## 3 Results and Discussion
### Influence of Storage on Content of Fatty Acids Extracted from Infant Formulas  
The fatty acid composition was determined in the studied mixtures and agglomerates. The presence of fatty acids derived from milk powder, such as oleic (C18:1c) and linoleic (C18:2c), was observed in the powdered infant formulas. Figures 7-9 present the contents of fatty acids in the studied infant formulas (mixture), fresh and after six months of storage. Table 5 shows the percentage differences in the contents of fatty acids in the powdered infant formulas \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type of Mixture** & **Fat Content (\%)** & **Agglomerate** & **Fat Content (\%)** \\ \hline M1 & 19.8 \(\pm\) 0.1 \({}^{\text{a}}\) & A1(M1) & 20.3 \(\pm\) 0.2 \({}^{\text{a}}\) \\ \hline M2 & 14.7 \(\pm\) 0.1 \({}^{\text{b}}\) & A2(M2) & 14.6 \(\pm\) 0.2 \({}^{\text{b}}\) \\ \hline M3 & 14.2 \(\pm\) 0.1 \({}^{\text{b}}\) & A3(M2) & 14.7 \(\pm\) 0.1 \({}^{\text{b}}\) \\ \hline \end{tabular} Values represent means \(\pm\) standard deviations. Data denoted by the same lowercase letters are not statistically different (\(\alpha\) = 0.05) in terms of different rows (\(p\) < 0.05) by [PERSON]’s test.  
\end{table} 
Table 4: Fat contents in mixtures and agglomerates of powdered infant formulas. Figure 8: Fatty acid compositions in fat extracted from fresh and stored powdered infant formulas M2 (mixture). Data marked with asterisk (*) are statistically different (\(\alpha\) = 0.05) in terms of storage. Figure 7: Fatty acid compositions in fat extracted from fresh and stored powdered infant formulas M1 (mixture). Data marked with asterisk (*) are statistically different (\(\alpha\) = 0.05) in terms of storage. Figure 9: Fatty acid compositions in fat extracted from fresh and stored powdered infant formulas M3 (mixture). Data marked with asterisk (*) are statistically different (\(\alpha\) = 0.05) in terms of storage. Particular attention was paid to those acids that were added to the Ropufa '10' n-3 and Ropufa '10' n-6 preparations. The main ingredients of the Ropufa '10' n-3 preparation were \(\alpha\)-linolenic acid (C18:3 n-3) and docosahexanoic acid (C22:6 n-3). In the Ropufa '10' n-6 preparation, the main ingredient was \(\gamma\)-linolenic acid (C18:3 n-6). In all the analysed samples, after a 6-month storage period, the share of all the unsaturated fatty acids decreased. [PERSON] et al. [39] studied whole milk powder particles (instant) using confocal and transmission electron microscopies. They found that during drying, protein particles (casein and lactoglobulin) are partially denatured and produce \"hairy ball\" structures. These structures form bridges with the fat surface, which leads to the fat being surrounded by proteins and forming a cluster. The protein coat (cluster) protects fats against the influence of unfavourable external conditions. Lactose (in its amorphous state) protects polyunsaturated fatty acids against environmental influences. [PERSON] et al. [40] studied the effects of sugars (lactose and trehalose) used to microencapsulate milk fat emulsions stabilised with sodium caseinate and whey proteins. They found that the addition of a small amount of lactose combined with proteins creates a protective layer on the particle surface. This layer protects the fat on the surface of the powder particles. [PERSON] and [PERSON] [41] stated that sugars act as a filler in the formation of powder particles. Lactose, in its amorphous form, seals the clusters it produces with milk proteins during spray-drying [39; 42; 43]. The structures created in this way protect fats against the influence of unfavourable external factors causing oxidation. The contents of saturated fatty acids (Figures 7-9) in the analysed mixtures of powdered infant formulas ranged from approximately 40 to 55%. The presence of saturated fatty acids is a natural phenomenon: they come from milk fat. However, the total content of polyunsaturated fatty acids was the highest for the M2 mixture, 41.2%.