## 3 Results and Discussion
### Components and Properties of Goat's Milk with Permeate after Enzymatic Conversion of Lactose
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameters** & **M** & **M/GOS** & **M + P** & **M + P/GOS** \\ \hline Freezing point (\({}^{\circ}\)C) & \(-0.5610\pm 0.001\)\({}^{\mathrm{a}}\) & \(-0.5580\pm 0.002\)\({}^{\mathrm{a}}\) & \(-0.5593\pm 0.001\)\({}^{\mathrm{a}}\) & \(-0.5586\pm 0.003\)\({}^{\mathrm{a}}\) \\ Density, in 20 \({}^{\circ}\)C (kg/m\({}^{3}\)) & 1.031 \(\pm\) 0.001 \({}^{\mathrm{a}}\) & 1.030 \(\pm\) 0.000\({}^{\mathrm{a}}\) & 1.032 \(\pm\) 0.000\({}^{\mathrm{a}}\) & 1.031 \(\pm\) 0.001\({}^{\mathrm{a}}\) \\ Viscosity (mPas) & 3.12 \(\pm\) 0.03\({}^{\mathrm{a}}\) & 3.13 \(\pm\) 0.02 \({}^{\mathrm{a}}\) & 3.15 \(\pm\) 0.01 \({}^{\mathrm{a}}\) & 3.14 \(\pm\) 0.02 \({}^{\mathrm{a}}\) \\ Conductivity (\(\Omega^{-3}\)/cm) & 6.19 \(\pm\) 0.02\({}^{\mathrm{a}}\) & 6.15 \(\pm\) 0.03\({}^{\mathrm{a}}\) & 6.17 \(\pm\) 0.02 \({}^{\mathrm{a}}\) & 6.18 \(\pm\) 0.01 \({}^{\mathrm{a}}\) \\ Water activity (\(\cdot\)) & 0.9839 \(\pm\) 0.003\({}^{\mathrm{a}}\) & 0.9830 \(\pm\) 0.002\({}^{\mathrm{a}}\) & 0.9829 \(\pm\) 0.004\({}^{\mathrm{a}}\) & 0.9832 \(\pm\) 0.002\({}^{\mathrm{a}}\) \\ \hline \hline \end{tabular} M—goat’s milk; M/COS—goat’s milk after enzymatic conversion of lactose. M + P–goat’s milk with permeate; M + P/GOS—goat’s milk with permeate after enzymatic conversion of lactose. Values represent mean \(\pm\) SD (\(n=7\)); SD—standard deviation; \({}^{\mathrm{a}}\), different letters with mean values in a row indicate statistically significant differences at the level \(\alpha=0.05\).  
\end{table} 
Table 3: Physicochemical properties of goat’s milk and goat’s milk with permeate after enzymatic conversion of lactose. formation of low-molecular-weight components. The advantage of oligomers was observed at higher temperatures. The formation of oligomers, dimers, and monomers significantly changed the taste and properties of the food product. Additionally, heat treatment changed the prebiotic effect. Presumably, the greater stability of GOS in the mixture with permeate results from the presence of the ionic system associated with salts, such as phosphorus, calcium, sodium, and potassium. Their presence in amounts different from those in milk may stimulate the process of GOS degradation. Permeate is a source of minerals such as sodium and potassium and also contains calcium, phosphorus, and magnesium [36]. [PERSON] et al. [39] showed that permeate with a protein content of 0.2 g/100 g contains 0.3-0.4 g/kg phosphorus, 0.2 g/kg calcium, and 0.1 g/kg sodium. These authors determined these minerals in milk with protein contents of 3.4 g/100 g, 1.6 g/kg, 1.2 g/kg, and 0.4 g/kg. On the other hand, [PERSON] et al. [31] determined that permeate contained twice the protein content (0.39%): 0.44 g/kg, 0.32 g/kg, and 0.38 g/kg, respectively. Permeate with a protein content of 0.56%, tested by [PERSON] et al. [40], contained 0.401 g/kg phosphorus and 0.254 g/kg calcium. However, as [PERSON] et al. [31] showed, the separation of minerals in the permeate depends, among other things, on the diameter of the pores in the membranes. [PERSON] et al. [32] also reported a significant difference in the potassium content. There was more of it in the permeate (2639.3 mg, calculated on a total solids basis) than in milk (1845.1 mg, calculated on a total solids basis). Performing a partial lactose hydrolysis reaction causes the accumulation of glucose and galactose. [PERSON] and [PERSON] [14], when analyzing GOS synthesis, did not notice a significant reduction in the total GOS efficiency in acid whey solutions compared with the reaction in buffered lactose solution, and the GOS produced had a greater structural diversity. The thermally induced decomposition of the studied carbohydrates was explained by a proton catalytic process. Protons could originate from the moisture of the sample. The addition of water to the double bond reformed the glycosidic protonated hydroxyl group, and the neutral form of the second fragment was produced by proton elimination [13].