Litchi polyphenol sample preparation: Weigh 10g of litchi skin and litchi core for crushing, add distilled water to the crushed material according to the material-liquid ratio of 1:8g/ml, boil for 0.5h, soak in 70°C water for 4h, filter and separate to obtain The first filtrate and the first residue, and finally dry the residue, add 50% acetone to the residue according to the solid-liquid ratio of 1:6g/ml, soak at 60°C for 8h, and then filter and separate to obtain the second filtrate and the second Residue, soak the secondary residue in hot water, filter and collect the third filtrate, combine the primary filtrate, the second filtrate and the third filtrate and dry it to obtain the crude extract, transfer the crude extract to a 25ml volumetric flask, add distilled water Dilute to the mark to prepare litchi polyphenol samples.
Detection of polyphenols in lychee:
Accurately measure 2.0, 4.0, 6.0, 8.0, 1.0, 1.2, 1.4 ml of gallic acid reference solution with a concentration of 0.004 mg/ml, put them in 10 ml brown measuring bottles, and then add 0.5 ml of 0.1 mol/L FeCl3 solution, 0.5ml of K3Fe(CN)6 solution with a concentration of 0.0008 mol/L, and 0.5ml of HCl solution with a concentration of 0.1000 mol/L were all dilute to 10 mL and shaken well, and left for more than 10 minutes. Blank, measure the absorbance value at a wavelength of 670nm, draw the standard curve with the concentration of gallic acid reference substance solution as the abscissa, and the absorbance value as the ordinate, and the regression equation is y=0.009x+0.1563, r=0.9923.
Sample detection: Take 3ml of lychee polyphenol sample and add it to a 10ml volumetric flask, then add 0.5ml FeCl3 solution with a concentration of 0.1 mol/L, 0.5ml K3Fe(CN)6 solution with a concentration of 0.0008 mol/L, and 0.5ml concentration Make a 0.1000 mol/L HCl solution and set the volume to 10 ml, place it for more than 10 min to measure the absorbance value at a wavelength of 670nm, and calculate the content based on the standard curve.
In a preferred embodiment, before measuring the absorbance value, the gallic acid reference substance solution needs to be placed for 15min after adding FeCl3, K3Fe(CN)6 and HCl solution to constant volume, and then measure the absorbance value; the litchi polyphenol sample is After adding FeCl3, K3Fe(CN)6 and HCl solution to constant volume, it needs to stand for 15min, and then measure the absorbance value.
The utilization of polyphenols in litchi, the development of a new plant polyphenol resource, and the application research in the fields of cosmetics, food, medicine, etc., will have a positive effect on the comprehensive utilization of litchi resources in my country and the development of post-harvest deep processing technology of litchi. significance. Usually people will throw away the shell and core after eating litchi. This paper uses litchi waste (shell and core) as raw material to extract the polyphenols, and then determine the content of litchi polyphenols by targeted detection methods. The components in litchi were quantitatively analyzed, and the data of polyphenols in litchi were collected, which is beneficial to the subsequent comprehensive development of litchi.
