Study On The Quantitative Detection Method Of Glutamate In Beef Based On Biosensor

As a rich nutrients and delicious food,beef products'amino acid composition is close to the human body.In this paper,glutamate biosensor was studied and prepared for the determination of glutamate in beef,which is the typical umami amino acids.The conditions of preparing glutamate biosensors were investigated and applied to the detection of the rib eye beef of the Working black cattle and Yanbian cattle.The detection results of biosensor were compared with the amino acid analyzer to verify the practicability of glutamate biosensors.Meanwhile,the content of glutamate in beef samples of different varieties was also studied and analyzed.The main research contents and results are as follows:?1?Prepared the oxidized graphene?GO?and the structure was characterized by Fourier transform infrared spectroscopy?FTIR?and X-ray diffraction.The prepared graphene oxide was mixed with chloroauric acid?HAuCl₄?,chitosan?CS?and acetic acid?HAc?to prepare Au NPs-GO-CS-HAc suspension and modified gold electrode surface.The modified electrode and bare gold electrode were characterized by scanning electron microscopy?SEM?.Using cyclic voltammetry?CV?to study the dosage of modifier,when the dosage was 10?L,the response current was maximum.bare gold electrode,Au NPs-GO-CS-HAc modified Au electrode,GO-CS-HAc modified Au electrode,Au NPs-CS-HAc modified Au electrode immersed in 5 mmol/L[Fe?CN?₆]^3-/[Fe?CN?₆]^4-containing 0.3 mol/L KCl mixed solution were characterized by cyclic voltammetry?CV?and differential pulse voltammetry?DPV?.The experimental results show that the CV and DPV have the same trend of response current to different modified electrodes,indicating the accuracy of the modified electrode.4 CV curves of the Au NPs-GO-CS-HAc modified electrode were obtained in the electrolyte solution.The standard deviation of redox peak current intensity is within 5%,show that Au NPs-GO-CS-HAc modified electrode was highly reproducible.?2?Immobilization of glutamate oxidase?GluOx?onto Au NPs-GO-CS-HAc modified Au electrode.dosage and concentration of GluOx,optimum pH and temperature conditions were studied,the optimum current was obtained at pH 7.5,the optimum temperature of biosensor was 30?.Different scanning speed of Au NPs-GO-CS-HAc-L-GluOx modified Au electrode were studied by CV,there was a good linear relationship between the redox peak current and the square root of scan rate,linear equation respectively:I_pa??A?=7.58+3.9V^1/2?mV/s?,R²=0.996,I_pc??A?=-6.5-3.79V^1/2?mV/s?,R²=0.996.The Au electrodes of three modified phases were characterized by CV and DPV,the results showed that the modifier and glutamate oxidase were successfully modified to the surface of bare gold electrode.Under the optimum conditions,the glutamate biosensor showed a linear current response to the substrate concentration in the range from 0.2×10^-33 to 1.4×10^-33 mol/L with a detection limit of 0.23×10^-44 mol/L in glutamate detection.Additionally,the Glutamate detection exhibited high selectivity,good repeatability and stability.?3?The glutamate biosensor was used for the detection of actual samples,and the accuracy of glutamate biosensor was verified by using amino acid analyzer.The results detected by glutamate biosensor is similar with amino acid analyzer,with high accuracy and fast detection speed and simple operation.In addition,the results show that the content of glutamate in the rib eye beef of the Working black cattle is higher than that of the Yanbian cattle,and for the same parts of cooked beef and raw beef,the content of glutamate in the cooked beef is higher than the raw beef.