Method for detecting crude polysaccharide in tea rich in flavones and products thereof

Abstract

A flavone-rich tea and a detection method of crude polysaccharide in products thereof, comprising the following steps: 1) taking a tea sample, and performing extraction with ethanol to obtain an extraction liquid A and a residue A; 2) centrifuging the residue A, taking a precipitate, washing with ethanol, and drying by using an oven, with a drying temperature of 60 DEG C, to obtain a crude extract; 3) performing extraction of the crude extract with water to obtain an extraction liquid B; 4) adding a macroporous resin to the extraction liquid B, and removing after adsorbing impurities; and 5) determining the content of crude polysaccharide in the extraction liquid B by using a phenol-sulfuric acid method. The present application is simple and convenient in detection, stable and accurate in result, short in detection period, and can be widely applied on a large scale.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food detection, in particular to a method for detecting crude polysaccharide in tea rich in flavonoids and products thereof. BACKGROUND

[0002] Tea leaves can be used as a beverage and contain various beneficial ingredients and have health benefits. Generally, during the production process, the content of crude polysaccharide in tea leaves needs to be detected.

[0003] At present, the main detection methods for detecting the content of crude polysaccharide in tea leaves are anthrone sulfuric acid method and phenol sulfuric acid method, especially the phenol sulfuric acid method, which is widely used due to its less environmental interference, stable and accurate detection results. However, since tea leaves usually contain flavonoids, the detection of phenol sulfuric acid method is interfered, which affects the detection accuracy of the content of crude polysaccharide in tea leaves.

[0004] Therefore, how to design a method for efficiently and accurately detecting the content of crude polysaccharide in tea leaves is a problem to be solved by those skilled in the art. SUMMARY

[0005] The present application aims at the deficiencies of the prior art, and provides a method for detecting crude polysaccharide in tea rich in flavonoids and products thereof, which is simple and convenient to detect, stable and accurate in results, short in detection period, and can be widely applied.

[0006] The technical scheme of the present application is: a method for detecting crude polysaccharide in tea rich in flavonoids and products thereof, comprising the following steps:

[0007] 1) Take tea samples, and extract with ethanol to obtain extraction liquid A and residue A;

[0008] 2) Centrifuge the residue A, take the precipitate, wash with ethanol, and dry to obtain a crude extract;

[0009] 3) Extract the crude extract with water to obtain extraction liquid B;

[0010] 4) Add macroporous resin to the extraction liquid B, and remove the impurities after adsorption;

[0011] 5) Determine the content of crude polysaccharide therein by phenol sulfuric acid method.

[0012] Further, the tea sample in step 1) is old eagle tea, the mass-volume ratio of tea sample and ethanol is 1:5-8, the extraction temperature is room temperature, and the extraction time is 8-12h.

[0013] Further, the centrifugation in step 2) is at a speed of 3500r / min for 5-15min, and the washing is performed three times, and the volume-mass ratio of ethanol to precipitate in each washing is 1:1.

[0014] Further, step 2) adopts an oven for drying, and the drying temperature is 60℃.

[0015] Further, step 3) the water is double-distilled water, the mass-volume ratio of the crude extract and the water is 1:8-10, the extraction temperature is 100℃, the extraction time is 3-5h, the extraction is repeated for three times, and the extraction liquid is combined to obtain the extraction liquid B.

[0016] Further, step 4) the adsorption time is 10-15h.

[0017] Preferably, step 1) the tea sample is a substitute tea, tea leaves or a substitute tea beverage, a tea beverage or a tea-containing tablet.

[0018] The above technical solution has the following beneficial effects:

[0019] 1. The present application uses ethanol and macroporous resin to pretreat the sample to be tested, so as to remove flavonoids, pigments and other substances in the sample, thereby avoiding the interference of the subsequent detection of the polysaccharide content. Among them, by ethanol extraction and washing of the filter residue A, most of the pigment and flavonoid interfering substances in the sample can be effectively removed to avoid the interference of flavonoids and pigments on the detection of polysaccharides. Then, the filter residue is extracted with water to extract the polysaccharides in the sample, i.e. the substance to be tested. The extraction liquid containing the substance to be tested is further treated with macroporous resin to remove the pigments and flavonoids in the sample, thereby avoiding the interference of flavonoids and pigments on the detection of polysaccharides and effectively improving the detection accuracy of crude polysaccharides.

[0020] 2. The present application limits the mass-volume ratio of the tea sample and ethanol in step 1) to 1:5-8, the extraction temperature to room temperature, and the extraction time to 8-12h, so as to remove as much as possible the pigment and flavonoid interfering substances in the sample to avoid the interference of flavonoids and pigments on the detection of polysaccharides. If the volume of the extraction liquid is too small, the pigment and flavonoid substances in the sample cannot be removed in large quantities, and if the volume of the extraction liquid is too large, it will cause waste of the extraction liquid and is not green and environmentally friendly. The filter residue A after extraction is centrifuged, washed and dried, which can effectively remove the residual interfering substances on the filter residue A and ensure the detection accuracy. In step 3), water is used to extract the crude extract, and the mass-volume ratio of the crude extract and water is controlled to be 1:8-10, the extraction temperature is 100℃, the extraction time is 3-5h, and the extraction is repeated for three times to obtain the extraction liquid B. Most of the crude polysaccharides in the crude extract are extracted, which improves the detection accuracy of the crude polysaccharide content in tea and its products, meets the detection requirements, and if the mass ratio of the crude extract and water is reduced, the temperature is too low or the extraction time is too low, the extraction efficiency of the crude polysaccharides will be reduced, and the crude polysaccharides cannot be completely extracted, which will cause the detection result to be low. If the extraction temperature is too high, part of the structure of the crude polysaccharides will change, which will also cause the detection result to be low.

[0021] Through verification by the applicant, the detection precision of the detection method of the present application on the detection of crude polysaccharide in tea samples can reach 0.998.

[0022] Further description is made in combination with the specific implementation. DETAILED DESCRIPTION

[0023] Example 1

[0024] Take 5g of old eagle tea leaves, crush, and then use 25ml of ethanol for the first extraction, the extraction temperature is room temperature (25℃), and the extraction is overnight (12h). Centrifuge the extraction liquid and the old eagle tea leaves at 3500r / min for 10min, discard the supernatant, and obtain the precipitate. Wash the precipitate with 1 times volume of ethanol (5ml) for three times in sequence. Dry the precipitate, add 15-18ml of double distilled water, and then extract in boiling water for 4h, and repeat the extraction for three times. Combine the extraction liquid (48ml), and cool to room temperature. Add 25ml of macroporous resin to the extraction liquid, and adsorb overnight (12h). Discard the macroporous resin, obtain the polysaccharide mother liquor, add water to make the volume 100ml, take 1ml of the polysaccharide mother liquor, add 1ml of phenol, shake well, add 8ml of concentrated sulfuric acid, shake well, and then react in a 100℃ water bath for 5min. After cooling, the absorbance at 495nm is 0.214.

[0025] Draw the standard curve of glucose concentration. Under the same conditions, measure the absorbance at 495nm, and draw the standard curve graph with the glucose concentration as the abscissa and the absorbance as the ordinate. The standard curve is y=0.0005x+0.0586. Substitute the above absorbance into the standard curve graph, and calculate the concentration of the crude polysaccharide in the old eagle tea leaves to be 30.69%. The content of the crude polysaccharide in the standard old eagle tea leaves is 30.74%. The results show that the detection method of the present application is an accurate and rapid detection method.

[0026] Example 2

[0027] Take 5g of green tea crude extract, crush it, and then use 25ml of ethanol to perform the first extraction, with the extraction temperature being room temperature (25℃) and the extraction time being overnight (12h). Centrifuge the extraction liquid and the green tea crude extract at 3500r / min for 10min, discard the supernatant, and obtain the precipitate. Then, wash the precipitate with 1 times the volume of ethanol (5ml) for three times in sequence. After drying the precipitate, 15-18ml of double-distilled water is added to the precipitate, and then the precipitate is extracted in boiling water for 4h, and the extraction is repeated three times. Combine the extraction liquids (45-55ml), and then cool the combined extraction liquid to room temperature. Then, add 25ml of macroporous resin to the extraction liquid, and then adsorb the extraction liquid overnight (12h). Discard the macroporous resin, and then obtain the polysaccharide mother liquor. Then, dilute the polysaccharide mother liquor to 100ml. Take 1ml of the polysaccharide mother liquor, add 1ml of phenol, shake well, and then add 8ml of concentrated sulfuric acid. Shake well, and then react in a 100℃ water bath for 5min. After cooling, the absorbance at 495nm is 0.216.

[0028] Draw a standard curve of glucose concentration. Under the same conditions, the absorbance at 495nm is measured, and then a standard curve graph is drawn with the glucose concentration as the horizontal coordinate and the absorbance as the vertical coordinate, that is, y=0.0005x+0.0586. The above absorbance is substituted into the standard curve graph, and then the concentration of the crude polysaccharide in the green tea is calculated to be 31.08%. The content of the crude polysaccharide in the standard eagle tea leaves is 31.14%. The results show that the detection method provided in the present application is an accurate and rapid detection method.

Claims

1. A method for detecting the presence of crude polysaccharides in a flavonoid-enriched tea and its products, characterized by, It comprises the following steps: 1) taking tea sample, extracting with ethanol to obtain extraction liquid A and residue A, the mass-volume ratio of tea sample and ethanol is 1:5-8, the extraction temperature is room temperature, and the extraction time is 8-12h; 2) centrifuging residue A, taking the precipitate, washing with ethanol, and drying to obtain crude extract, drying in an oven, and the drying temperature is 60℃; 3) extracting crude extract with water to obtain extraction liquid B, the water is double distilled water, the mass-volume ratio of crude extract and water is 1:8-10, the extraction temperature is 100℃, the extraction time is 3-5h, repeating extraction for three times, and combining the extraction liquids to obtain extraction liquid B; 4) adding macroporous resin to extraction liquid B, and removing after adsorbing impurities; 5) determining the content of crude polysaccharide therein by phenol-sulfuric acid method.

2. The detection method according to claim 1, characterized in that, In step 2), the centrifugal speed is 3500r / min, the centrifugal time is 5-15min, and the washing is performed for three times, and the volume-mass ratio of ethanol to precipitate in each washing is 1:

1.

3. The method of claim 1, wherein, In step 4), the adsorption time is 10-15h.

4. The method of claim 1, wherein, In step 1), the tea sample is substitute tea, tea leaf, substitute tea beverage, tea beverage or tea-containing tablet.