Construction Of Colorimetric Array Sensor Based On Anode Aluminum Oxide Film And Its Application In Fish Freshness Detection

Fish meat is susceptible to spoilage and deterioration during storage.Therefore,it is of great significance to accurately judge the freshness of fish meat.In this thesis,a colorimetric array sensor that can be applied to fish freshness detection is constructed on the basis of anodized aluminum and 13 p H dyes as sensing reagents.In terms of sensor construction,the effects of different oxidation voltage,temperature,electrolyte concentration and oxidation time on sensor responsiveness were studied.The results show that the optimal conditions for the sensor substrate are voltage 15 V,temperature 20°C,sulfuric acid electrolyte concentration 180 g/L,and oxidation time 45 min.The microstructure and property of the colorimetric sensing array were characterized and analyzed.The results showed that the surface of the anodized aluminum substrate was a porous structure,which helped to fix various sensing dyes.The anodized film is mainly composed of amorphous Al₂O₃.Water contact angle characterization analysis results show that the prepared sensing array has hydrophilic properties.The colorimetric sensor array constructed in the study was applied to the detection of freshness of turbot under different storage times,and the R,G,and B values of the array points before and after the reaction were processed to obtain the response difference spectrum.The research results show that the difference spectrum can successfully distinguish the turbot with different freshness grades.Cluster analysis（HCA）and principal component analysis（PCA）were carried out according to the characteristic matrix composed of the response values of the difference spectrum,combined with the analysis results of volatile base nitrogen content at different storage times,the results showed that the storage time was 0-10 h for TVB-N content between 6.55 and 13.80 mg/100 g is a superior product,TVB-N content between 12-20 h is between 15.23-28.33 mg/100 g as a qualified product,and TVB-N content is above 32.85 mg/100 when exceeding 22 h,it is corrupt after 22 h.Finally,the colorimetric sensor array constructed in this study was applied to the detection of Sciaenops ocellatus and carp samples.The difference between the predicted value displayed by the output spectrum and the actual TVB-N value was not significantly different.The feature matrix was analyzed by HCA,and the results were consistent with the results of the difference spectrum analysis.The above results indicate that it is feasible to apply the sensor array studied in this paper to the discrimination of freshness of other fish.