Collection of the hottest tea preservation techniq

2022-08-13
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Tea preservation technology collection

preservation of tea

tea is a dry food with a long shelf life; However, the "shape, color, aroma and taste" that affect the price of tea will change over time

factors of tea quality change: internal factors: water content of tea itself

external factors: light, temperature, oxygen, odor

due to the influence of the above factors, the changes of polyphenols in tea - "aging" are as follows:

chlorophyll: it is an important component that affects the appearance and color of tea, and it will browning due to high temperature and ultraviolet radiation. Green tea and light fermented light roasted tea have the greatest impact

vitamin C: it will be reduced due to oxidation. The water content in tea is more than 6%, or high temperature and sunshine will greatly reduce vitamin C; In addition to the brown color of tea soup, the taste is not fresh

catechins: automatically oxidize due to moisture absorption, which makes the taste of tea weak and has a turbid aging taste

theaflavins and thearubins: the brightness and freshness of tea soup are affected by oxidation

fatty acids and carotenes: sour taste is produced due to the combination of high temperature and oxygen in the air

amino acids: the combination of oxidation and tea polyphenols affects the freshness and sweetness of tea soup. Green tea is the most influential

aroma: decreased due to prolonged storage time

key: control water content, avoid direct sunlight, keep fresh at low temperature, and deoxidize vacuum packaging. Nw

outer packaging material: light tight plastic bag, metal can or paper can, aluminum foil bag that can isolate the air.] N{

family preservation: tea is a product that can be stored for a long time. As long as it is properly preserved, such as "keep dry, avoid inhaling peculiar smell, avoid direct sunlight", it can be stored for a long time. Generally, the storage period is indicated as two years. If it exceeds the time limit, as long as it is not moldy, and after proper baking, the aged tea soup still has a different taste, except that it does not have the original "fragrance" taste.

the value of high priced tea winning the competition is "aroma" Don't be reluctant to drink; It will lose its original flavor after long-term storage. Of course, based on the nutritional value of tea, it is debatable whether it is necessary to spend a lot of money to buy back high priced competition tea

aged tea: tea has qualitative changes due to improper storage, but if tea merchants store tea in a proper environment, although the fragrance and sensitivity of tea soup will be reduced due to time factors, the post fermentation effect of polyphenols due to continuous oxidative polymerization will reduce the bitterness of caffeine in tea and make the tea soup more mellow. The key to avoid deterioration is to keep dry and let the polyphenols in tea evolve slowly and gradually, Its effect on human body is the same as Pu'er tea under the trend of regular production and consumption upgrading. It has folk handed down effects such as reducing blood fat, losing weight, lowering blood sugar, warming the stomach, sobering up, generating saliva and quenching thirst, which is worthy of further research and promotion

chemical changes and preservation methods of tea during storage

during the storage, transportation and marketing of tea, it is easy to be affected by the surrounding environmental factors. A series of complex chemical reactions occur with the quality chemical components, and various substances that are not conducive to the color, aroma and taste of tea are produced, resulting in the aging and deterioration of tea. The sensory expression of aging and deterioration of tea is that the color of tea changes from fresh to dry, the color of soup changes from bright to dark, the taste changes from sweet to light, and the aroma changes from heavy to light. This is because most of the chemical components corresponding to the sensory quality of color, aroma and taste, such as polyphenols, amino acids, lipids, pigments, aromatic substances and other organic substances, have unstable properties, and are very prone to automatic oxidation under the action of oxygen in the air, which will deteriorate the quality of tea and lose the original color, aroma and taste. Next, by understanding the main chemical components of tea and what external environmental factors affect them, we can take appropriate measures and means in the storage, transportation and marketing of tea to achieve the purpose of tea preservation

I. main chemical components of tea

1. Polyphenols_

polyphenols and catechins are the main components of tea taste. They coordinate and cooperate with amino acids, sugars and other components to make the tea taste mellow, fresh and astringent. However, polyphenols, especially catechin, which accounts for about 70% of the total amount of tea polyphenols, are easy to oxidize automatically during storage. Although the speed of this oxidation is slow, not as intense and rapid as enzyme oxidation, but after long-term storage, this change is very significant, especially in the case of high water content of tea, high storage temperature and high air humidity, the rate of decline of polyphenols is very significant

the change path of catechin in polyphenols is dehydrogenation to form quinone, and further oxidative polymerization to form Brown substances. Catechin materials are also widely used in aerospace, fire safety, military equipment and other fields. The intermediates in the oxidation process also combine with amino acids, proteins, etc. to form dark high polymer compounds, which destroys the coordination of the taste structure of tea soup, makes the taste of tea soup become thin and lack convergence and freshness, and the color of tea soup becomes darker and darker, gradually transforming from the inherent natural color to orange, red and brown

according to the experimental results of green tea stored for 12 months: during the storage period, the polyphenols content of tea showed a significant downward trend, from 23.71% before storage to 21.12%, with a decrease of 10.92%. Catechin, as the main body of polyphenols, decreased from 102.71mg/g to 61.64mg/g during storage, with a decrease of 39.99%. The reduction range and oxidation rate of polyphenols during storage are also related to the moisture content of tea and air humidity. After 12 months of storage of broken black tea, thearubicin increased from 6.6% to 10.10%, with an increase of 53.03%. Thearubicin is brown, which is the main component of dark tea soup. The content is too high, the taste is light, the soup is dark, and the shadow is 3 Measuring range: 2% of the measuring range ⑴ 00% of the quality of xiangblack tea

2. Amino acids

amino acids are important flavor substances of tea and are very important to the quality of tea. The changes during storage are very intense. Amino acids can combine with the automatic oxide quinones of tea polyphenols to form dark polymers, which affect the color of green tea and the brightness of tea soup; In black tea, amino acids also interact with theaflavins and thearubins to form dark polymers. In addition, amino acids will decompose and transform themselves under certain temperature and humidity conditions. For example, theanine, which plays a major role in the freshness of tea soup, is easy to hydrolyze to produce ethylamine and glutamic acid, thus reducing the content of free amino acids

theanine is the main amino acid in free amino acids, which has special significance for the taste quality of tea soup. During storage, it showed a straight-line downward trend, and its content decreased from 770.18mg/100g before storage to 404mg/100g, with a decrease of 47.54%. Glutamate, aspartic acid and arginine, which play a major role in quality, were also oxidized, which further affected the quality of tea

(to be continued)

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