The team of Professor Gao Hong from the School of Light Industry Science and Engineering of Sichuan University has made important progress in the utilization of summer and autumn tea resources and the research of dark tea

Editor in charge: Food Science

Recently, the team of Professor Gao Hong from the School of Light Industry Science and Engineering of Sichuan University used autumn tea as a raw material to ferment the autumn tea with the patented strain "Santocystis cristatum PW-1" to explore the effects of the strain PW-1 The improvement effect and mechanism of tea quality, related research results were published in the top journal Food Chemistry in the field of food science and technology with the institute as the first unit , entitled "The effect of Eurotium cristatum (MF800948) fermentation on the quality of autumn green tea"
.
The doctoral student Xiao Yue of the school is the first author, and Professor Gao Hong is the corresponding author.
The project was supported by the Sichuan Science and Technology Project Fund (No.
20ZDYF3186)
.

The tea industry is a traditional advantageous industry in China.
Its planting area and output rank first in the world, and it has become an efficient industry for rural revitalization in China
.
According to the different seasons of tea picking, green tea can be divided into spring tea, summer tea and autumn tea
.
Due to the high temperature in summer and autumn, the carbon metabolism level of tea plants increases, and the nitrogen metabolism level decreases, resulting in higher polyphenols in summer and autumn tea than spring tea, while the content of amino acids and aromatic substances is low, resulting in a bitter taste and aroma in summer and autumn tea.
Poor, the quality is far inferior to spring tea
.
However, about 60% of China's green tea production is summer and autumn tea.
Because of its low economic benefits and high picking costs, a large number of summer and autumn tea leaves have not been picked, resulting in a huge waste of resources
.
Therefore, reducing the astringency of summer and autumn tea, improving the aroma quality of summer and autumn tea, and developing the use of summer and autumn tea have become an urgent problem to be solved
.
The team of Professor Gao Hong of our hospital uses autumn tea as the raw material and uses the method of microbial fermentation to produce a new type of black tea with good taste and aroma quality, which is of great significance for guiding the development of tea correctly, meeting consumer requirements and improving economic benefits
.

Catechin, especially epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) are the most important source of the bitter taste of tea
.
After the autumn tea was fermented by Pw-1, the total amount of catechins dropped from 118.
35 mg/g to 10.
58 mg/g, a decrease of 91.
06%; and the esterified catechins EGCG and ECG in the fermented autumn tea The contents of PW-1 were 0.
37 mg/g and 0.
40 mg/g, respectively, indicating that fermentation of strain PW-1 can significantly reduce the catechin content in autumn tea
.
Using electronic tongue technology to analyze the taste characteristics of autumn tea and PW-1 fermented autumn tea, it was found that the astringency of autumn tea was significantly reduced and the umami intensity increased, indicating that autumn tea was fermented by strain PW-1 The taste quality afterwards has been significantly improved
.
In addition, through the electronic tongue technology to analyze the taste characteristics of theafuscin for the first time, it was found that theafuscin has no astringency but a strong umami taste, and it is the main flavoring substance in the fermented autumn tea
.

The results of GC-MS analysis showed that the content of alcohol volatile components in autumn tea was significantly increased after the fermentation of Sansophora cristatum PW-1.

Among them, the ( Z )-linalool oxide and linalool which have a floral and fruity fragrance , ( E )-linalool oxide (furan type) and 1-octen-3-ol had the highest content, indicating that strain PW-1 significantly improved the aroma quality of autumn tea

This work integrates the knowledge and professional technology of food science, microbiology and metabolomics.
From the perspective of the high-value sustainable utilization of summer and autumn tea, focusing on the taste and aroma quality of tea, the microbial fermentation technology tries to improve the quality of summer and autumn tea and solve the problem of summer and autumn tea.
Tea resource waste and other issues, in order to promote the high-value sustainable use of autumn tea, not only can effectively increase the income of tea farmers, but also promote the healthy development of the tea industry
.

Corresponding author introduction

Professor Gao Hong

Gao Hong, born in April 1973, doctor (post), professor, doctoral supervisor, director of the Food Biochemistry Laboratory of Sichuan University, and deputy dean of the Agricultural Products Processing Research Institute

.
Ph.
D.
[Post] from Hokkaido University, Japan, Researcher of the Japanese Society for the Promotion of Science (JSPS), the eighth batch of Sichuan academic and technical leaders reserve candidates, 2010 new century outstanding talent support program candidates, 2012 Sichuan outstanding young academic and technical leaders ; Now concurrently serving as reviewer for China Scholarship Council, Doctoral Program Fund of the Ministry of Education, China Scholarship Fund, Science and Technology Progress Award of Higher Education Ministry of Education, Sichuan Province Food Safety Standards; Reviewer of journals such as Food Chemistry , Journal of Agricultural and Food Chemistry , Food Editor of Science and Human Wellness
.
Research field and content(1) Research and development of functional foods; (2) Research and development of anti-metabolic syndrome (MS) medicinal foods; (3) Development and utilization of new food materials; (4) Bioactive substances in foods (Mainly refers to natural products such as phenols and alkaloids) research on digestion, absorption and metabolism; (5) Research on the effects and mechanisms of plant polyphenols and polysaccharides on intestinal flora and intestinal immunity; (6) Food Safety evaluation (long-term repeated toxicity test, reproductive toxicity, genetic toxicity, etc.
, and analysis of residual pesticides and organic compounds in food that are harmful to humans); (7) Development and utilization of functional cosmetics derived from natural materials; (8) Exploration and utilization of active substances in natural products with medicinal value; (9) Exploration and utilization of new antibacterial agents in natural products; (10) High-frequency utilization of microbial metabolites
.