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Method for determining content of catechuic acid in tea and tea products

A technology for catechins and tea leaves, which is applied in the measurement of color/spectral properties, material analysis by observing the influence of chemical indicators, and analysis by chemical reaction of materials, etc., which can solve the problem of limited sources of reference substances and measurement costs High cost, high price and other problems, to achieve the effect of reduced measurement cost, high accuracy and easy procurement

Active Publication Date: 2015-04-29
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] The invention provides a method for measuring the content of catechins in tea leaves and tea products. The method uses resorcinol as a hydrochloric acid-vanillin color spectrophotometric method instead of EGCG and other catechins. Determination of the total amount of catechins in tea leaves and tea products is simple, rapid, accurate and low-cost determination to solve the existing hydrochloric acid-vanillin chromogenic spectrophotometry and HPLC methods have limited sources of reference substances, high prices and determination costs It can also provide a reference for the detection of complex compounds with chemical structures similar to catechins in natural products

Method used

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  • Method for determining content of catechuic acid in tea and tea products
  • Method for determining content of catechuic acid in tea and tea products
  • Method for determining content of catechuic acid in tea and tea products

Examples

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Embodiment 1

[0042] Example 1: The hydrochloric acid-vanillin spectrophotometric method for determining the total amount of catechins in tea leaves and tea products using resorcinol as a catechin (taking EGCG as an example) to replace the reference substance is established according to the following steps:

[0043] 1. Spectroscopic comparison of resorcinol substitute reference substance and catechin reference substance

[0044] Resorcinol is stable in nature, and it is easy to obtain high-purity products. It is easy to purchase high-purity products in the chemical reagent market and the price is relatively low. The measured UV-visible absorption curves of EGCG and resorcinol after hydrochloric acid-vanillin color development ( figure 1 ) found that in the wavelength range of 440-600nm, the condensation products of resorcinol and EGCG with vanillin have similar spectral properties and high color sensitivity. In the subsequent determination of the standard curve, it was found that the abso...

Embodiment 2

[0074] Embodiment 2: This embodiment optimizes the hydrochloric acid-vanillin color reaction system in the method provided by the present invention, and the specific steps are as follows:

[0075] (1) Preparation of alternative reference substance and standard solution of reference substance

[0076] Take 10 mg of high-purity resorcinol (purity ≥ 99.5%, HPLC grade) and EGCG (standard product) and dissolve them in 50 mL of distilled water to prepare 200 mg / L replacement reference substance and standard solution stock solution of reference substance . In the determination, pipette a certain amount of standard solution stock solution and dilute to a constant volume to make a gradient concentration solution for the standard curve and f The determination of the value and the optimization of the color reaction system.

[0077] (2) Preparation of color developer

[0078] Dissolve vanillin (analytical pure) in methanol to prepare 4% (mass percentage concentration), and mix with...

Embodiment 3

[0085] Example 3: This example compares the method provided by the present invention with other methods for determining the content of catechins in tea extract (tea polyphenol I). The specific steps are as follows:

[0086] (1) the method that the present invention establishes

[0087] Accurately weigh 20 mg, 30 mg, 40 mg, 50 mg, and 60 mg of samples of tea extract powder (tea polyphenol I) respectively, add 50 mL of water, dissolve with ultrasonic assistance and dilute to 100 mL with water, pipette 1 mL, and follow the steps in 2.2 ( 1) Measure the absorbance by the method in A (See attached for UV-vis absorption curve Figure 7 Curve 1), with resorcinol standard curve data, with formula (2) ( f Take 0.82) to obtain the average catechin content of 460.0mg / g, RSD=1.6%.

[0088] (2) EGCG is the hydrochloric acid-vanillin method of reference substance

[0089] Accurately weigh 20mg, 30mg, 40mg, 50mg, 60mg of tea extract powder (tea polyphenol I) samples respectively, add 50...

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Abstract

The invention discloses a method for determining the content of catechuic acid in tea and tea products. The method comprises the following steps: preparing a gradient standard solution by adopting resorcinol instead of catechuic acid reference substance, preparing a to-be-tested solution from tea or tea products, determining the absorbance of the gradient standard solution through a hydrochloric acid-vanillin developing system under the wavelength of 510nm, establishing a standard curve taking molarity as an x-coordinate and establishing a regression equation and then determining the absorbance of the to-be-tested solution, resolving the unit concentration of resorcinol in the to-be-tested solution from the regression equation, then calculating the content of catechuic acid in tea and tea products according to the dilution factor, resorcinol unit number contained in the unit relative molecular mass of the catechuic acid reference substance, and correction factor. The resorcinol used is stable in property, easily available and low in price, the problems that the resorcinol reference substance is limited in sources, expensive in price and high in determination cost can be solved, and the method is simple to operate, accurate in results and good in repeatability.

Description

technical field [0001] The invention relates to a method for determining the content of catechin in tea leaves and tea products. Background technique [0002] Catechin compounds in tea are a class of functional active ingredients that are relatively abundant in tea. They have a wide range of health care and pharmacological effects and strong food antioxidant properties. and one of the hotspots in the field of food research. [0003] Modern science has proved that catechin is a group of plant polyphenols with a cycloalkan-3-ol structure, and its total amount accounts for about 65-80% of tea polyphenols, mainly including catechin (C), epicatechin Catechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (CG), epicatechin gallate (ECG), gallocatechin gallate (GCG), epigallocatechin gallate (EGCG), etc. [Irena Vovk, et al, Separation of eight selected flavan-3-ols on cellulose thin-layer chromatographic plates (J). Journal of Chromatography A, 2005, 1077(6...

Claims

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Application Information

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IPC IPC(8): G01N21/78G01N21/31
Inventor 唐辉张晓春
Owner KUNMING UNIV OF SCI & TECH
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