Tea can actually be stored for long periods, but it remains an agricultural product with a shelf life. Within the shelf life, the main factors causing tea deterioration are: 1. Light, 2. Temperature, 3. Tea moisture content, 4. Air humidity, 5. Oxygen, 6. Microorganisms, 7. Odor contamination. Therefore, for most teas, the key preservation points are protection from light, constant temperature, dryness, and sealed oxygen-free storage.
Impact of Humidity
Chlorophyll content is high in tender buds and leaves, and under light and heat conditions, it easily loses green color and turns brown. Tea polyphenols are prone to oxidation during storage, leading to brown discoloration. Vitamin C is an important component that gives tea its nutritional value, and its content is closely related to tea quality. Vitamin C is also easily oxidized and difficult to preserve. When vitamin C is oxidized, it not only reduces the nutritional value of tea but also turns the tea brown, causing the taste to lose its freshness.
When the moisture content in tea is too low, the tea easily ages and deteriorates. When the moisture content in tea is about 3%, it is easy to preserve. When the tea moisture content exceeds 6%, or when the air humidity is above 60%, the tea's color turns brown and dark, and the tea quality deteriorates. The moisture content of finished tea should be controlled between 3% and 6%. If it exceeds 6%, it should be re-fired and dried.
Impact of Temperature
Higher temperatures accelerate tea aging.
During tea storage, for every 1°C increase in temperature, the browning rate accelerates by 3-5 times. Storage below 10°C can inhibit tea browning. Refrigeration at -20°C can almost completely prevent tea aging and deterioration.
Impact of Oxygen
If tea is stored improperly and oxygen enters, it will accelerate the oxidation process of the tea, affecting its quality.
Impact of Light
Light is a form of energy. When tea is exposed to light, it causes chlorophyll to decompose and fade. During storage, exposure to light affects tea quality and can even make it lose its drinking value.