## 3 Results and Discussion
### Physical and Emulsifying Properties of B. edulis POWDERS
On the other hand, studies have shown that the presence of liquid/water at a certain content on the particle surface may decrease the van der Waals interaction and improve flowability due to capillary forces, which will bind particles together [22]. This may further explain the better flow characteristics of the hereby investigated mushroom dried by HAD, which had a slight greater water content (by \(\sim\)11%) than that of the sample dried by CVD. Solubility and WSI are key physical characteristics of food powders, measuring the ability of powders to dissolve in water and form a homogeneous solution [23; 26]. The WSI value of HAD samples was lower (24.688 \(\pm\) 2.670%) than that of CVD samples (28.525 \(\pm\) 1.475%). Apart from some factors affecting the powder solubility, e.g., type of drying, powder particle size, and hydrophobic groups, the lower solubility observed in HAD samples might be due to the higher moisture content and different distribution of water molecules into the powder, which may lead to physical chemical changes, such as the formation of hydrates and aggregates. It has been demonstrated that solubility and bulk density are inversely correlated [24], a similar trend being observed for both investigated mushroom powders as indicated in Table 1.  
Regarding the RR, samples dried by HAD showed higher values (4.020) compared to mushrooms dried by CVD (3.012). The rehydration of powder is a multi-step process consisting of water absorption, water transfer to the porous structure, water distribution within the solid matrix, solid matrix swelling, and solids' dissolution into the aqueous medium [27]. The results on the functional properties of _B. edulis_ powders are presented in Figure 1, which comparatively depicts the emulsifying activity and stability indices, EAI and ESI, respectively, for the mushroom powders obtained by the two investigated drying procedures, HAD and CVD. Samples dried by CVD procedure showed slightly larger values of EAI (4.963 \(\pm\) 0.828 m\({}^{2}\)/g) and ESI (34.406 \(\pm\) 7.701 min) than values of EAI (4.687 \(\pm\) 0.923 m\({}^{2}\)/g) and ESI (33.741 \(\pm\) 7.510 min) for HAD samples, indicating a better emulsion stability of CVD samples. Figure 1: Emulsifying activity index (EAI) and emulsion stability index (ESI) of _B. edulis_ powders according to different drying procedures. The emulsifying properties, described in the literature by EAI and ESI indices, of different mushroom powders (_A. bisporus_, _Pleurotus gesteranus_, _Coprius atrimentarius_) or their extracted individual compounds, indicate the ability of their biomolecules (mainly proteins, but also polysaccharides/\(\beta\)-glucans) to form an emulsion [15; 28; 29] or improve the emulsion characteristics of further developed mushroom-powder-based products, such as meat [15]. In our investigation, the observed differences of EAI and ESI might be explained by the presence of both hydrophobic and hydrophilic residues, probably exposed to a different extent due to the distinct types of drying, which interact with the oil and aqueous phases, respectively. Similar ESI values but much higher EAI values were obtained for a protein solution at pH 7, the investigated proteins being isolated through different precipitation procedures from _Pleurotus gesteranus_ dried mushrooms [28]. The study of [PERSON] et al. [15] reported higher EAI and ESI values of _A. bisporus_ mushroom powders, 61.47 \(\pm\) 0.26 m\({}^{2}\)/g and 42.87 \(\pm\) 0.90 min, respectively, the obtained values being significantly increased due to the applied agglomeration process using top-spray fluidized bed. To our knowledge, no published study has been found on _B. edulis_ emulsifying properties determined using the spectrophotometric method and expressed by EAI and ESI, so that the hereby obtained results could not be compared to ones reported in the literature.