlier reach the end of anaerobic fermentation.Finally,many components produced during the probiotic fermentation process are needed further working for structure identification.This experiment verified the feasibility to use mixed probiotics in green tea fermentation and explored the factors affecting the taste of fermented tea beverages.The optimization of the fermentation parameters and the analysis of the non-volatile components changes also laid a foundation for further researches on fermentation green tea.