## 3 Results and Discussion  
### Water Content, Water Activity, and Hygroscopicity of Insect Powders  
Understanding the water content in dry materials is crucial for determining their durability, storage conditions, and quality and influencing how they will be used in further production. A significantly lower water content was found for insect powder obtained by the convective method (Table 1). In general, infrared drying improves water removal from the material [33]. However, in this case, the formation of a hard crust on the surface of the insect's tissue was observed due to faster surface water evaporation than the internal water migration, which, in effect, limited water evaporation [34]. What's more, present fat was able to migrate more efficiently to the surface due to channels formed after denaturation and reorganization of the myofibrillar protein [35], which was observed for infrared dry-roasted almonds [36]. On the surface, fat creates a layer that impedes the evaporation of water. Additionally, it is suggested that the result is attributable to the interaction between components, as residual water present in the subsequent dehydration stage was bound [37], thereby providing a higher water content. Due to the material's well-absorbed infrared radiation and fast internal temperature increase, proteins undergo denaturation, leading to higher exposure to hydrophilic sites and, thus, a greater ability to absorb water molecules [38]. Subsequently, denatured or damaged proteins formed larger structures--aggregates [39]--and it was more difficult to remove water molecules from them during drying. Furthermore, the smaller particles of the IR-CD-dried insect powder (see Table 3) provided a larger surface area that favored their interactions. The fat on the surface of the particles [26] and free water transformed from immobilized water due to infrared radiation [40] causes the formation of liquid bridges and sticking. It thus impedes the evaporation of water during the water content measurement. As a result, this may have influenced the higher water content of the test sample. Water activity informs about the available water (free and partially bound) in the material and its susceptibility to microbial growth and exposure to chemical reactions [31]. The minimum water activity required for the growth of most bacteria is 0.91, and for yeasts and filamentous fungi, it is 0.88-0.80. However, there are organisms better adapted to water deficit, such as halophilic bacteria, osmotolerant yeasts, and xerophilic fungi. These organisms can develop in an environment with an aw of 0.75-0.60. It is assumed that microbial growth does not occur at an activity lower than 0.60 [41]. Despite a significantly lower water content for insect powder obtained by the convective method, the water activity values for both powders are close to 0.2 (Table 1). It indicates microbial stability (water activity below 0.6), and the slowest lipid oxidation due to water activity of 0.2-0.4 corresponds to the monolayer moisture content [42; 43]. A higher water activity of IR-CD-dried powder was related, same as for water content, to interactions between protein and water molecules, as well as higher free water content released from the myofibrillar network of the powder particles [40]. The hygroscopicity of black soldier fly larvae powders is presented in Table 1. The powder received by convective drying (CD) exhibited a significantly lower hygroscopicity after 72 h of water vapor adsorption of water activity of 1.0. The powder properties, such as particle size distribution and surface area, influence hygroscopicity [44]. Applying the IR-CD method allows for obtaining smaller powder particles (Table 3) and an increased number of adsorption sites. Hence, insect powder could bind more water during the water vapor adsorption. Apart from that, the hygroscopicity of tested powders was influenced by the chemical compositions (CD-dried powder: 32.02 and 38.94 g/100 g d.m. of protein and fat, IR-CD-dried powder: 29.85 and 43.89 g/100 g d.m.