Rapid Detection of Escherchia coli and Salmonella Typhimurium Using Lab-Made Electronic Nose Coupled with Chemometric Tools

Abstract

This study aims to investigate the performance of a lab-made electronic nose coupled with chemometric tools for detecting <em>Escherichia coli</em> (<em>E. coli)</em> and <em>Salmonella Typhimurium</em> (<em>S. Typhimurium</em>) inoculated in media. The pathogenic <em>E. coli</em> and <em>S. Typhimurium</em> play a significant role as the agent causing food-borne diseases, posing a threat to human health worldwide. Some advanced analytical instruments like RT-PCR and GC-MS are often used for detecting such pathogenic bacteria. Unfortunately, they are not suitable for rapid and routine measurements because of time-consuming, require experts, and complicated sample preparation. Otherwise, electronic nose (e-nose) has been reported to be successful for profiling volatile compounds released by various biological materials. The e-nose comprised eight types of metal oxide gas sensors connected with a data acquisition system and chemometric tools. For this purpose, Fast Fourier Transform (FFT) was applied for signal pre-processing and feature extraction to all datasets collected by the sensor array in the e-nose. Furthermore, chemometric tools are used for classification models of all extracted features, including linear and quadratic discriminant analysis (LDA and QDA) and support vector machine (SVM). As a result, SVM showed the highest performance, enabling identifying <em>E. coli</em> and <em>S. Typhimurium</em> inoculated TSB with an accuracy of 99% and 98%, respectively. Among the chemometric tools, the e-nose-SVM also resulted in the highest accuracy in differentiating <em>E. coli</em> from <em>S. Typhimurium</em> of 84%. These results motivated e-nose to have a high prospect to rapidly detect such bacteria for food safety and quality control inspection, particularly potential quarantine products.