In life, some tea lovers rarely pay attention to the shelf life on the packaging when storing tea, thinking that all teas are suitable for long-term storage. In fact, not all teas are more fragrant as they age. The reason why teas such as Pu'er tea are more fragrant as they age is because they have unique craftsmanship to support them. Compared with green tea with simple production processes, it is not suitable for long-term storage.
After summer, many people take green tea out of the refrigerator, thinking that the weather is getting cooler and they can drink it slowly. This is actually a big misunderstanding, because green tea taken out of the refrigerator is not suitable for long-term storage and should be drunk as soon as possible.
As a non-fermented tea, green tea focuses on the word "fresh" in taste, and has relatively strict requirements on storage conditions: high temperature will accelerate the degradation of chlorophyll in green tea and reduce nutritional value; strong light will cause photochemical reactions of plant pigments and lipids in green tea, producing odors; if it is damp, it will accelerate deterioration and even mildew.
According to our tea artist, tea also has a shelf life, but the shelf life varies depending on the type of tea. Generally, the shelf life of green tea is 18 months. In order to maintain the quality of green tea, it must be sealed, light-proof, moisture-proof, and low-temperature during storage, otherwise the tea will quickly oxidize and deteriorate. Generally speaking, green tea can be stored for one to one and a half years at a low temperature of 0-5℃, and its color, aroma, and taste will not change much. If it is stored for a long time at room temperature, even if the sealing measures are done well, it cannot completely prevent it from contacting with the air, and the tea will lose its original fresh taste due to oxidation. Therefore, green tea should not be stored for a long time to avoid the best tasting period.
1. Color
Chlorophyll is an important component in the formation of green tea color. The chlorophyll in green tea is very unstable. Under the action of water, light and temperature during storage, it is easy to undergo magnesium removal reaction. When the proportion of magnesium removal chlorophyll exceeds 70%, the color of the tea will obviously darken and turn brown.
Vitamin C is also an important component of tea with nutritional value, and its content is closely related to the quality of tea. Vitamin C is also a substance that is easily oxidized. The higher the green tea, the higher its content and the more difficult it is to preserve. After being oxidized, vitamin C generates deoxyvitamin C, which interacts with amino acids to generate aminocarbonyl, which not only reduces the nutritional value of tea, but also makes the color brown, and the taste also loses its freshness.
2. Aroma
The "new tea aroma" of green tea will decrease significantly during storage. After two months of storage, it will decrease by more than 30 to 40 percent. It will also produce some substances that are not in new tea, with a grassy and oily smell. At the same time, carotene is also easily oxidized to produce new compounds, affecting the aroma.
3. Tea soup quality
The quality of green tea soup is mainly related to tea polyphenols and amino acids. Tea polyphenols have the closest relationship with the taste and soup color of tea. Its content determines the taste concentration of the tea soup.
In green tea, the retention of tea polyphenols is relatively large, and it is also easy to oxidize during storage, generating compounds, causing the color to turn brown. At the same time, these substances can also react with amino acids in one step, causing the taste to deteriorate.
