## 3 Results and Discussion
### Phenolic Acids and Flavonoids Content
(2017) determined caffeic acid content within a range from 0.09 to 0.77 mg/100 g in the commercial honeys supplemented with bee bread at a level of 10% or 20%. [PERSON] et al. (2010) found only the traces of caffeic acid in Polish and Lithuanian be bread. Flavonoids are a known group of antioxidants present in honey and other bee products. Their content and type significantly determine the honey antioxidant activity. The bee bread addition is responsible for an increase in quercetin content in honey. Quercetin is a flavonoid with the highest share in the entire group of these compounds determined in the analyzed samples. The content of this flavonoid in honey with 25% addition of bee bread increased above 20 times, to the level of 0.868 mg/100 g (Table 2). This value is within the range (0.19-1.1 mg/100 g) reported by [PERSON] et al. (2017) for the honeys with 10% or 20% addition of bee bread. [PERSON] et al. (2017) did not find quercetin in bee bread, while [PERSON] et al. (2017) and [PERSON] et al. (2017) confirmed the presence of quercetin in bee bread, in the form of glycosides. The presence of quercetin in that bee product was also confirmed by [PERSON] et al. (2017), while [PERSON] et al. (2017) found traces of that flavonoid in Polish and Lithuanian bee bread. [PERSON] et al. (2017) determined quercetin levels  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Phenolic**} & \multicolumn{6}{c}{**Bee Bread Content (\%)**} \\ \cline{2-7}
**Acid/Flavonoid** & **0** & **5** & **10** & **15** & **20** & **25** \\ \hline Ferulic & 0.095 \({}^{\text{a}}\)\(\pm\) 0.005 & 0.091 \({}^{\text{a}}\)\(\pm\) 0.005 & 0.176 \({}^{\text{b}}\)\(\pm\) 0.006 & 0.192 \({}^{\text{c}}\)\(\pm\) 0.008 & 0.210 \({}^{\text{d}}\)\(\pm\) 0.005 & 0.229 \({}^{\text{e}}\)\(\pm\) 0.005 \\ Gallic & 0.217 \({}^{\text{a}}\)\(\pm\) 0.004 & 0.262 \({}^{\text{b}}\)\(\pm\) 0.019 & 0.301 \({}^{\text{c}}\)\(\pm\) 0.014 & 0.396 \({}^{\text{d}}\)\(\pm\) 0.010 & 0.471 \({}^{\text{e}}\)\(\pm\) 0.010 & 1.104 \({}^{\text{f}}\)\(\pm\) 0.034 \\ \(p\)-Hydroxybenzoic & 0.040 \({}^{\text{a}}\)\(\pm\) 0.003 & 0.059 \({}^{\text{b}}\)\(\pm\) 0.001 & 0.089 \({}^{\text{c}}\)\(\pm\) 0.002 & 0.102 \({}^{\text{d}}\)\(\pm\) 0.001 & 0.122 \({}^{\text{e}}\)\(\pm\) 0.002 & 0.140 \({}^{\text{f}}\)\(\pm\) 0.006 \\ Caffeic & 0.026 \({}^{\text{a}}\)\(\pm\) 0.000 & 0.061 \({}^{\text{b}}\)\(\pm\) 0.004 & 0.069 \({}^{\text{b}}\)\(\pm\) 0.002 & 0.079 \({}^{\text{c}}\)\(\pm\) 0.002 & 0.093 \({}^{\text{d}}\)\(\pm\) 0.004 & 0.159 \({}^{\text{e}}\)\(\pm\) 0.014 \\ \in bee bread in the range from 27.41 mg/100 g to 49.58 mg/100 g. The high quercetin level in bee bread directly influences its rising content in honey. Kaempfer was another flavonoid present and determined in the analyzed samples. Its content in honey amounted to 0.049 mg QE/100 g. The presence of that flavonoid in the honeys originating from Poland was earlier confirmed by [PERSON] et al. [7; 37] and [PERSON] et al. [9]. The bee bread addition at a level of 5% resulted in the increase in kaempfer level to 0.113 mg/100 g; whereas, its maximum level resulted in a ten-fold increase in that flavonoid (Table 2). An increase in kaempfer content in the honey supplemented with bee bread was lower than that determined for honey with bee pollen addition [16]. [PERSON] et al. [37] found a lower kaempfer content in the commercial honeys with 10% addition of bee bread, while the content of that compound was much higher in honeys with 20% addition of bee bread. [PERSON] et al. [45] and [PERSON] et al. [20] reported that content of kaempfer in bee bread ranged from 3.99 to 49.68 mg QE/100 g. [PERSON] et al. [22] found that kaempfer is the main flavonoid found in bee bread. [PERSON] et al. [17] and [PERSON] et al. [24] confirmed the presence of kaempfer in bee bread, in the form of glycosides. The high kaempfer level in bee bread led to an increase in its content in the studied honeys enriched with that bee product.