###### Abstract  
Among the variants of Greek honey, the most commonly available are pine, fir, thymme, and citrus honey. Samples of the above kinds of honey, identified according to European and Greek legislation, were studied using gas chromatography coupled with mass spectrometry (GC-MS) and the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic techniques. Two chemometric models were developed based on statistically significant volatile compounds (octane; 2-phenylacetaldehyde; 1-nonanol; methyl 2-hydroxybenzoate; 2-(4-methylcyclohex-3-en-1-yl)); nonanoic acid) and the 1390-945 and 847-803 cm\({}^{-1}\) spectral regions, mainly vibrations of fructose and glucose, combined with the stepwise linear discriminant analysis (stepwise LDA) statistical technique. In total, 85.5% of standard samples, and 82.3% through internal validation and 88.5% through external validation, were identified correctly using the GC-MS-stepwise-LDA chemometric model. The corresponding results for the ATR-FTIR-stepwise-LDA chemometric model were 93.5%, 82.5%, and 84.6%. The double validation (internal, external) enhances the robustness of the proposed chemometric models. The developed models are considered statistically equivalent, but FTIR spectroscopy is simple, rapid, and more economical. honey; botanical origin; unifloral; authentication; volatile compounds; GS-MS/SPME; ATR-FTIR spectroscopy +
Footnote †: journal: Applied Soft. 2021, 11, 40.  
overall honey production in Greece. In comparison, citrus accounts for 15%, thyme for 10%, and fir for 5% [4]. Commercially produced honey is particularly susceptible to adulteration, fabricated declarations of botanical origin, and multiple other forms of fraudulent conduct. This profiteering and deception frequently damage the interests of producers, suppliers, and consumers. Hence, there is a clear need for techniques capable of reliably ascertaining the monofloral botanical origin of honey. The botanical origin of honey can be determined in accordance with its melissopalynological and physicochemical properties [5; 6; 7; 8]. However, these techniques are expensive, time-consuming, and require specialized staff. Authentication of honey can be carried out with different analytical techniques, such as high-performance liquid chromatography with electrochemical detection (HPLC-CCD) [9], stable isotopic analysis [10], nuclear magnetic resonance (NMR) [11], electronic nose [12], and gas chromatography coupled with mass spectrometry (GC-MS) [13] Furthermore, techniques such as Fourier transform infrared (FTIR) [14], near-infrared (NIR) [15], and Raman spectroscopy [16] can also be used. In recent years, there has been a continuous effort to develop more of these techniques coupled with multivariate statistical analysis [17; 18]. Among the above techniques, the determination of volatile compounds based on solid-phase microextraction (SPME) coupled with GC-MS has been adopted to identify the botanical origins of Greek honey [13; 19; 20]. Nevertheless, parameters such as polarity fraction, the number of volatile compounds, and chemometric techniques could directly impact the results of discrimination. In addition, there is a growing, constant need to develop practical, reliable, and rapid methods. To the best of our knowledge, there have been no reported studies using total reflectance (ATR)-FTIR spectroscopy for discrimination of Greek honey of different botanical origins. Multivariate statistical analysis in combination with previously outlined analytical methods could in some cases be a powerful tool for the botanical authentication of honey. To be robust, a statistical model must possess many honey sample standards from every botanical origin, known as a \"calibration set\", in addition to a \"test set\" which can be used for validation. Furthermore, the composition of honey means that it is necessary to generate a constant and accurate chemometric paradigm in accordance with monofloral samples, which can be measured against existing legislation.