## 3 Results and Discussion  
### Differential Scanning Calorimetry  
DSC enables quantitative and qualitative determination of physicochemical changes in heat flow in a sample during phase transition, such as melting [31]. [PERSON] et al. [32] report that stabilizers and gelling agents affect the water condition in food products. In Figure 1, an example of an ice melting curve of BMC sample is shown with indication of measured parameters of onset temperature (T\({}_{\text{onset}}\)) and peak temperature (T\({}_{\text{peak}}\)). Table 1 shows the results of DSC analysis of ice melting phase transition in buttermilk cheese in order to examine the behavior of water, which was measured after crystallization under controlled conditions with a scanning rate of 5 \({}^{\circ}\)C/min. During the cooling process (results not shown), peaks related to the liquid-solid exothermic phase transition were observed. At approx. \(-\)15 \({}^{\circ}\)C, the first-order transition occurred, corresponding to the crystallization of water, associated with a sharp and narrow peak. Using the cooling and heating procedure, it was possible to calculate from the melting curve the content of freezable water (FW), which was related to free water, as well as unfreezable water (UFW), namely bound water.  
It was determined that the percentage of FW in cheese samples ranged from 74.4% to 77.91%. The highest percentage of FW and lowest UFW was found in BMC/WPC and BMC/DPWP samples, where the remaining samples showed significant differences (BMC, BMC/SPWP) (\(p\)\(\leq\) 0.05). Significant differences were also observed in the mean values of peak temperatures (T\({}_{\text{peak}}\)) and onset temperatures (T\({}_{\text{onset}}\)), as well as ice melting enthalpies (\(\Delta\)H\({}_{\text{m}}\)). The lowest peak temperature was determined for BMC/SPWP sample (0.98 \({}^{\circ}\)C) and the highest for BMC/DPWP cheese sample (1.77 \({}^{\circ}\)C). The DSC results showed that the single heating process of WPC solution used for the production of cheese is necessary and optimal for the binding of water in cheese, since in the sample without heating (BMC/WPC), the amount of free water (FW) was higher, similarly as in the case of sample with a double heating of WPC solution (BMC/DPWP). [PERSON] et al. [33] reported that cottage cheese contains small globules of fat that are protected by protein layers, which may justify its higher melting point. According to [PERSON] and [PERSON] [31], the DSC method is an effective tool for determining and comparing the thermal properties of cottage  
Figure 1: DSC melting curve of BMC cheese sample showing ice melting peak. T\({}_{\text{onset}}\): onset temperature; T\({}_{\text{peak}}\): temperature at maximum heat flow value.  
cheese with different fat content. However, according to [PERSON] et al. [34], it is also possible to determine the thermal properties of whey protein concentrates and their modifications (caused by the heating process and/or the addition of soy lecithin) as a result of changes to the surface hydrophobicity of whey proteins. Thus, not only the ingredients of buttermilk (phospholipids or MFGM particles), but also the conditions of further processing can promote shaping rennet gel properties and model cheese manufacturing. [PERSON] et al. [35] showed that milk with raw cream buttermilk started to coagulate significantly faster than with buttermilk from pasteurized cream. This was not a result of pasteurization, but the ability of the rennet to hydrolyze. The deposition of denatured whey proteins and MFGM proteins on casein micelles may slow hydrolysis [35].