The Storage of Tea

The Storage of Tea

1. What are the major factors influencing the quality change of tea during its storage?

During the storage of tea, substances like tea polyphenols, amino acids, lipids, vitamin C, and chlorophyll are very likely to be oxidized and degraded, thus causing changes in sensory qualities, including the color, aroma, and taste of tea. These changes are mainly subject to factors such as water content in tea, ambient temperature, humidity, abundance of oxygen and light intensity. Higher water content in tea, higher ambient humidity and temperature lead to a greater loss of quality. Abundant oxygen and light exposure can accelerate the oxidation of various quality substances in tea and lead to a faster loss of quality. In addition, due to its high absorptivity, tea is very likely to absorb peculiar smells. So odors must be avoided in the storage environment of tea.

2. How to store tea at home?

There are three ways to store tea at home.

①. Storing tea in a container or tea caddy: Use an iron box, glass bottle or rice jar that can be sealed and of appropriate size to store tea. Place some lime or silica-gel as desiccant at the bottom, wrap tea with craft paper or into small packs and place them on top of the desiccant, which should be replaced every once in a while.

②. Storing in small sachets: Store tea in the plastic compound with an effective sealing option, e.g., aluminum foil add a small amount of desiccant and seal die sachet before putting them into an iron caddy or paper caddy.

③. Storing in a refrigerator: Taking advantage of the km temperature to maintain a stable quality of tea can be an economical and effective storage method. However, when using household refrigerators, given that tea can absorb smells and moisture quite easily, it is particularly important to seal the tea in packages so as to prevent the tea from absorbing smells from other foods in the refrigerator.

3. Is tea drinkable when it gets damp?

It depends on the time of exposure to a damp condition and how damp it becomes. If the period is short and the tea is not too damp and has not deteriorated, it would be helpful to immediately dry the tea (by measures such as drying and frying) to remove excess water. The tea is still drinkable, but the quality may be compromised, for example, the brew may become yellow and less fragrant. If the period is too long or when the tea becomes too damp, the tea may be deteriorated or even mildewed. Then the tea becomes undrinkable and should be thrown away.

4. Do different teas require different storage environments?

Different teas need to be stored in different environments according to their own characteristics. It is recommended to store non-fermented green tea, light-fermented South Fujian Oolong tea, Taiwan Oolong tea under refrigeration. An appropriate amount of tea should taken out from storage, and when it reaches room , temperature it can be brewed to drink. Like black tea, yellow tea, Guangdong Oolong tea, and North Fujian Oolong are heavily fermented or baked. It is recommended to seal them in an environment at room temperature and protect them from the light. As for white tea, dark tea and other teas that need to be post-matured, they should be wrapped in cotton paper and stored at room temperature and away from light. Moreover, the ambient humidity should not be too high; otherwise, the tea leaves are easy to mildew.

5. Why is the tea quality easily affected?

The color, aroma, and taste of teas are easily affected and even deteriorated by the conditions of the external environment in the process of storage, transportation, and consumption. There are three main reasons. First, the loose and porous structure of teas endows them with strong adsorption ability. Second, the rich polyphenols in the tea are easily oxidized. Third, the main substances of the color, aroma and odor in the tea are easily oxidized and degraded.

6. How should premium green teas be stored?

Premium green teas are very susceptible to quality loss during their storage, and they need very particular storage conditions. The storage, transportation and consumption of premium green teas involve three major processes: large-scale storage, retail tea storage, and household storage.

① Warehouse for large-scale storage. Tea in large quantities is usually stored in dedicated cold storage units or warehouses that are dry and odorless. With a temperature between 2-8℃ and a relative humidity below 60%,the quality of tea can be maintained stable for a storage period of 8-10 months within the warehouse.

② Retail tea storage. Retail tea products in small packages should be stored in compound bags with excellent sealing performance, e.g., aluminum foil bags. Fresh-keeping techniques should be taken. These can be desiccant or modified-atmosphere technologies such as oxygen removal or nitrogen filling. When possible, retail tea can be stored in small refrigerators, which has better storage effects.

③ Household storage of premium tea. These teas can be stored in refrigerators or freezers and should be closely sealed and kept away from other odorous foods.

7. How to judge whether the tea is deteriorated or not?

The deterioration of tea means a significant change in quality, which causes obvious flavor abnormalities. Whether there is a deterioration or not is usually judged by the color, aroma and taste of the tea.

①. Observing the color: whether there is a significant change in the color of tea. Green tea turns from emerald green to yellow and dark. Black tea and other teas with a higher fermentation degree are covered with a gray layer.

②. Smelling the aroma: the deteriorated tea becomes much less aromatic and lacks authentic smell. The aroma becomes light and difficult to be distinguished. Sometimes there are even unpleasant smells such as stale or rancid odors.

③. Tasting the tea: the deteriorated tea has a much less fresh or pure taste. For example, green tea may lose its original freshness, and black tea may become sour.

8. How is the new tea and aged tea distinguished?

Aged tea refers to the tea produced in the previous production year and before. Due to the long storage time, the contents of the tea are oxidized for a long time. As a result, the quality of the tea is reduced and the aroma is lightened. These changes help to identify the aged tea from the fresh tea. The fresh green tea is green. lustrous, fragrant and mellow, and the color of the tea brew is clear. Yet aged tea is yellow and not as fresh as the new tea, and has a little scent. If the storage conditions are not good, the aged tea should have a stale taste and the infusion would be yellowish. The fresh black tea is black and bloom, fragrant and mellow. The infusion is red and shiny, and the steeped leaves are red and bright. However, the aged black tea in poor storage is dark in color with little aroma, bland or stale taste. The color of the infusion of the aged is dull and not as bright as fresh tea. And the aged steeped tea leaves would be in dark red and unable to stretch.

9. What are the best times for consuming different types of tea?

The best-before date varies for different types of tea. Non-fermented green tea, light-fermented southern Fujian Oolong tea, and Taiwan Oolong tea should be consumed during the year of production. For black tea, yellow tea, heavy fermented or baked Guangdong Oolong, northern Fujian Oolong, etc., it is recommended to drink them within 2 to 3 years after production. White tea and dark tea that need to go through the process of maturity transition can be stored for a period of time. The quality of Pu'er tea can be obviously improved after storage,so it is recommended to drink Pu'er tea after a period of torage. Take Pu'er tea as an example, raw Pu'er tea can be stored for 15-20 years under suitable conditions and the taste would be better. It is advisable to store post-fermented Pu'er tea for 5-8 years. It is not recommended to store the tea for as long as possible. After a long period of storage, the flavor substances in the tea are lost and the taste becomes pale. For example, the Qing Dynasty tribute tea in the Forbidden City would have only a mild aroma and taste after nearly two hundred years of storage.

10. How is the Pu'er tea stored?

One should be aware of the influence of oxygen content, temperature, light and humidity on Pu'er tea during storage.

①. Air: Pu'er tea should be stored with circulating air but not in a draught. In addition, it should be protected from odors such as odors in kitchens and the industrial environment.

②. Temperature: The storage temperature of Pu'er tea should be neither too high nor too low. It is advisable to store it at the local room temperature. It is not necessary to create an environment with a certain temperature. The normal indoor temperature, ideally between20℃ and 30℃, would be suitable for the storage. Too high temperatures accelerate the fermentation and acidification of the tea.

③. Light: Light provides the energy that changes the chemical composition inside the tea. If the tea leaves are exposed to the sun for a day, the color and taste of the tea change significantly, thus losing its original flavor. Therefore,tea must be protected from light.

④. Humidity: An excessively dry environment can slow down the aging of Pu'er tea. In a dry environment, a small glass of water can be placed next to the tea to increase the humidity in the air. However, a too humid environment can lead to rapid changes in Pu'er tea. One of he common changes is "mildewing",which can render the Pu'er tea undrinkable. It is recommended to maintain the humidity at around 75%. In coastal areas, the humidity is higher than 75% in the rainy season due to the warm maritime climate. Thus, timely ventilation for distributing moisture is necessary during storage.

11. How is the white tea stored?

After storage, the color of white tea becomes darker and the taste of the brew becomes mellower and thus the tea is loved by many consumers. There are four requirements for the storage of white tea. First, if the white tea is stored for a long time, its moisture content should be maintained below 5%. Second, the storage environment should be dry, free of odor, and the humidity should be below 60%. If the room for storage has a cement floor, the soleplate should be supported by wooden frames. Third, white tea should be stored at low temperature and kept away from light since the chemical changes of the components in the tea and aging process are accelerated if the temperature is high and photochemical reactions of the components in the tea result in loss of the original flavor. Do not open the package during storage because the air entering into the package can accelerate the oxidation of the tea.

12. Does raw Pu'er tea become ripe Pu'er tea after storage?

Raw pu'er tea does not become ripe Pu'er tea after storage under the natural condition. Raw Pu'er tea refers to the preyed lea made of sun-dried semi-finished tea leaves of Yunnan large-leaf (Daye) species. The color of the dried tea is blackish green. Ripe Pu'er tea is also made of sun-dried semi-finished tea leaves of Yunnan large-leaf species but already go through the process of pile-fermentation among other manual processing. The color of the ripe Pu'er tea is dark brown. In brief, ripe Pu'er tea is produced by manual processing of pile-fermentation, while raw Pu'er tea has not gone through this process. Raw Pu'er tea may have a change in quality during storage but it is a natural aging process. Raw Pu'er tea will not become ripe Pu’er tea in the end. They have a big difference in their taste.

13. How many materials are there for the package of tea?

Tea packaging refers to the containers or materials used to protect the quality, sanitation and safety of tea, extend its shelf life, and facilitate its transportation, weighing, preservation, display and sales. There are a variety of packages and materials for tea. Packaging materials include cardboard, craft paper, white cardboard, plastic film, aluminum foil compound film, glass, etc. Containers include iron caddy, paper caddy, aluminum caddy, bamboo or wooden container, porcelain jar, tin caddy, etc. The packaging of tea plays an important role in keeping the quality of tea in the process of processing, marketing, storage and distribution, and preventing and reducing the deterioration of the color, aroma, taste and nutrition of the tea.