## 3 Results and Discussion  
### Powdered Infant Formula Properties  
When determining the raw material composition of the mixtures, the fat content in the finished products was taken into account. The fat present in the mixtures came mainly from the powdered milk and n-3 and n-6 fatty acid preparations. The agglomeration process improves the physicochemical properties of the modified milk powder. Mixtures M1 and M2 were subjected to an agglomeration process using various wetting liquids. One agglomerate was obtained from the M1 mixture. Two agglomerates were obtained from the M2 mixture, while no agglomerate was obtained from the M3 mixture. The particle size distribution plays a special role because it both indicates a relationship with the functional properties of the powder and determines the characteristics of the material during further operations and processes, e.g., pneumatic transport, dosing, and packaging [30]. Figure 1 shows the particle size distributions of mixtures M1, M2, and M3, differing in the contents of the milk powder and lactose. The values of the median diameters, D\({}_{50}\), from the particle size distributions for the volume fractions of the tested mixtures were 83.2 \(\upmu\)m for mixture M3 and 101.7 \(\upmu\)m for the M1 and M2 mixtures (Figure 1). Mixture M3 was characterised by a lower particle diameter. Its main ingredients were lactose and casein (Table 1). Mixtures M1 and M2 were characterised by different ingredient compositions. The particle size distributions of these mixtures were the same (Figure 1). They were characterised by a higher median diameter, D\({}_{50}\). The values of the median diameters, D\({}_{90}\), from the particle size distributions of the tested mixtures ranged from 164.2 for the M1 and M2 mixtures to 181.9 \(\upmu\)m for the M3 mixture. Mixtures M2 and M3 were characterised by similar ingredient compositions. Whey proteins (5%) were added to the M2 mixture and casein (10%) to the M3 mixture. The particle size distributions of the individual mixtures were influenced by the particle sizes of the components of these mixtures. There was no significant effect of the addition of n-3 and n-6 fatty acid preparations on the particle size distributions of the mixtures. The particle size distribution of the powdered infant formula changed after the agglomeration process. In Figures 2 and 3, the influence of the agglomeration of the mixtures on their particle size distribution can be observed. The material ingredient compositions of the agglomerates and wetting liquids are presented in Table 2. The differences between the median diameters, D\({}_{50}\) and D\({}_{90}\), of the mixtures and agglomerates were statistically significant, while the differences between the agglomerates obtained from the same mixture using different wetting liquids (maltodextrin and water) were statistically insignificant. The type of wetting liquid (maltodextrin or water) had no influence on the particle size distribution of the agglomerates (Figure 3). The surface moistening of particles with water has a significant impact on the increase in the particle size distribution during agglomeration, while the carbohydrate content in the wetting liquid has a lower impact. This was demonstrated in research by [PERSON] et al. [31] on the agglomeration process of lactose and mannitol using ethyl alcohol and water as wetting solutions. Additives to the moisturising solutions included, among others, hydroxympropyl cellulose, polyvinylpyrrolidone, and selected surfactants. A similar relationship was demonstrated by [PERSON] [32], who examined the influence of the glassy state of amorphous food powders (e.g., maltodextrin, tomato powder, coffee, and baby formula) on the possibility of their agglomeration [33]. Figure 1: Particle size distributions of powdered infant formulas (mixtures).