| dc.description.abstract | The culture of drinking tea originated in China, it has history of thousands of years.
The influence of tea culture is not only in the Asia, but also in the Europe. In the early
17th century, the Netherlands and Portugal brought Chinese tea culture to the Western
world through trade, triggering a huge wave of tea drinking. Nowadays, drinks of tea
are loved by the general public, and its consumption is merely second to water. Many
studies have confirmed that tea has various health effects on the human body, such as
enhancing the body′s immunity and lowering cholesterol. Tea contains a large amount
of polyphenolic compounds, and it makes tea have excellent antioxidant activity. γaminobutyric acid (GABA)—an amino acid that widely exists in animals and plants. It
exists in the brain and nervous system in the human body. Its main function is to calm
the nerves and adjust emotions. Recently, people have used GABA to improve insomnia.
In this study, Agaricus blazei Murill TITC1 and Lactobacillus buchneri BCE119151
were used as our fermentation strains. Under the optimal medium conditions obtained
in previous research in our laboratory, the extracts of green tea (Camellia sinensis) and
oil camellia (Camellia oleifera) are used into two-stage fermentation, the purpose is to
produce fermented tea with high GABA content and also to explore the operating
conditions and details that affect GABA production. Agaricus blazei Murill are rich in
different amino acids. One of them, glutamic acid is the most important. As a precursor
of γ-aminobutyric acid, it can stimulate the glutamic acid decarboxylase, GAD in
Lactobacillus buchneri to produce a lot of GABA. Under the two-stage fermentation of
these strains, the fermented tea can be more beneficial for human body.
During the first stage of Agaricus blazei Murill fermentation, it was found that the
presence or absence of tea powder in the culture affected the GABA concentration in
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final product. During the experiment, the tea extract and tea powder were separated and
only used extract into culture. The final GABA concentration of product was higher than
the product that was from the culture containing tea powder. In the second stage of
fermentation of Lactobacillus buchneri, whether the survival of Agaricus blazei Murill
affected the concentration of final GABA products was tested. There was no significant
difference in the results of the two conditions. Tried to compare with oiltea Camellia、
green tea、black tea and oolong tea for fermentation culture, finally I get the final GABA
concentration for them with 25.94 g/L、28.62 g/L、29.18 g/L 和 29.55 g/L. Considering
the caffeine by YC/G (Caffeine per milligram / GABA per gram), oiltea Camellia will be
the best fermentation culture. | en_US |