Identification of tea

Tea as a worldwide beverage product varieties have no less than 3000 kinds, famous tea is also countless. Such as West Lake Longjing, Dongting Biluochun, Lushan Yunwu Tea, Nanjing Yuhua Tea; Pu 'er, Tieguanyin, Narcissus Tea, Single Cluster Phoenix Tea, Kudingcha and Panda-Golden Camellia in plants, Yinghong, Dianhong and Qihong in black tea; all of them are outstanding famous teas. The quality and price of tea also vary greatly. There are a few yuan a catty of coarse tea, there are also hundreds of thousands of yuan a catty of top-quality tea. So the buying and selling department of the business community. There are very detailed grading standards and try to give reasonable prices as much as possible. But in the market economy, often appear fake famous goods or adulterated behavior. If the department of tea purchase and sale and consumer have no discernment ability, besides be cheated, still can bring huge economic loss. In particular, the business sector and its supervisory and supervisory departments need a simple, accurate and user-friendly scientific identification method. crack down on illegal acts of adulteration by speculators who pass fake products off as genuine ones and pass inferior ones off as good ones. in order to safeguard the interests of the state, producers and consumers.

There is little information on the identification of tea. The public publisher only saw an article entitled "Identification of True and False Tea" published in the magazine "Nutrition and Food Hygiene" two years ago. Two methods are described:

1)After the tea leaves are soaked in boiling water, check the number of small teeth on the edge of the tea leaves. Those with a small tooth number of 20-30 are true tea leaves, otherwise they are fake tea.

2)Cooling the brewed tea has a layer of bright taste film (more obvious after overnight) for real tea, no one is fake tea.

Although these two methods have some scientific basis, but the shortcomings are that it takes too long, and the specificity and sensitivity are not enough. For example, teabags, instant teas and canned teas are popular in today's market. They don't have complete tea leaves for you to count your teeth, and they can't wait that long to see if there's a "shiny film". From the practical point of view, people still need or call for more rapid, accurate and operable tea identification methods. The paper chromatography, colorimetry, gas chromatography, high pressure liquid chromatography and amino acid automatic analyzer can be used to determine whether the tea is real or not. For the tea industry's original effective sensory analysis, check whether tea is pure, uniform, whether there is a tea unique fragrance, intensity (color, aroma, taste, shape)......, do not have to abandon all, how much should be retained tea industry experts can discuss.

Color, aroma and taste are often different, and it is difficult to make accurate judgments. Theanine and total amino acids are determined by physical and chemical analysis method-ninhydrin determination method, which can identify whether the tea and tea are true or not. Analysis of theanine and total amino acid determination, the general use of amino acid automatic analyzer. As long as the sample is representative, after three extractions of tea, the sample will be available for ~2 hours. If there is no automatic amino acid analyzer, paper chromatography, colorimetry, gas chromatography, high pressure liquid chromatography and other methods can be used for determination.