Characterization of unifloral Italian (Piedmont region) honeys by headspace solid phase microextraction coupled to gas chromatography–mass spectrometry

Background: The characterization of five different types of Italian unifloral honeys was performed by means of headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry. The main volatile compounds of the honeys were identified and semi-quantified. Pattern recognition methods such as principal component analysis (PCA) and k-nearest neighbors (k-NN) were performed to classify honey samples with different botanical origins, and identify the most discriminating parameters. Results: More than 100 of compounds were unambiguously identified in the honeys sampled. Methyl salicylate was present in honeydew honeys only, and this permitted to differentiate this kind of honeys from the others. Dandelion honeys featured high levels of nitriles, while lime tree honeys displayed the presence of carvacrol and of the terpenes cis and trans-p-mentha-2,8-dien-1-ol. Acacia honeys did not display potential chemical markers but were characterized by low levels of benzaldehyde and high levels of cis-linalool oxide. Chestnut and rhododendron honeys did not show a volatile profile markedly different from those of other honeys. Application of PCA and k-NN methods did not allow a complete classification of honeys of different botanical origin on the basis of their volatile profile. Conclusion: Unifloral honeys from Piedmont (Italy) displays a rich and variegate profile of volatile compounds, some of which are candidates as markers. Nonetheless, to classify honeys, further studies are necessary likely comprising a larger set of samples and the determination of different chemical parameters in conjunction with volatile compounds.