## 3 Results and Discussion
### Surface hydrophobicity and Bulk Density  
Surface hydrophobicity is essential because it impacts the functional characteristics of a protein's surface, including properties like foaming, as well as interactions with lipids and other proteins [24; 27; 34]. Table 1 shows the changes in the surface hydrophobicity of the various BSF larvae protein isolates. It is evident that salt treatment has a substantial influence (\(p<0.05\)) on the surface hydrophobicity when compared with the untreated sample (AAF). Moreover, there were significant differences between AAF and AAFSI (1056.41 and 1021.37, respectively), which were significantly (\(p<0.05\)) higher than those of the salting-out proteins (Table 1). During alkaline extraction and acid precipitation, proteins may partially unfold, exposing more hydrophobic residues on the protein surface and increasing total hydrophobicity [35]. The surface hydrophobicity of AAFSO and AAFSISO was discovered to be nearer to the reported values for whey protein (468.0); both isolates had a higher value than whey protein [36]. This is attributed to partial denaturation and subsequent aggregation of hydrophobic groups, which is consistent with previous observations [37]. The higher surface hydrophobicity may result in enhanced protein functionality due to changes in interfacial or surface tension. According to [14], protein hydrophobicity increases as a result of the exposure of hydrophobic groups and regions enclosed within the molecules to the more polar surrounding environment, due to protein denaturation to a certain extent. On the other hand, a high concentration of salt can enhance surface hydrophobicity owing to the salting-out mechanism, which breaks the hydration layer on the surface and disrupts the charge balance of protein molecules. One study [38] found that surface hydrophobicity increased with increased solubility when working with soy protein isolates. This suggests that aggregating proteins are more hydrophobic and have buried hydrophobic zones inside their structure, resulting in soluble aggregates with low surface hydrophobicity. These findings may be limited by the concentration of salt ions and cannot promote competition with protein molecules in binding with water molecules, leading to aggregation of the protein and ultimately increased hydrophobicity. These findings could explain the improved solubility of salted-out proteins [12] as shown in Figure 2.  
Bulk density is a crucial property employed to characterize protein products, and it holds substantial significance for both economic and functional reasons [39]. However, there were notable variations in bulk density among the BSF larval isolates, with the exception of AAF and AAFSO, as shown in Table 1. The bulk density of AAF was 1.23 g/mL, while the salt-treated isolates had values of 0.99 g/mL (AAFSI), 1.15 g/mL (AAFSO), and 1.52 g/mL (AAFSISO), respectively. Among the concentrates, AAFSI had a significantly (\(p<0.05\)) lower bulk density than the salt-extracted concentrate. Furthermore, the bulk density of AAFSISO was significantly (\(p<0.05\)) higher than that of AAFSO, which may be attributed to the finer particle size of the salt. What is interesting is that the addition of NaCl significantly decreased the bulk density of the BSF larvae protein, dropping from 1.23 mg/L to 0.99 mg/L, while the addition of ammonium sulfate resulted in a significant increase in bulk density (Table 1). One possible explanation could be that NaCl increased the solubility of the BSF larvae proteins, leading to a more dispersed or diluted protein solution with a lower bulk density. The reduction in protein bulk density is attributed to the modification of protein structure [40]. Proteins with low bulk density are advantageous for transportation and distribution, as they are easier to transport and distribute [41]. These findings are consistent with that of [42], who measured the bulk density of protein concentrates prepared from Hernelia illucens, Macrotermes subhylanus, and Gonimbrasia belina, ranging from 0.51 to 0.64 g/mL.