Why Does Cooked Tea Become Sour?

The acidity of cooked tea is generally caused by improper processing during the fermentation process.

The “sour taste” in the pile is a common phenomenon in the fermentation of cooked tea. Usually, the acidity is smelled 4 to 5 days after the start of fermentation, which indicates that a violent chemical reaction has occurred inside the tea pile. The stage characteristics of Pu-erh tea fermentation. In the middle and late stages of the pile, many low-boiling aroma substances with a pungent odor are decomposed in large quantities. If the pile has too much water, poor gas permeability and low temperature, it will produce anaerobic respiration, various anaerobic bacteria, When a large amount of spoilage bacteria is produced, it is easy to make the tea sour and the bottom of the leaves soft and viscous, so that the “acid” gas substance is difficult to completely eliminate, and the loose tea after the pile is bound to have a sour taste.
The sour substances in cooked tea are mainly various organic acid compounds such as citric acid, malic acid, succinic acid, ascorbic acid, gallic acid and free acidic amino acids. The formation of these substances is closely related to the role of microorganisms. The most visible to the naked eye during the stacking process is the dominant microbial strain Aspergillus niger. Aspergillus niger produces a series of acidic substances such as citric acid during the stacking process. Of course, other microorganisms also produce acid. If the process is not properly treated during the fermentation process, it can not effectively discharge acid, which will cause Pu-erh tea to “sour”.

It is also prone to sour taste when fermented with a higher level of tender tea. This problem is likely to occur with single buds, one bud and one leaf. These high-grade and high-prevalence tea fermentations must pay special attention to controlling the amount of water and gas permeability, otherwise the sour taste is difficult to exclude. In the fermentation plant accompanied by the growth of white mold black mold, a large amount of sour taste will be produced, and the acidity will be slowly disappeared in the middle and late stages of the acid-extracting process control.
Acidified cooked tea is usually dehydrated by means of a second pile fermentation. Generally, the moisture content of the sour mature tea is regained to 25% to 30%, and the high temperature is used to discharge the acid at a temperature of 50 degrees or more and 60 degrees or less. After the second fermentation of cooked tea, the loss will increase and the initial water taste will increase. Generally, small quantities of sour tea are acid-removed by adjusting the storage process.

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