# Physicochemical and Antioxidant Properties of Selected Polish and Slovak Honeys
## 3 Results and Discussion  
### Physicochemical and Antioxidant Features of Honeys  
All analyzed 19 honey samples from Poland and Slovakia had moisture content below 20% and hydroxymethylfurfurral (HMF) content below 40 mg/kg; likewise, a diastase number higher than eight (Supplementary Materials Table S1), which is consistent with the standard of European Union [28]. The lowest diastase activity (expressed as diastase number) was observed in the case of rapeseed honeys from Poland. The highest value of this parameter was found in acacia honey from Slovakia, which was twice as large, as in the case of acacia honey from Poland. For all tested honeys, the sum of fructose and glucose, and the electrical conductivity of analyzed samples, were in line with standard requirements. The lowest conductivity exhibited rapeseed honeys (0.155 and 0.163 mS/cm for Polish and Slovak honeys, respectively) followed by acacia (0.192 and 0.232 mS/cm), lime (0.409 and 0.330 mS/cm), and forest honeys (1.032 and 1.155 mS/cm). The highest electrical conductivity revealed Polish forest honey what is characteristic for such type of honey (honeydew honey) [29]. The particular types of honey produced in Poland andSlovakia showed similarity in terms of glucose to fructose ratio (Supplementary Materials Table S1). It proves similarities of honey types obtained among selected countries. This similarity was also visible in the values of specific rotation. The most negative value of this parameter was shown by acacia honeys, which is related to the higher fructose content, while in the case of forest honeys (honeydew), the values of specific rotation oscillated around zero or was positive. Color of analyzed honeys was evaluated (Supplementary Materials Table S1), and results were expressed as \(L^{*}\), \(a^{*}\), \(b^{*}\). The browning index (\(Bl\), Equation (1)) was calculated from the above-mentioned parameters and used for better and easier characterization of differences between analyzed samples. The lowest value of \(Bl\) was evaluated for Slovak rapeseed honey (7.54). Polish rapeseed honey exhibited higher value (14.34) what was a consequence of higher \(b^{*}\) value reflecting a larger share of yellow color in overall color perception. An explanation of this observation may be the fact that the flowering period of rapeseed in Poland falls short before the acacia (_Robinia pseudoacacia_) bloom. Therefore, it is impossible to exclude the possibility of a small contamination of rapeseed nectar by nectar from another plant. Acacia honeys both from Poland and Slovakia had a similar \(Bl\) value. One of the most important functional properties of honey is antioxidant activity. Honeys differ in terms of floral source, and that is why they also vary in this functional feature. Antioxidant properties of honeys were expressed as Trolox equivalent antioxidant capacity (TEAC) and were measured both against ABTS\({}^{\bullet+}\) and DPPH\({}^{\bullet}\). Polish and Slovak honeys had similar TEAC measured against ABTS\({}^{\bullet+}\) within their own type with rapeseed honey as one exception. Polish rapeseed honey exhibited twice as much antioxidant activity as compared to the Slovak one. This can be explained by the slightly darker and more yellow color of this honey. It is noteworthy that the color of the honey is closely related with its antioxidant properties (Supplementary Materials Table S1) [30]. On the other hand, both rapeseed honey from Slovakia and Poland showed similar antioxidant properties measured against DPPH\({}^{\bullet}\), although the TPC value was higher, in the case of honey samples from Poland (Supplementary Materials Table S1). This may indicate a certain specificity of particular antioxidant activity assays [31]. The highest TEAC measured both against ABTS\({}^{\bullet+}\) and DPPH\({}^{\bullet}\) as well as the highest TPC showed sample of Polish forest honey (honeydew honey) (Supplementary Materials Table S1) what is characteristic for this type of product [29].