## 3 Results
### Physicochemical Properties of Powders
#### 3.5.5 Apparent Density and Loose Bed Porosity  
The apparent density (\(D_{ap}\)) of obtained buckwheat honey powders ranged from 1.42 \(\pm\) 0.02 to 1.51 \(\pm\) 0.00 g/cm\({}^{3}\) (Table 3). Generally speaking, the values are consistent with previous results presented in the literature concerning honey powders. [PERSON] et al. (2019) noted \(D_{ap}\) of multifloral honey powders spray dried at 180 and 80 \({}^{\circ}\)C with MD and MP as carrier agents ranging from 1.44 \(\pm\) 0.00 to 1.54 \(\pm\) 0.00 g/cm\({}^{3}\)[16]. [PERSON] et al. (2019) reported \(D_{ap}\) of honeybee and rapeseed honey powders spray dried traditionally and with the application of dehumidified air and with NUTRIOSE(r) as a carrier varying from 1.49 \(\pm\) 0.01 to 1.56 \(\pm\) 0.01 g/cm\({}^{3}\)[20]. Presented results revealed that there was a statistically significant effect of drying temperature and carrier content in variants where MD was applied. However, the influence of drying temperature could not be observed for variants where MP was used as a carrier, though the effect of the carrier content could be noted. Moreover, a statistically significant difference could be observed as well when comparing variants with the same carrier content but different carrier type, with the exception of variants spray dried traditionally at high drying temperatures (SDMD50 and SDMP50). In contrast to the earlier findings of [PERSON] et al. (2019), who noted higher values of \(D_{ap}\) in variants spray dried traditionally than in variants spray dried with the application of dehumidified air, a similar relationship was not observed in this paper [20]. It would seem to appear that a higher drying temperature increased the rate of evaporation, which in turn resulted in lower \(D_{ap}\) and more porous powders.  
The loose bed porosity (\(\varepsilon_{L}\)) of produced buckwheat honey powders varied from 50.5 \(\pm\) 0.6 to 67.8 \(\pm\) 0.8% (Table 5). Bed porosity is an important parameter in terms of a product's stability and its storage, as it describes the relative share of free spaces between particles that are filled with air. As a result, at higher porosity the compounds that are susceptible to oxidation are more likely to degrade [52]. The greatest \(\varepsilon_{L}\) was noted for variant DASMD75, which was due to the lowest \(D_{L}\) and highly conglomerated particles, as observed on SEM photographs (Figure 2). The Pearson negative correlation between \(\varepsilon_{L}\) and \(D_{L}\) was observed: powders with higher \(D_{L}\) had lower \(\varepsilon_{L}\) (Table A1).  
The results found in this study are lesser with respect to those reported in the literature. [PERSON] et al. (2020) produced honey powders of porosity ranging from 58.2 \(\pm\) 1.1 to 70.5 \(\pm\) 3.4%, using traditional spray drying and with the application of dehumidified air and decreasing carrier content, as presented in this paper [17]. [PERSON] et al. (2019), who applied the same spray drying methods to obtain honey powders, noted porosity varying from 63.3 \(\pm\) 0.7 to 72.5 \(\pm\) 0.92% [20]. In comparison to previous values, it seems likely that the type of a carrier and honey lowered \(\varepsilon_{L}\). The statistically significant difference between variants both with MD and MP with the same carrier content but spray dried at different drying temperatures could be observed (SDMD50 and DASMD50, SDMP50 and DASMD750). Lowering drying temperature as a result of the application of dehumidified air significantly lowered \(\varepsilon_{L}\). Moreover, variants where MP was used as a carrier in comparison with variants with MD were characterized by lower \(\varepsilon_{L}\). The utility of the application of dehumidified air and MP in buckwheat honey spray drying is thus proven with regard to powder porosity.