Study On Novel Rapid Methods For Detection Of Food Safety Using High Sensitive Vibrational Spectroscopy

Focused on the research of new methods for detection of food safety,we effectively integrated vibrational spectroscopy and chemometrics,and went into depth on the mechanism and characteristics of vibrational spectrum of food systems.The spectral sensitivity was significantly improved in the presence of complex matrix interference,and new spectral methods for food safety detection were established.The specific research contents and results are listed as follows:(1)A single-drop Raman imaging(SDRI)strategy was proposed for simultaneous detection of multiple contaminants in milk.The coffee-ring effect was innovatively introduced into the sample preparation,and then the micro-Raman technology was combined to perform micro-region analysis.The sensitivity of Raman imaging was improved markedly.On this basis,discrete wavelet transform(DWT)was applied for the spectra processing.In this strategy,the matrix effects were greatly suppressed,and the result was exhibited in the form of imaging.The detection sensitivity for melamine,sodium thiocyanate and lincomycin were 0.1 mg·kg^-1?1mg·kg^-1 and 0.1 mg·kg^-1,meaning the high sensitivity of this method.(2)A surface enhanced Raman spectroscopy(SERS)method for the quantitative analysis of Aristolochic acid?(AA?)in Chinese herbs based on Ag nanrods array chips was developed.In this method,Ag nanrods array chips were used as SERS substrates that provide?hot spots?for Raman signals enhancing,and a portable Raman system was adopted to collect spectra.After that,the collected spectra were processed through interative DWT(IDWT)to suppress the matrix interferences.The intensity of characteristic signal was found to have a good linear relationship with the concentration of AA?in the range of 1-50?g·g^-1,with R²>98%and LOD of 0.32?g·g^-1.The RSD of results of different days was less than 1.5%,and time consumption for each sample was less than 5 minutes.(3)A digitally labeled gas-phase FTIR(DLG-FTIR)spectroscopy was proposed for rapid detection of industrial alcohol blended liquors.The liquid liquor samples were firstly transformed into gases to remove complex matrix interference in liquid samples,a G-FTIR system equipped with long-path gas cell was then applied to collect spectra of the volatiles of ten different kinds of alcoholic drinks to enhance detection sensitivity.Based on this,a digitally labeled algorithm combining IDWT,principle component analysis(PCA)and least square support vector machine(LS-SVM)was proposed to conduct data processing and classification analysis.As a result,the recognition accuracy of the LS-SVM model was higher than 97%.Measurement for each sample can be done within 3 minutes.(4)Gas-phase FTIR(G-FTIR)spectroscopy was developed for rapid discrimination of the spoilage of chicken.The volatiles of chicken were respectively measured by the G-FTIR spectroscopy that equipped with long-path gas cell.After that,a chemometrics method combining PCA with SVM was developed to analysis the G-FTIR spectra.The relationship between spoilage level and the G-FTIR of volatiles was established.The prediction accuracy of the SVM prediction model was100%.The whole process could be achieved within 3 minutus for each sample.In conclusion,the sensitivity of Raman spectroscopy and IR spectroscopy were improved effectively by combining spectral enhancing technology with chemometrics method.Our study was expected to promote the application of vibration spectroscopy in food and other complex systems,having good research and economic significance.