## 3 Results
### Physicochemical Properties of Powders
#### 3.5.4 Bulk Density and Flowability  
The loose bulk density (\(D_{L}\)) of obtained buckwheat honey powders varied from 0.51 \(\pm\) 0.02 to 0.73 \(\pm\) 0.01 g/cm\({}^{3}\) (Table 3). Obtained results differed to some extent from those of [PERSON] et al. (2015), [PERSON] et al. (2016) and [PERSON] et al. (2019) [12; 46; 47]. [PERSON] et al. (2015), who traditionally spray dried rapeseed and buckwheat honey powders, with gum Arabic as a carrier and with the addition of 1-2% of \(w/w\) NaCas, noted \(D_{L}\) from 0.43 \(\pm\) 0.01 to 0.61 \(\pm\) 0.01 g/cm\({}^{3}\) [12]. [PERSON] et al. (2016) observed \(D_{L}\) values of multifloral honey powders with maltodextrin as a carrier ranging from 0.42 to 0.59 g/cm\({}^{3}\) [46]. [PERSON] et al. (2019), who spray dried honey powder of stingless bee _Scapttorigona pectoralis_, reported a \(D_{L}\) of 0.33 g/cm\({}^{3}\) [47]. However, it should be highlighted that authors spray dried honey powders traditionally, using different carriers and different content and drying parameters than presented in this study. Moreover, the effect of carrier type can be noted: powders with MP had higher \(D_{L}\) than variants with MD. Generally speaking, high \(D_{L}\) indicates that there are fewer spaces filled with air between particles, which in turn lowers the risk of oxidative degradation of health beneficial compounds during powder storage. This implies that MP might be a better carrier than MD with regard to compound degradation during storage, regardless of carrier content and drying parameters. Normally, the \(D_{L}\) decreases with increasing particle size [48]. Contrary to expectations, obtained results did not confirm this relationship entirely, except for variants SDMD50 and DASMDD75. It should be noted that these variants had the biggest particle size (Table 3) as well as the most visible particle stickiness and agglomeration (Figure 2), which in turn led to the lowest \(D_{L}\). Interestingly, there was no statistically significant difference between variants spray dried traditionally with higher carrier content and variants spray dried at lower drying temperatures with lower carrier content, with both MD and MP applied as carriers (compare SDMD50 with DASMDD75, SDMP50 with DASMD75). The Hausner ratio (HR) is a parameter used to describe powder flowability, which indicates its quality. According to [PERSON] et al. (1984), obtained buckwheat honey powders showed good (\(<\)1.2) and average (1.2-1.4) flowability [49]. The results reported in this paper are consistent with previous studies on honey powder spray drying. The authors reported an HR of honey powders ranging from 1.30 \(\pm\) 0.04 to 1.38 \(\pm\) 0.02, from 1.27 to 1.36 and from 1.20 to 1.49 [17; 46; 41]. Broadly speaking, particle size diameter affects powder flowability; with increasing particle size diameter, flowability ameliorates, which is confirmed in this paper (excluding variant SDMD50, which presented significant stickiness) [49]. Powder of the best flowability (\(<\)1.2 HR) and greater \(D_{50}\) was noted for variant spray dried at low drying temperature and with the lowest carrier content (DASDMD75); this was an effect of particles' agglomeration (Figure 2), which ameliorated overall flowability despite high honey content. [PERSON] et al. (2014), who spray dried pink guava (_Psidium guajava_) powder, also observed that flowability deteriorated with increased drying temperature and MD concentration [50]. It should be highlighted that powders where MP was used as a carrier did not differ with regard to flowability. [PERSON] et al. (2020) reported as well that there was no effect of drying temperature (traditional spray drying and spray drying with the application of dehumidified air) on the flowability of honeybee honey when MP was used as a carrier, which was an effect of similar particle size in MP variants [17].