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Method for judging freshness of green tea based on Raman spectrum

A Raman spectroscopy, green tea technology, applied in Raman scattering, material analysis by optical means, material excitation analysis, etc., can solve the problems of long detection time, complicated processing process, etc., achieve good peak separation, Raman The effect of strong signal and shortened detection time

Pending Publication Date: 2021-06-29
ANHUI AGRICULTURAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is that the pretreatment process of the green tea quality identification method in the prior art is complicated, the detection time is long, and some compounds in the tea leaves will also change during the treatment process. Methods

Method used

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  • Method for judging freshness of green tea based on Raman spectrum
  • Method for judging freshness of green tea based on Raman spectrum
  • Method for judging freshness of green tea based on Raman spectrum

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] The method for judging the freshness of green tea based on Raman spectrum comprises the following steps:

[0058] (1) Preparation of tea soup: Weigh 1 g of dry tea and place it in a conical flask, add 50 mL of boiling water, cover it and place it in a water bath at 70°C for 30 minutes, take it out, cool it to room temperature, and filter the tea soup for detection.

[0059] (2) Preparation of nano-silver glue: dissolve 0.036g silver nitrate in 20ml ultrapure water to make silver nitrate mother liquor, dissolve 0.1g sodium citrate in 10ml ultrapure water to make sodium citrate mother liquor, then take 2mL nitric acid Dissolve the silver solution in 49mL of ultra-pure water, boil it in a microwave oven on high heat until it boils, take it out quickly, add 1mL of sodium citrate mother liquor, then put it in the microwave oven and continue to cook on high heat until the color of the solution turns gray-green, take it out and cool it down to room temperature, and set aside a...

Embodiment 2

[0071] The difference between this embodiment and embodiment 1 is that the ratio of dry tea to boiling water is adjusted, as shown in Table 1.

[0072] serial number Amount of tea (g) Water injection volume (ml) Water bath temperature (℃) Water bath time (min) 1 1 50 100 10 2 3 50 100 10 3 1 50 100 30 4 1 50 70 30 5 3 50 70 30 6 1 (tea powder) 50 70 30 7 1 50 70 60

[0073] The Raman signal is related to the concentration of substances in the tea soup to a certain extent, so increasing the concentration of the tea soup will effectively enhance the signal of the tea soup. In order to screen out a better tea-to-water ratio, 7 control experiments were set up, and the results are as follows: Figure 5 As shown, the spectrum of No. 4 treatment group corresponds to the black spectrum at the top of the figure. When the tea water ratio is 3:50 and the Raman signal of the tea soup is the strongest and the pe...

Embodiment 3

[0075] The samples of fried green tea in 1998 and the sample of fried green tea in 2018 were used for Raman detection. The tea samples were all from the evaluation room of Anhui Agricultural University and stored at room temperature. Weigh 1g of dry tea and place it in a conical flask, add 50mL of boiling water, cover it and place it in a water bath at 70°C, incubate for 30min, take it out and cool it to room temperature, then filter the tea soup for detection.

[0076] Take an appropriate amount of tea soup and mix it with the same amount of silver colloid solution prepared in Example 1. After mixing evenly, drop it on a gold-plated glass slide. After air-drying, perform Raman detection. Raman detection parameters are set to excitation wavelength 785nm, power 25mW, 10x objective lens , the grating is 600 reticles, and the acquisition range is 300-1800cm -1 , the number of acquisitions is 3 times, and the total acquisition time is 6s. The Raman test results were as Figure 6...

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Abstract

The invention discloses a method for discriminating the freshness of green tea based on Raman spectroscopy and relates to the field of tea quality discriminating. The method comprises the following steps of 1, the boiling water being added into the green tea, and the green tea being covered and placed in a water bath kettle at the temperature of 70-100 DEG C for water bath; the ratio of the mass of the green tea to the volume of the boiling water being (1-3): (50-100); (2) preparing nano-silver colloid; (3) mixing the tea soup with nano-silver colloid in an equal amount, dripping the mixture on a glass slide, air-drying the mixture, and performing Raman detection in a collection range of 300-1800cm<-1>; and (4) carrying out baseline removal and smoothing pretreatment on the Raman spectrum, then carrying out OPLS-DA analysis on data, and carrying out discrimination according to spectral difference. Compared with the prior art, the method is advantaged in that the tea soup is simply brewed and used for Raman detection, then freshness of the green tea is judged, the sample pretreatment method is simple, the most original style of the tea soup is reserved, and the method can be widely applied to the fields of tea quality identification and the like.

Description

technical field [0001] The invention relates to the field of tea quality identification, in particular to a method for judging the freshness of green tea based on Raman spectrum. Background technique [0002] Green tea is one of the main teas exported by China, and its storage and preservation problems are particularly prominent, and problems such as the quality determination and shelf life of green tea still need to be resolved urgently. At present, the vast majority of experts and scholars at home and abroad believe that the aging deterioration of green tea includes autooxidative deterioration and enzymatic oxidation deterioration. Studies have found that green tea stored for one year will have significant changes in various quality factors, and the color and taste of tea soup will change significantly. Also changes. But what is the quality standard of aging and deterioration? It is difficult for different people to get consistent evaluation results; even the same person ...

Claims

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Application Information

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IPC IPC(8): G01N21/65
CPCG01N21/65G01N21/658G01N2021/655
Inventor 戴前颖肖梦暄肖明霁王辉强郑芳玲安琪
Owner ANHUI AGRICULTURAL UNIVERSITY
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