Effects of processing technology on tea quality analyzed using high-resolution mass spectrometry-based metabolomics
1Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China; State Key Laboratory of Plant Environmental Resilience, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Food Chemistry
|January 26, 2024
Summary
Steaming green tea preserves more sweet-tasting compounds like free amino acids, while frying results in more bitter compounds such as catechins. This difference in chemical composition affects the final flavor profile of the processed green tea.
Area of Science:
- Food Science
- Agricultural Chemistry
- Plant Biochemistry
Background:
- Fixation is a critical step in green tea processing, significantly influencing the final product's quality.
- Different fixation methods, such as steaming and frying, can alter the chemical composition of green tea.
- Understanding these chemical changes is essential for optimizing green tea production and achieving desired sensory attributes.
Purpose of the Study:
- To investigate and compare the chemical component profiles of steamed green tea and fried green tea produced from the same batch of fresh tea leaves.
- To identify specific compounds that are differentially abundant between the two processing methods.
- To correlate the observed chemical differences with the distinct sensory characteristics (mellowness, bitterness) of steamed versus fried green tea.
Main Methods:
- Utilizing the same batch of fresh tea leaves for both processing methods to ensure comparability.
- Employing steaming as one fixation method and frying as the alternative fixation method.
- Analyzing and comparing the chemical compositions of the resulting steamed and fried green teas using advanced analytical techniques (e.g., chromatography, mass spectrometry).
Main Results:
- Steamed green tea exhibited significantly higher concentrations of sucrose and free amino acids compared to fried green tea.
- Fried green tea showed higher abundances of 12 compounds, including purine nucleoside and pyrimidine nucleoside derivatives, and catechins.
- Steamed green tea contained higher levels of 34 compounds, notably amino acids and their derivatives, benzofurans, and flavonoids.
Conclusions:
- Steaming fixation retains a greater number of compounds associated with sweet and fresh tastes, primarily free amino acids.
- Frying fixation leads to the production of more compounds contributing to a bitter taste, such as catechins.
- The distinct chemical profiles resulting from steaming and frying fixation explain the observed difference in flavor, with steamed green tea being mellower than fried green tea.
