## 3 Results and Discussion
### Quality Parameters  
Table 4 lists values for the selected parameters characterizing the commercial quality of honeys. The content of water-insoluble substances is one of the parameters of honey quality. These substances include pollen, bee bread, and propolisis, fragments of bees, and cells of algae and fungi. The water-insoluble substances in studied honey were at a level of 0.06 g of per 100 g, so this met the relevant requirements [46; 47]. The supplementation of honey with bee bread significantly contributed to an increase in water-insoluble substances. After the maximum addition of bee bread of 25%, their content was 7.75 g per 100 g. [PERSON] et al. [48] reported that addition of bee products to multifocal honey may result in even a four-fold increase in the insoluble solid substances content. Honey acidity results from the presence of organic acids, mainly produced from glucose with the participation of relevant bee enzymes. Too-high free acidity may be a sign of growth of microorganisms and fermentation of honey. Free acidity was 22.9 mval/kg for the multifloral honey, and this confirms the earlier literature data for multifloral honeys originating from Poland [48] and meets the relevant legal requirements [46; 47]. The bee bread addition to honey led to a significant increase in free acidity. At a 5% addition, free acidity increased to 57.1 mval/kg, and with the highest addition of 25%, it was as high as 187.1 mval/kg (Table 4). Bee bread contains both organic acids, including gluconic and lactic acids that are produced during fermentation, as well as large quantities of amino acids, e.g., proline (Table 4), which increases the acidity of honey with bee bread addition. As [PERSON] et al. [49] reported, free acidity of bee bread can be at a level of 543 mval/kg. The conductivity of honey solution depends mainly on the mineral and organic acids content. The quality requirements impose the maximum value of conductivity for nectar honeys at a level of 0.8 mS/cm [46; 47]. The specific conductivity of studied honey was measured at 0.50 mS/cm (Table 4), which met the legal requirements. The bee bread addition led to a proportional increase in specific conductivity, which was 1.33 mS/cm for the maximum concentration of bee bread (25%). It indicates that minerals and organic acids are introduced along with bee bread, which also increases free acidity. As [PERSON] et al. [49] report, the ash content of bee bread is 3.4 g/100 g.  
The sum of fructose and glucose in nectar honey cannot be lower than 60 g/100 g of honey [46; 47]. In the honey under study, the sum of glucose and fructose content was 65.2 g/100 g; therefore, it conforms to legal requirements [46; 47]. The bee bread addition contributed to a significant drop in the sum of glucose and fructose (Table 4). In the case of the highest bee bread concentration, the sum of glucose and fructose dropped to  
Figure 4: The acceptability results evaluation of the studied honey and samples supplemented with bee bread. 53.3 g/100 g. Bee bead contains fewer simple sugars than honey itself. As [PERSON] et al. [49] reported, bee bread contained 19.7 g of fructose, and only 8.8 g of glucose per 100 g. For this reason, when part of the honey is replaced by bee bread, the level of these sugars decreases. Sucrose content, being another quality requirement for honey, may not exceed 5 g/100 g [46; 47]. The studied multifloral honey met this requirement (Table 4). As bee bread does not contain a significant amounts of sucrose [49], adding it to honey does not matter here. Another factor which influences the quality of honey is the presence of 5-hydroxymethyl-lfurfurral (5-HMF), the elevated content of which indicates that the honey was improperly stored, overheated to facilitate its filtration, or adulterated with inverted sugar. In case of multifloral honey, the content of HMF was 10.76 mg/kg, and the addition of bee bread did not significantly influence the results. That fact confirms previous data on the commercial honey samples enriched with bee products [47].