Determination of furanic compounds and acidity for Italian honey quality
The quality of honey is influenced by botanical origins and acidity. 5-Hydroxymethyl-2-furaldehyde (HMF) is a well-monitored indicator for freshness and quality, whereas no restriction is reported for 2-furfural. The aim of the study is the determination of these compounds in 21 Italian honey samples through high-performance liquid chromatography (HPLC). In order to validate the HPLC method, the detection and quantification limits (LOD and LOQ, respectively), recovery, precision (repeatability), and linearity were determined. The quantity of HMF extracted ranges from 3.35 to 43.21 mg/kg, and 2-furfural is found only in chestnut and wood samples in the range of 0.3–1.7 mg/kg. In addition, the effect of storage time effect was investigated for HMF, 2-furfural, and free and lactone acidities over a 4-month period. Finally, another compound was revealed and, on the basis of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, HPLC mass spectrometry, UV spectra, and chromatographic results, is hypothesized to be 2-(furan-2-methyl)-4-methoxyfuran-3-(2H)-one. The absence of any aldehyde group in the proposed compound is confirmed by the 2,4-dinitrophenylhydrazine spectroscopic method. Profiles of HMF, 2-furfural, and the hypothesized furanic compound have been outlined according to the floral origin of the honey.