What is tea fermentation?

Published: Thursday 01 February, 2018

Speaking of tea, we often call that all fermented, semi-fermented, light fermented. Are these the same fermentation with our common fermented foods yogurt, wine, vinegar, etc...? What is the difference between them? Let us show you the tea fermentation.


What is fermentation

Commonly referred to as fermentation, mostly organisms for some decomposition of organic matter. The phenomenon of fermentation has long been recognized by people, but understanding its essence is a matter of nearly 200 years. Microbiology Physically defined fermentation: the process by which organisms oxidize and degrade into oxidized products and release energy is called biooxidation.

Fermentation as Defined in Industrial Production - Industrial Fermentation: Industrial production generally refers to all industrial processes that rely on the life activity of microorganisms is called fermentation, such as beer brewing and MSG production. Fermentation in food: Fermented food is a type of food made by people using beneficial microorganisms and has unique flavor such as yogurt, cheese, fermented rice, pickles, soy sauce, vinegar, bean curd, rice wine, beer, wine and so on.


Fermentation of tea - biological oxidation

People often say that Chinese tea is divided into six major types of tea according to the degree of fermentation and the integrated system. However, the term fermentative here is quite different from the above-mentioned microbial fermentation in the usual context of Chinese tea. In tea leaves, the same piece of green leaves is processed into green tea, black tea, oolong tea and the like by controlling the biological oxidation, a process also mistakenly referred to as fermentation. This process is more like a series of enzymatic reactions, perhaps more so called biological oxidation. Biooxidation of tea leaves is a series of oxidative processes by which oxidase enzymes present in the cell wall promote catechins following breakdown of the cell wall.

In the cells of tea, catechins are present in the cytosol, whereas the oxidase is mainly present in the cell wall, not mainly in the microorganism, so it is necessary to break the cell wall. This also naturally explains why fermented tea needs to be twisted. According to the different degree of oxidation of polyphenols, also distinguish the whole fermentation, semi-fermentation, light fermentation. In black tea, polyphenols is highly oxidated, then called the whole fermentation; polyphenols in oolong tea oxidation degree is about half, then known as semi-fermented.

For example, in black tea processing, the purpose of fermentation is to oxidize the catechins contained in the leaves. Leaf color from green to copper red, black tea-specific colors. When the tea liquid membrane got damaged, the polyphenols, amino acids and other substances of the vacuole are gradually being oxidized, while the catechin oxidation, so that part of the chemical substances in the leaves to produce black tea-specific color and flavor quality.

The above is the basic meaning of fermentation of Chinese tea. However, due to the variety of Chinese tea, the processing technology and the system of law are rich and colorful, the definition of quality is different. In some tea production and quality formation, in addition to the above-mentioned fermentation in the sense of biological oxidation of its own enzymatic reaction, there are also microorganisms involved in some areas. For example, Pu'er tea and matcha fermentation process, in addition to enzymatic action, but also the participation of microorganisms. After separation studies, the main microorganisms are Aspergillus niger, Aspergillus oryzae, Aspergillus clavatus, Aspergillus kawaii, Rhizopus, lactic acid bacteria and yeast. Nevertheless, we still need to clearly distinguish the microorganisms involved in the fermentation and the fermentation of the sense of biological oxidation - otherwise, the ambiguity of concept easily leads to a misunderstanding of the formation of tea quality mechanism.