Evaluation Of Meat Eating Quality Based On Carbon-based Nanomaterials

Meat quality includes meat color,tenderness,umami and juiciness.With the improvement of living standards,the demand for various types of meat is constantly increasing,and people's requirements for the quality of meat are getting higher and higher.Therefore,rapid detection and evaluation of the edible quality of meat is a hot topic in the field of meat science.In fully bleeding muscles,myoglobin mainly exists as oxygenated myoglobin?Oxy Mb?and methemoglobin?Met Mb?.The difference between the two is the valence of iron ions in the center of the porphyrin ring.In meat storage and processing,Mb content and morphology are the most direct factors affecting meat color.Therefore,the establishment of quantitative detection methods for Fe²⁺and Fe³⁺is the key to the evaluation of different forms of myoglobin.Several analytical methods have been developed and applied for the differential detection of Fe²⁺and Fe³⁺,including inductively coupled plasma mass spectrometry?ICP-MS?,atomic absorption spectrometry?AAS?,capillary electrophoresis,and fluorescence spectroscopy.However,these instruments require lengthy sample preparation procedures and complex instruments,and are not suitable for online or on-site analysis.The main umami substances in meat are umami amino acids?glutamic acid,aspartic acid,etc.?and nucleotides?5'-guanylic acid,5'-inosinic acid,etc.?.At present,the common method for evaluating umami is the electronic tongue.Due to its selectivity and limitation,the electronic tongue has a specific application range and cannot be quantitatively analyzed.A common detection method for nucleotides is high-performance liquid chromatography,which has high detection costs,complicated sample pretreatment processes,and requires specialized test personnel and consumes a lot of time.Therefore,there is an urgent need to find an efficient,convenient and highly sensitive method for detecting the edible quality of meat.Based on this,the specific research contents of this article are as follows:1.Manganese dioxide-graphene nanorods?MnO₂-GNRs?were synthesized by hydrothermal method.The materials were characterized by scanning electron microscope?SEM?,X-ray diffraction spectrometer?XRD?,Fourier transform infrared spectroscopy?FT-IR?and other instruments.The results showed that MnO₂ and graphene had rod-shaped and layered structures,respectively,and they were well combined.The MnO₂-GNRs were modified on the surface of glassy carbon electrode?GCE?by the drop coating method to construct an electrochemical sensor.After the conditions were optimized,the differential pulse voltammetry?DPV?was used to detect iron ions in a Tris-HCl buffer solution at pH=5.5.The linear concentration ranges of Fe²⁺and Fe³⁺were 0.005 mol/L?1 mol/L and 5×10^-4 mol/L?1 mol/L,respectively.The degree of oxidation of meat can be indirectly judged by detecting the concentration of iron ions.Therefore,the sensor developed a fast and sensitive method for quantitatively determining the quality of meat.2.Nitrogen-doped graphene quantum dots?N-GQDs?were synthesized by hydrothermal method.Transmission electron microscopy?TEM?,X-ray photoelectron spectroscopy?XPS?,Fourier transform infrared spectroscopy?FT-IR?and other analytical instruments were used to characterize the morphology and element bonding structure of the synthesized material.The results showed that the material had a lamellar structure of doped graphene material and lattice defects caused by doping,and the surface of the material was rich in hydroxyl and carboxyl groups,which reasonably explained the material's good solubility and dispersibility.The steady-state and transient fluorescence spectrometers were used to characterize the optical properties of materials such as quantum yield.The quantum yield of N-GQDs reached 38%.The material was highly fluorescent and relatively stable,so it was used to construct fluorescent probes to specifically detect the main umami amino acids in meat.Through the study and optimization of experimental conditions,the concentration of glutamic acid?Glu?and aspartic acid?Asp?in the range of 1?400?g/m L can establish a good linear relationship with the fluorescence quenching signal.Compared with the amino acid analyser,the fluorescence sensor had the advantages of simplicity and fast detection speed.3.Based on bulk graphite-like carbon nitride?g-C₃N₄?,graphite-like carbon nitride quantum dots?g-C₃N₄QDs?were successfully prepared by hydrothermal method.Characterization results of TEM,FT-IR and other instruments showed that the bulk g-C₃N₄ was successfully peeled into g-C₃N₄QDs by hydrothermal method and the particle size was around 10 nm.Ultraviolet-visible spectrometer?UV-vis?and molecular fluorescence spectrometer characterization of the quantum dots showed that g-C₃N₄QDs has good light absorption and fluorescence properties,and was used to construct fluorescent probes.IMP quenched the fluorescent signal of the probe.This method had the advantages of simplicity,fastness,high sensitivity,etc.