What is Tea Fermentation and What is The Process?

What is the fermentation of tea?

Tea enthusiasts know that tea fermentation is very important during the production process. Aside from green tea, other types of tea have varying degrees of fermentation. Examples include white tea with slight fermentation, black tea as post-fermented tea, and oolong tea as semi-fermented.

And fermentation precisely occurs because it is a process of biological oxidation. In the industrial field, fermentation refers to the industrial production in which people rely on the life activities of microorganisms. What we commonly refer to as tea fermentation involves 3 types of oxidation reactions around tea polyphenols:

  • Polyphenol-promoted oxidation reaction,
  • Non-enzymatic automatic oxidation reaction (damp heat reaction)
  • Microbial enzyme-promoted oxidation reaction.

No matter what kind of tea fermentation it is, the oxidation products are tea pigments, including theaflavins, rubins, and brownies. For different types of tea, the degree of fermentation varies, and accordingly, the proportion of these 3 types of tea pigment is not the same, which is manifested in the tea soup as the difference in lightness darkness, and depth.

What are the different levels of tea fermentation?

In terms of degree and process, the other 5 types of fermented tea can be divided into mild fermentation (yellow tea, white tea), semi-fermentation (oolong tea), full fermentation (black tea), and post-fermentation (black tea). Here below is the definition of each level.

tea fermentation and post fermented tea

Micro fermentation: the degree of fermentation is about 5% – 10%, natural and slight fermentation occurs in the process of making, such as white tea.

Light fermentation: the degree of fermentation is about 10% – 20%, in hot and humid conditions, automatic fermentation, and slightly light fermentation, such as in yellow tea.

Semi-fermentation: the degree of fermentation is about 15% – 50%, and then the fermentation is killed to stop the fermentation suddenly, such as in oolong tea.

Full fermentation: the fermentation degree is about 70% – 80%. The tea cells are damaged by rolling, and the enzyme can play a full role in full fermentation, such as black tea.

What is Tea Fermentation and What is The Process

Post-fermentation: fermentation degree of 100%, with the help of external microorganisms, under the comprehensive effect of enzymes, microorganisms, and damp heat, the fermentation is complete, such as in black tea.

The Fermentation of Black Tea

It can also be simpler, completely standing in the perspective of the process, divided into pre-fermentation and post-fermentation.

After that, the so-called “end of fermentation” can be understood as “the end of fermentation” at the same time.

What is Tea Fermentation and What is The Process

The corresponding “post-fermentation” is the primary processing fermentation, which is still in fermentation after the initial preparation and continues to ferment in the water storage, which has the characteristics of the whole process and continuity.

The former occurred in the process of initial production; The latter, whether it is the initial preparation, or after the formation of finished tea based on Maocha, is happening. Therefore, with the “primary production” as the node, one only has “early fermentation”, while the other has “pre-fermentation and post-fermentation”.

The so-called “pre-fermentation” and “post-fermentation” are both abbreviated.

There are four types of pre-fermented tea, yellow, white, green, and red, with different levels of fermentation, but all of them are fixed. Therefore, there is a distinction between micro fermentation, semi-fermentation, and full fermentation.

Post-fermentation tea, fermentation is dynamic, in the development from low to high; In a long-term span of years, it includes all the evolution of micro (or light) fermentation, semi-fermentation, and full fermentation.

What is Tea Fermentation and What is The Process

Everything will flourish and decline. The quality of all kinds of tea, therefore, will decline from the “best” of its apex to worthless at a certain point in time. The premise here is to keep it properly, otherwise “deterioration” will accelerate.

What is Tea Fermentation and What is The Process

Generally, pre-fermented tea also includes nonfermented green tea. Due to the good quality characteristics formed in the processing, it is not suitable to keep it for a long time and drink it within the shelf life;

Then fermented tea, their quality optimization, needs to be gradually achieved in the long-term storage, will be relatively “better and better”, but beyond a certain period, the same “worse and worse”.

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