## 3 Results
### Validated Regression Models of Commercial Poppy Seed Oil Samples
Advances in electronics, photonics, and chemometrics have resulted in small, portable, and even handheld spectrometers that are capable of reliable on-site food product analysis. These developments present the possibility of rapid detection of critical parameters throughout the entire food supply chain without any complicated sampling protocols. Ongoing research is directed at further miniaturization, although challenges persist in the redesign of optical components and sourcing cost-effective materials. Technologies like micro-electro-mechanical (MEMS) and/or linear variable filter devices are promising development of energy-efficient, low-cost, robust, and highly mobile spectrometers combined with efficient light sources and low-cost photodetectors that can be applied in-line and on-line applications [54; 55; 56]. Compared to conventional techniques like GC-FID detection, FT-IR spectroscopy offered numerous advantages, including being rapid, non-destructive, and relatively inexpensive. Although highly accurate in the analysis of fatty acid composition, GC-FID requires considerable preparation of the sample and is rather time-consuming; hence, it is less suitable for routine use in quality control. On the contrary, the portable FT-IR sensor used in this study enabled the direct testing of oil samples without any special preparation, significantly simplifying the authentication process. Finally, the developed chemometric models correctly identified all the adulterated samples using SIMCA classification algorithms and proved the robustness of the method. In addition, the PLSR models showed very good predictive performance of the predominant fatty acid composition, achieving high external validation coefficients and a low prediction error. These results point out the possibility of the method providing reliable, real-time predictions of fatty acid profiles, therefore presenting an efficient alternative to the traditional GC-FID methods. The portability of the FT-IR sensor makes it very advantageous in real-world applications and on-site testing by the producers and regulating agencies. In this way, a capability for rapid verification of oil authenticity is completed correctly at production facilities, distribution centers, or even retail outlets; hence, minimizing reliance on centralized laboratories makes the method accessible even in the most remote areas. This study used some of the most common adulterants, such as sunflower oil, canola oil, corn oil, or soybean oil, but other, less common adulterants, considering their economic importance, will be considered in further investigations. In addition, an extended spectral library for potential adulterants could further enhance the robustness of this approach and ensure its wider applicability in edible oils. In general, this study has pointed out the great potential of FT-IR spectroscopy as a rapid, non-destructive, and low-cost technique for authenticity control. The proposed method identifies and characterizes adulterations that supply reliable detection of a number of fatty acids' predictions, satisfying the big current demands in the fight against food fraud, regulatory control, and the improvement of consumer trust. Such an approach bridges laboratory methodologies with practical quality controls of this product, thus meeting the practical needs of producers and regulating authorities.