High Levels of Major Components and Antioxidant Activity of Fermented Tea Treated with Lactococcus lactis subsp. cremoris

Abstract

Tea is a popular drink all over the world and has been attracting attention for its beneficial health effects. We developed a fermented tea by processing it with an exopolysaccharides-producing lactic acid bacterium, Lactococcus lactis subsp. cremoris, in order to manufacture high-quality tea with a physiological function. Lactococcus lactis subsp. cremoriswas added to tea leaves (Camellia sinensis) and fermented for two weeks. To examine the progress of fermentation, we determined the change in pH as well as the contents of ascorbic acid and folic acid in the extract of leaves. Decreases in ascorbic and folic acids were identified, but pH only slightly changed during fermentation, showing a slower development of fermentation with lactic acid bacteria. Furthermore, we analyzed the extract’s components, such as catechins, amino acids, including theanine as the major amino acid, and caffeine. Although there were some fluctuations in contents, no significant change was seen over a period of two weeks. Fermentation had no effect on the degradation of these components, suggesting that they may be relatively stable. To investigate a potential physiological function, antioxidant activity was measured using 1,1-Diphenyl-2-picryl-hydrazyl, (DPPH). Consequently, the results showed that the activity of the extracts was unaffected by fermentation until the seventh day, when it began to increase. Our results suggested that the fermented tea developed in this study, which maintained its key components of catechins, theanine and caffeine, exhibit a physiological function as a processed tea and a novel food material.