Determination of furanic compounds and acidity for Italian honey quality

Abstract

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.

Polyfloral honey from urban beekeeping: two-year case study of polyphenols profile and antioxidant activity

“…Results are displayed in Table 1. In the samples object of the present study, the pH values were in the range of 3.52–4.23, in accordance to those previously reported in polyfloral Italian honeys (Apericeno et al , 2018). The results showed significant difference among the average values only among different origin of honey harvested in 2019, where the urban honey had the highest value (4.16 ± 0.07) while the PA the lowest (3.47 ± 0.12), the urban being only significantly different in terms of the pH value of 2018.…”

“…The pH, HMF content, water content and sucrose content were determined according to the IHC (2009). Lactone, free and total acidities were determined with the volumetric method previously described in Apericeno et al (2018).…”

Characterization of Botanical Origin of Italian Honey by Carbohydrate Composition and Volatile Organic Compounds (VOCs)

“…In our chestnut honey, a significant level of furfural was observed ( Figure 5 c) in comparison to the other kinds of honey. Previous studies [ 56 ] reporting the concentration of furanic compounds in various monofloral and multifloral honeys indicated the presence of furfural only in chestnut honey, hypothesizing, differently from HMF, a botanical origin for this compound.…”

Insight into the Recent Application of Chemometrics in Quality Analysis and Characterization of Bee Honey during Processing and Storage

“…In a pioneering study covering the introduction of national legislative limits for Talh honey, the free acidity (FA) of Talh honey was determined from Talh tree leaves and flowers (30 ± 0.99; 34 ± 0.92 meq/kg) to bee crop (honey stomach) and unripe honey (43 ± 1.80; 72 ± 1.56 meq/kg) and finally to ripe honey (77 ± 1.28 meq/kg), [193], while the highest pH value was recorded in the leaves and kept decreasing as honey production proceeded, obtaining its lowest value in ripe honey (4.91 ± 0.06); (b) Effect of storage. Reports have shown a significant effect of storage on honey FA, pH, (p < 0.05), with FA increasing and pH decreasing with storage time [181,194,195]. In one kinetic study, exclusively dedicated to the variability of all the three parameters versus 30 months storage for honey stored at room temperature (15-25 • C), lactonic acidity found to increase by storage time (p < 0.05), even at a higher degree than FA increased or pH decreased [196], while in some cases lactonic acidity was slightly decreased, and total acidity was increased [181].…”

“…The principal organic acid in honey is gluconic acid derived from the activity of the glucose-oxidase enzyme on the glucose substrate, that is in equilibrium with δ-gluconolactone [179][180][181][182]. The gluconic acid level, for a specific honey species, is mostly dependent on the time elapsed between the collection of nectar and formation of the final honey by bees for obtaining the final density in the honeycomb cells, while glucose-oxidase activity becomes insignificant when the honey is thickened [183].…”