Method for detecting and evaluating soup color of jasmine tea

Abstract

The invention relates to the technical field of tea drinks, in particular to a method for detecting and evaluating the soup color of jasmine tea. The color difference values a *, b * and L * of the jasmine tea soup are measured by a colorimeter according to a specific detection method, then the hue M = a * / b * is calculated, the quality of the tea soup is judged by calculating the score value of the tea soup according to the linear relation among L *, M and the color score of the jasmine tea soup, and the method is objective, accurate and standard.

Description

Technical Field

[0001] The present invention relates to the technical field of tea beverages, and particularly to a method for detecting and evaluating the color of jasmine tea soup. Background Art

[0002] The sensory quality of tea is a comprehensive reflection of quality factors such as the color, aroma, taste, and shape of the tea. The soup color is one of the important indicators for evaluating the quality of tea. High-quality jasmine tea should have a tender yellow, light yellow, or yellow soup color, which is clear and bright. At present, the evaluation methods for the color quality of tea soup mainly include sensory evaluation and color difference analysis.

[0003] Sensory evaluation is that an expert evaluation group gives descriptive comments and scores to the samples according to certain evaluation criteria and rich experience. In actual production and most research, it is based on sensory evaluation, which has the advantages of being fast and intuitive. However, sensory evaluation is restricted by environmental factors and more affected by the evaluation conditions and experience of the evaluators, with strong subjectivity. There are certain deviations in the judgment results of different evaluators; in addition, the descriptive terms of sensory evaluation are usually relatively vague, lacking an objective quantitative evaluation standard. Therefore, sensory evaluation cannot fully achieve standardization and objectivity.

[0004] A color difference meter is a more objective and scientific color measurement instrument. At present, the modern instrumental analysis used for color evaluation is mainly color difference analysis. Color difference analysis has more applications in black tea processing and product quality evaluation, such as evaluating the brightness of black tea soup color and monitoring black tea fermentation, but it is less applied to the evaluation of the color of jasmine tea. Summary of the Invention

[0005] In order to solve the above technical problems existing in the prior art, the present invention provides a method for detecting and evaluating the color of jasmine tea soup, specifically as follows:

[0006] A method for detecting and evaluating the color of jasmine tea soup uses a color difference meter to measure the color difference value of jasmine tea soup and calculates the hue M value, and further determines the color of jasmine tea soup through the hue M and L*;

[0007] The specific steps are as follows:

[0008] Pour 120 mL of tea soup into a glass colorimetric dish with a length, width, and height of 5 cm × 5 cm × 5 cm, place the colorimetric dish in the center of the photographing box, turn on the LED light board, use a color difference meter to select 4 points at the center and on the diagonal of the colorimetric dish to measure the color difference a*, b*, and L* values of the tea soup, calculate the average value of the color difference a*, b*, and L* of the 5 points as the color difference value of the tea soup, and calculate the hue M value according to the formula M = a* / b*;

[0009] Judgment of the quality of jasmine tea soup color: According to the formula Y = 1.093 X1 +3.438 X2Calculate the tea soup score value Y, judge the quality of the tea soup according to the range of Y, and judge the color of the jasmine tea soup.

[0010] Furthermore, the b* value of the tea soup color difference is specifically the average value of the b* values of the tea soup color difference measured at 4 points on the center and diagonal lines of the colorimetric cell.

[0011] Furthermore, the a* value of the tea soup color difference is specifically the average value of the a* values of the tea soup color difference measured at 4 points on the center and diagonal lines of the colorimetric cell.

[0012] Furthermore, the L* value of the tea soup color difference is specifically the average value of the L* values of the tea soup color difference measured at 4 points on the center and diagonal lines of the colorimetric cell.

[0013] Furthermore, the jasmine tea soup is obtained by brewing jasmine tea at a tea-to-water ratio of 1:50, filtering out the tea soup after boiling water brewing for 5 minutes.

[0014] Furthermore, the jasmine tea is at a tea-to-water ratio of 1:50, and this ratio is the ratio of the mass of tea leaves (g) to the volume of brewing water (mL).

[0015] Furthermore, the characteristics of the photographing box are: the length, width, and height are 60 cm × 60 cm × 60 cm, the upper, lower, left, right, and back are pure white background boards, the front is open, and a ring-shaped LED light board with a diameter of 15 cm is installed at the center of the top, and the width of the light board is 1 cm.

[0016] Furthermore, the characteristics of the photographing method are: photographing in natural light mode.

[0017] Furthermore, Y is the tea soup score value. According to GB / T 23776-2018 "Tea Sensory Evaluation Method" and GB / T 22292-2017 "Jasmine Tea", the basis for judging the tea soup quality is as follows:

[0018] Color of tea infusion Scoring range Grade Dark yellow or yellowish green, lacking brightness 70～79 Grade Three Yellow and bright or yellowish green and bright 80～89 Grade Two Tender yellow and bright 90～100 Grade One

[0019] Furthermore, X1 is the L* value.

[0020] Furthermore, X2 is the M value.

[0021] Compared with the prior art, the technical effects of the present invention are reflected in:

[0022] The present invention uses a color difference meter to measure the color difference values a*, b*, and L* of the jasmine tea soup according to a specific detection method, then calculates the hue M = a* / b*, and according to the linear relationship between L*, M and the jasmine tea soup color score, judges the tea soup quality by calculating the tea soup score value. This method is objective, accurate, and standard. Specific embodiments

[0023] The technical solution of the present invention will be further limited in combination with specific embodiments, but the scope of protection required is not limited to the description made.

[0024] Example: Pick out the flower-like inclusions such as petals, calyces, and flower stalks in the tea sample. Weigh 3.0 g of the tea sample and put it into a 150 mL white porcelain evaluation cup, fill it with boiling water, cover it and soak for 5 minutes, then filter out the tea soup into a white porcelain evaluation bowl. The evaluation cup and bowl meet the requirements and specifications of GB / T 23776-2018. Professional personnel with a senior tea-tasting qualification certificate observe the color of the tea soup, score according to the scoring standard of GB / T 23776-2018 and record the comments. Pour 120 mL of the tea soup into a colorimetric cell, put the colorimetric cell into a photo box, and measure the color difference value of the tea soup with a color difference meter according to the above method.

[0025] Table 1 Color difference value and sensory evaluation of jasmine tea soup

[0026]

[0027]

[0028] Regression linear analysis of color difference value and score:

[0029] Input / removed variables

[0030] Mold Transport Transfer 1 <![CDATA[X2, X1 a > . Transport

[0031] a. All requested variables have been entered.

[0032] Model Summary

[0033]

[0034] a. Predictors: (Constant), X2, X1.

[0035] Anova b

[0036]

[0037] a. Predictors: (Constant), X2, X1.

[0038] b. Dependent Variable: Y

[0039] Coefficients a

[0040]

[0041] a. Dependent Variable: Y

[0042] R 2 = 0.831 > 0.5 (R2 The closer it is to 1, the better the model is. 2 >0.5 is significant), P<0.05, the linear regression equation has a good fit and is statistically significant. The linear regression equation is:

[0043] Y=1.093X1+3.438X2+62.265

[0044] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A method for detecting and evaluating the color of jasmine tea soup, characterized in that, Use a color difference meter to measure the color difference value of the jasmine tea soup, calculate the hue M value, and further determine the color of the jasmine tea soup through L* and M; The specific steps are as follows: Pour 120 mL of the tea soup into a glass colorimetric dish with a length, width, and height of 5 cm × 5 cm × 5 cm. Place the colorimetric dish in the center of the photo box. Turn on the LED light board. Use the color difference meter to measure the color difference a*, b*, and L* values at the center and 4 points on the diagonal of the colorimetric dish. Calculate the average value of the color difference a*, b*, and L* of the 5 points as the color difference value of the tea soup, and calculate the hue M value according to the formula M = a* / b*; Quality determination of the color of jasmine tea soup: According to the formula Y = 1.093 X1 + 3.438 X2 + 62.265 to calculate the soup score value Y, and judge the quality of the tea soup according to the range of Y to judge the color of jasmine tea soup.

2. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, characterized in that The b* value of the tea soup color difference represents the change in color between blue (-b*) and yellow (+b*).

3. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, characterized in that, The a* value of the tea soup color difference represents the change in color between green (-a*) and red (+a*).

4. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, characterized in that, The L* value of the tea soup color difference is the lightness, representing the change in color between dark (L* = 0) and bright (L* = 100).

5. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, characterized in that, The jasmine tea soup is obtained by brewing jasmine tea at a tea-to-water ratio of 1:50, boiling it with boiling water for 5 minutes, and then filtering out the tea soup.

6. The method for detecting and evaluating the color of jasmine tea soup according to claim 5, characterized in that, The jasmine tea is at a tea-to-water ratio of 1:50, and this ratio is the ratio of mass (g) to volume (mL).

7. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, wherein The characteristics of the photo box are: length, width, and height are 60 cm × 60 cm × 60 cm, the upper, lower, left, right, and back are pure white background boards, the front is open, and a circular LED light board with a diameter of 15 cm is installed at the center of the top, and the width of the light board is 1 cm.

8. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, characterized in that, When taking pictures, select the natural light mode for the photo box.

9. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, wherein The Y is the tea soup score value. According to GB / T 23776-2018 "Methods for Sensory Evaluation of Tea" and GB / T 22292-2017 "Jasmine Tea", the basis for judging the tea soup quality is as follows:

10. The method for detecting and evaluating the color of jasmine tea soup according to claim 1, characterized in that, The X1 is the L value, and the X2 is the M value.

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