Determination of Amylose on Pueraria Powder
Pueraria has a variety of health functions such as lowering blood pressure, and it is a dual-use plant for medicinal and food use. The main components of Pueraria lobata are Pueraria starch, Pueraria lobata and Pueraria flavonoids. Pueraria starch is rich in many essential amino acids and trace elements such as selenium, tellurium, zinc, manganese, etc. It has pharmacological effects such as improving heart and brain blood circulation. In addition, Pueraria starch also has a series of functions different from other starches. Properties, such as starch paste transparent, high viscosity, gel in the frozen condition is not easy to syneresis, indicating that Pueraria starch has its unique characteristics in the molecular structure. For the determination of amylose can make a good judgment on the relevant parameters of Pueraria powder.
Amylose and amylopectin were used to determine the choice of dual wavelengths. 1 mL of standard solution was taken and placed in a 50 mL volumetric flask. Distilled water was added to 30 mL. The pH was adjusted to about pH 3.5 with 0.1 mol/L HCl solution, and 0.5 mL of iodine reagent was added. Distilled water to volume. Let stand for 20 min, use distilled water as a blank, and scan in the wavelength band of 400-800 nm to obtain an absorption spectrum. As a method for the determination of amylose and amylopectin, two wavelengths were selected. The amylose regression equation was established, and 0.3, 0.5, 0.7, 0.9, 1.1, and 1.3 mL amylose standard solutions were respectively taken in a 50 mL volumetric flask, distilled water was added to 30 mL, and the pH was adjusted to about pH 3.5 with 0.1 mol/L HCl solution. Add 0.5 mL iodine reagent and make up to volume with distilled water. Let stand for 20min, use distilled water as blank, measure the absorbance value A in the measurement of dual wavelengths, use the absorbance difference ΔA as the independent variable, and use the corresponding amylose content as the variable, establish the linear regression equation of amylose.
The determination wavelength of amylose was 617nm and 476nm, and the determination wavelength of amylopectin was 415nm and 532nm. The regression equations of amylose and amylopectin were established and the content of amylose in Pueraria starch was obtained. 18.29%, the content of amylopectin was 77.24%. Double-wavelength spectrophotometry was used to subtract out the interaction between the two starch absorption backgrounds. The comparison of relative standard deviations showed that the use of dual-wavelength method to determine the content of straight and amylopectin in Pueraria lobata starch has the advantage of high precision. Pueraria can be used when the two starch content.
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