Preliminary Characterization of Bulgarian Forest Honeys: Oak Honeydew and Coniferous Varieties

The objective of this work was to determine and compare a comprehensive set of quality markers, including main physicochemical properties and element profiles, in samples of Bulgarian oak honeydew honey (OHH) and coniferous honeydew honey (CHH). This investigation utilized a total of seventeen honey samples from Bulgaria harvested in 2022. The sample set comprised ten oak honeydew honey samples, sourced from the Burgas region, and seven coniferous honeydew honey samples obtained from the Smolyan region. The parameters of OHH samples varied within the following ranges: color (80-134 mm Pfund), water content (15.20-18.40%), electrical conductivity (0.80-1.33 mS/cm), specific optical rotation (2.25-12.50 [α]D20), pH (3.92-4.50), total acidity (29.80-36.80 meq/kg), diastase activity (18.36-27.58 Gothe units), invertase activity (56-196 U/kg), proline content (155-477 mg/kg), and hydroxymethylfurfural (3.28-8.94 mg/kg). The CHH samples gave the following results: color (40-87 mm Pfund), water content (16.40-19.00%), electrical conductivity (0.80-1.26 mS/cm), specific optical rotation (-17.50-(-11.50 [α]D20)), pH (3.40-3.75), total acidity (25.80-39.40 meq/kg), diastase activity (23.15-26.05 Gothe units), invertase activity (69-138 U/kg), proline content (287-651 mg/kg), and hydroxymethylfurfural (1.50-3.96 mg/kg). The elements Ca, Cu, Fe, Mg, and Mn were determined by Flame Atomic Absorption Spectrometer (FAAS), while Flame Atomic Emission Spectrometry (FAES) was used for K and Na determination. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) analysis was used to assess six elements (Al, Ba, Co, P, Sr, Zn). The elements Cd, Ni, and Pb were determined by Electrothermal Atomic Absorption Spectrometry (ETAAS). Potassium is the most abundant macro element in all investigated samples ranging 2332-2370 µg/g in CHH and 1846-1878 µg/g in OHH. Other examined elements are in the following descending order, Mg > P > Na > Ca > Mn > Al > Fe > Zn > Cu > Ba > Sr, presenting in µg/g levels, while Pb > Ni > Co > Cd are present in µg/kg levels. This work constitutes the first report on the physicochemical parameters and chemical elements of coniferous honeydew honey from Bulgaria.