# Application of an Electronic Nose as a New Technology for Rapid Detection of Adulteration in Honey
## 4 Conclusions  
This work evaluated the capacity of an e-nose based on thin films of an ionogel composite doped with different concentrations of Fe\({}_{3}\)O\({}_{4}\) nanoparticles for discrimination between authentic and adulterated honey. The sensors were obtained by keeping fixed amounts of ionic liquid and gelatin, while suspensions with different concentrations of Fe\({}_{3}\)O\({}_{4}\) were used (0, 25, 50, and 75 mg\(\cdot\)mL\({}^{-1}\)). To evaluate the capacity of the e-nose for discrimination between authentic and adulterated honey, two strategies were considered, graphical analysis (PCA) and automated classifiers. In a preliminary analysis using data from individual cycles, PCA presented an overlapping region, while taking the average data, two clusters with no intersection were obtained. Additionally, based on data from individual cycles, the discrimination accuracy of different machine learning classifiers was calculated; IBK (k = 3) and Kstar (k = 3) presented the highest values of 97.5% and 96.6%, respectively. From the confusion matrix, sensitivity and specificity were calculated for each classifier. In the case of IBK (k = 3), sensitivity was 90.5% and specificity 94.8%, while for Kstar (k = 3), sensitivity and specificity were 95.2% and 97.4%, respectively. Taking the average data of the measures taken for each sample, the accuracy of the classifiers IBK\({}^{*}\) (k = 3) and Kstar\({}^{*}\) (k = 3) was 94.1% and 100%, respectively. In the same way, for IBK\({}^{*}\) (k = 3), the sensitivity was determined as 100% and the specificity as 90.9%. For Kstar\({}^{*}\) (k = 3), both parameters were 100%. Finally, the proposed methodology based on e-nose technology is a simple and low-cost alternative for analyzing honey frauds and can be used as a complementary tool for honey quality control, reducing the analysis time and manipulating steps. Nevertheless, further studies must be performed to optimize experimental parameters, data acquisition, and treatment steps. Additionally, more samples must be evaluated for validation of the proposed methodology for discrimination between authentic and adulterated honey. Figure 5: Confusion matrices, sensitivity, and specificity of classifiers IBK (k = 3), Kstar (k = 3), IBK\({}^{*}\) (k = 3), and Kstar\({}^{*}\) (k = 3). **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app13084881/s1](https://www.mdpi.com/article/10.3390/app13084881/s1)]([https://www.mdpi.com/article/10.3390/app13084881/s1](https://www.mdpi.com/article/10.3390/app13084881/s1)), Figure S1: PCA biplot obtained for authentic (TH, ) and adulterated honey (AH, ) based on individual cycles RRs data. Table S1: RRs data obtained by sensors during individual cycles. **Author Contributions:** Conceptualization: W.B.G., W.S.R.T., J.G. and J.G.P. ; data curation: W.B.G., W.S.R.T., E.P.C., A.N.d.C.E.S. and O.A.M. ; formal analysis: [PERSON], [PERSON] and [PERSON]; funding acquisition: [PERSON] and [PERSON]; investigation: [PERSON], [PERSON], A.N.d.C.E.S. and O.A.M. ; methodology: [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON]; project administration: [PERSON] and [PERSON]; resources: [PERSON] and [PERSON]; software: [PERSON]; supervision: [PERSON], [PERSON] and [PERSON]; validation: [PERSON], [PERSON] and [PERSON]; visualization: [PERSON] and [PERSON]; writing--original draft: [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON]; writing--review and editing: [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the Brazilian National Council for Scientific and Technological Development (CNPq) through processes 165186/2015-1, 307501/2019-1, and 424027/2018-6. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data presented in this study are available on request from the corresponding author.