Heavy rain in the south, hot in the north, and the recent weather really responds to a sentence: drought and drought, waterlogging and drowning!
News related to extreme drought and flooding, such as "Henan farmers water 60 acres of land, Guangdong residents have not seen the sun for a week", "Shandong Yimeng Mountain fruit farmers kneel on the ground to pray for rain" and other news related to extreme drought and flood have aroused heated discussions.
With the continuous rain in the south and the high temperature in the north, the frequent flood prevention warnings on one side and the drought on the other side have caused the crops on the other side, and the phenomenon of "flooding in the south and drought in the north" has aggravated and has had a significant impact on social life and the ecological environment.
The difference in extreme climate brought about by different regions will also lead to differences in tea storage methods between the north and the south. It is the 618 shopping festival, and I believe that many tea lovers have hoarded their favorite tea and are ready to save it.
So, under the flood in the south and drought in the north, what do tea lovers in the north and south need to pay attention to when storing tea? Let's take a look at how to store it so as not to ruin the tea~
Key points of tea storage in the south
Recently, the rain or extremely strong convective weather in Jiangnan, South China, Yunnan, Guizhou and other places has brought a lot of moisture, which has brought a lot of trouble to the storage of tea.
Generally speaking, the quality of tea leaves with a water content of less than 6% is relatively stable, and if the water content exceeds 8%, it is easy to age; When the water content of tea leaves > 12%, it is very likely to become moldy and deteriorate.
In China, the comparative study of vitamin C and polyphenols was carried out by storing roasted green tea under different humidity conditions (high humidity 80%~90%RH, ambient humidity 40%~50%RH, low humidity 20%~30%RH).
In this experiment, a colorimeter was used to determine the color of the raw materials (L: brightness, a: red and green bias of colored substances, b: yellow and blue bias of colored substances, and E: color difference between the sample and the proofreading whiteboard).
As can be seen from the above figure, in the environment with a relative humidity of up to 80%~90%, the oxidation rate of tea polyphenols is very fast under the influence of high humidity, showing a significant downward trend, and the vitamin C content in tea increases and fluctuates greatly.
With the extension of storage days, the L and a values in the color of green tea in the high humidity environment increased significantly, and the b and E values decreased significantly, and the color and luster of the tea were significantly deepened and the aroma was significantly lightened in the sensory environment.
Under the ambient humidity, the tea polyphenols and vitamins showed a slight downward trend, the color of the tea did not change significantly, and the aroma became slightly lighter. However, the decrease of tea polyphenols in the low humidity environment was small, and the decrease of vitamin C was obvious.
This indicates that the low humidity and dry environment will promote the oxidation of vitamin C, but will inhibit the oxidation of tea polyphenols, even if the storage time increases, the overall color and aroma of tea have no obvious change, and the quality is stable.
It can be seen that storage in a low-humidity environment is more conducive to the quality of tea, so tea lovers in the south must focus on moisture-proof when storing tea during this period! Specifically, you can start from the following aspects:
1. Store off the ground and off the wall
When storing tea in the humid south, the first thing to pay attention to is that the tea leaves should not be placed directly close to the ground or next to the wall, so as to avoid the moisture of the ground and the wall and cause the stored tea leaves to become damp and cause mildew and deterioration.
Therefore, whether it is a single cake, a whole or a whole piece of tea, it is recommended that southern tea lovers at least set up a tea storage empty rack at least 10~20 cm from the ground and the wall to avoid dampness of tea and facilitate transformation.
In addition, it should be reminded that the room where the tea is stored is best not located on the first floor, because the waterlogging caused by the continuous rainstorm in the south cannot be discharged in time, and it is likely to pour into the lower floors, so that the stored tea leaves "bubble".
2. Seal and preserve the tea leaves
No matter what kind of tea leaves, it is best not to expose the tea leaves directly to the air, and it is recommended to seal the package before storing it. First, it can effectively isolate the moisture in the air and avoid oxidation of tea leaves due to moisture.
In addition, tea has a loose and porous structure, easy to absorb peculiar smells, the second important role of sealing tea is to isolate peculiar smells, ensure that the tea does not inhale other peculiar odors, and the taste is pure.
Due to the recent rainfall in the south and the high humidity in the air, it is recommended to use the common three-layer packaging method, that is, aluminum bags, plastic bags, cartons, etc. to strengthen the sealing of tea leaves, which can effectively avoid moisture.
3. Don't open the box frequently
In the rainy season, some southern tea lovers are always worried about whether the tea will be damp and moldy after sealing the tea, so they can't help but frequently open the box for inspection, which is really a good intention.
Even if the time for each unpacking inspection is not long, it is difficult to avoid the moisture in the air from invading the stored tea leaves, and the more inspections are likely to increase the possibility of the tea being damp.
As a result, the tea has a series of undesirable phenomena such as soft texture, lighter aroma, mildew and smelly, so after confirming that the tea has been sealed and preserved, it is best to reduce unpacking inspection or taking tea to drink.
4. Ventilation of tea storage space
Under the waterlogging in the south, the humidity in the air is inevitably high, in addition to sealing the tea leaves, you can also put a hygrometer in the tea storage space to monitor the ambient humidity at any time for easy adjustment.
When the rainstorm comes, close the doors and windows in time to avoid excessive humidity in the tea storage space, and then open the windows for proper ventilation after the rain stops.
In addition, you can also place some bamboo charcoal to effectively absorb odors while dehumidifying. Wait until it rains and then close the doors and windows in time to avoid a large amount of water vapor from the rainfall from invading the tea storage space.
Key points of tea storage in the north
The drought situation in the north continues to develop, and some areas such as North China, Huanghuai, and Jianghuai have been affected by drought, and many provinces have launched drought prevention measures, and the temperature of the storage environment will also affect the quality of tea.
In this regard, the relevant scientific experiments set up three low temperatures of 5 °C, -10 °C and -20 °C to store Xinyang Maojian tea, and then took it out at the 0th, 30th, 90th and 210th days of storage and compensated it with a hot air temperature of 35 °C for 10 minutes for determination and analysis.
As shown in the figure above, the moisture content of Xinyang Maojian tea was positively correlated with the storage time, and the moisture content was up to 111.45% when stored at 5°C for 210 days, while the moisture content decreased by about 30~50% after temperature compensation in the middle and late stages.
These results indicated that the temperature compensation treatment could effectively inhibit the increase of moisture content during storage of Xinyang Maojian tea during long-term storage at higher temperatures. However, when stored at low temperature, temperature had no significant effect on the moisture content of Maojian tea.
In addition, low temperature (-10°C, -20°C) could effectively inhibit the decrease of chlorophyll content, and the best effect was at -10°C, with a decrease of only 24.97%, while the decrease of chlorophyll at 5°C was as high as 28.18%.
After temperature compensation treatment, the chlorophyll loss was as low as 19.59% at -10°C, and the chlorophyll loss could be significantly reduced by 28.57% at 5°C. It can be seen that the combination of low temperature and temperature compensation is more conducive to the retention of chlorophyll.
Chlorophyll is the main pigment component that constitutes the color, soup color and leaf bottom of dried green tea such as Xinyang Maojian, and the more its content is retained, the smaller the degree of browning of the tea leaves, and the fresher and more tender the color is as before.
It can be seen that low-temperature storage is more conducive to the color and freshness of green tea, and temperature compensation during long-term storage is conducive to reducing the moisture content.
1. Avoid direct sunlight
As the temperature in many places in the north breaks the extreme, the damage of high temperature to tea is irreversible! Because the chlorophyll in tea will accelerate the decomposition at high temperatures, resulting in browning and affecting the freshness.
From the above scientific experiments, it can be seen that storing tea at low temperature can better inhibit the process of tea browning. For every 10°C increase in temperature, the rate of browning of tea leaves increases by 3-5 times.
Therefore, the storage of tea in the north, especially the storage of green tea, yellow tea and new white tea with a fresh taste, must avoid direct sunlight, high temperature storage of tea leaves, and the container for storing tea should be protected from light!
2. Increase humidity appropriately
The continuous high temperature in the north is not enough humidity in the air, and some means can be artificially used to increase the humidity when storing tea. For example, use a humidifier in the tea storage space, or put a few basins of water to adjust the humidity of the tea storage.
However, we must pay attention to changing the water frequently to avoid the smell of water that has been placed for too long, so that the tea will absorb the odor and cause peculiar smells, which will affect the quality of later storage, and the gains outweigh the losses.
In order to avoid excessive humidity regulation, tea lovers in the north can also use a hygrometer to monitor at any time, and tea also needs to pay attention to details such as sealing, storage off the ground and off the wall.
3. Store tea in the refrigerator reasonably
In the north where there is a shortage of water and aridity, you can consider using a refrigerator to store tea, and storing tea in a refrigerator with a lower temperature can reduce the degree of oxidation and browning of tea and lock in the freshness of tea.
However, not all of the six major tea categories pay attention to freshness, and there are also tea leaves that are older and better, and the pursuit of old rhyme, not all tea is suitable for refrigerator storage, and tea lovers in the north should pay attention to reasonable control.
Generally, fresh and tender green tea, yellow tea, high-grade black tea, etc. can be stored in the refrigerator at low temperature, if you plan to drink it in a short period of time, you can refrigerate it at 0~5 °C, if it is stored for more than half a year, it is best to freeze it in the refrigerator.
The aroma of oolong tea with a low degree of fermentation is easy to oxidize when stored at room temperature, and the typical aroma of fragrant Tieguanyin, Zhangping Narcissus, etc., which is more conducive to maintaining high fragrance and sweetness when stored in the refrigerator.
This is also applicable to the storage of tea in the south, the refrigerator storage of tea must consider the characteristics of tea, roasted oolong tea, post-fermented black tea, the older the better the old white tea, Pu'er tea, etc. are not suitable for refrigerator storage.
In summary, affected by the extreme weather of waterlogging in the south and drought in the north, the storage of tea in the south is the first priority to prevent moisture, while the storage of tea in the north should be protected from light and avoid high temperatures.
In fact, as long as it is clear what tea is most afraid of, regardless of the north and south regions, if you want to store good tea, you must pay attention to the following details of tea storage:
Tea is most afraid of moisture, generally speaking, the humidity of the tea storage space is best not to exceed 70%, otherwise the tea will appear mildew, deterioration and sour due to moisture absorption, and the taste of the tea will be poor.
In addition to accelerating the browning process of tea, high temperature will also decompose and destroy amino acids, sugars, vitamins and aromatic substances in tea, reducing the sensory quality of tea.
Here, by the way, the temperature and humidity of different types of tea stored as specified in the National Standard of the People's Republic of China GB/T 30375-2013 are attached as shown in the figure below:
Excessive exposure to oxygen is easy to volatilize chlorophyll, aldehydes, esters, vitamin C, aromatic substances, etc. in tea, resulting in color browning, lightening of aroma, and reduction of nutritional value.
The chlorophyll in tea will oxidize and decompose with esters into magnesium chlorophyll in the ultraviolet rays under strong sunlight, which will lose a certain color and flavor and produce a sun-dried taste.
Tea contains highly absorbable odor polymer palmitase and terpene compounds, once the odor is absorbed, it cannot be removed, which is also one of the important reasons for the sealed preservation of most tea.
Everyone must pay more attention to the details when storing tea, so as not to waste good tea! Regarding tea storage, what experience do tea lovers in different regions have to say? Welcome to leave a message in the comment area to share and discuss~
Note: Some of the pictures in the article are from the Internet, if there is any infringement, please contact to delete.
Resources:
[1] "The Effect of Different Temperature and Humidity and Packaging Conditions on the Storage of Dried Tea Products", Zhu Danshi and Zhang Min (College of Food Science, Jiangnan University, Wuxi, Jiangsu, 214036);
[2] "Effect of Temperature Compensation Treatment on the Quality of Xinyang Maojian Tea during Storage", Xingxu Jiang, Long Chen, Yangyang Zhang, Rongrong Wang, Kaihua Liu, Yibing Hu (Xinyang Agriculture and Forestry University, Xinyang 464000, Henan, China; Henan Key Laboratory of Comprehensive Development of Tea Resources, Xinyang 464000, Henan, China);