## 4 Results and Discussion
The bands with a maximum of \(\sim\)1144 cm\({}^{-1}\) and most of all with a maximum of 1047 cm\({}^{-1}\) are attributable to the vibrations of the C-O groups in the characteristic C-O-C connection. They are amplified by the vibrations from fat fractions. The area for this type of sample from about 1050 to 950 cm\({}^{-1}\) is also the C-O in C-OH group or COO- and C-C stretching vibrations in the carbohydrate structure. The area below 950 cm\({}^{-1}\) is the vibration characteristic of theomeric region of carbohydrates or deformation vibrations of the C-H and C-C groups [40; 41; 42; 43; 44; 45]. It is worth noting that slight changes in the vibrations from this region of the bands often indicate modifications in the bonds of the carbohydrate fractions. In the tested samples, this region, apart from the change in the intensity, does not differ much for individual spectra. Based on the analysis performed using FTIR, the subtle differences in the spectra are worth emphasizing, which, however, quite strongly confirm the results of previous studies. The differences, primarily in the intensity between the spectra in several areas, seem to be particularly visible. These differences are visible in the region of C-H vibrations in the -CH\({}_{2}\) groups and the carbonyl group C=O, and in the region of C-C, C-H, and C-O vibrations in the area of the fingerprint. Changes in these areas correlate with changes in the treatment used, i.e., traditional pasteurization or ultrasound pasteurization. These factors resulted in a marked decrease in the intensity of vibrations in the regions characteristic of the fat contents and a slight increase in the intensity of these vibrations, which are characteristic of the carbohydrate content. These changes seem to be closely related to the processing factors used in ice cream production. A much higher intensity of these changes can be observed in the spectra after ultrasound pasteurization. Ice cream has a very complex structure, with many phases affecting its quality, texture, and physical properties, including shape retention and structure collapse during melting. The ingredients are water, fat, fat-free milk dry matter (casein micelles, whey proteins, lactose, and milk salts), sugars (sucrose and partially hydrolyzed starch, including glucose, maltose, and higher saccharides), stabilizers, and emulsifiers, and air is added prior to dynamic freezing. All these elements contribute to the formation of the structural elements of the ice. Fat remains in the form of spherical, emulsified droplets or is converted into a partially crystalline structure. Water is transformed into ice crystals. Air is churned into small bubbles, and sugars and stabilizers are frozen in the nonfrozen phase of the serum [1]. Identification of microstructures of food is important for dimensional regulation of identifiable components that constitute the food. Especially in products such as ice cream, from a technological point of view, the microstructure is important to yield products with the desired textural and sensory properties. Figure 3 shows the microstructure of ice cream subjected to two pasteurization methods: traditional and ultrasound. Larger voids are observed in the images of samples PP5, PP6, and PP7, which were subjected to traditional pasteurization, indicating a higher overrun compared with the samplessubjected to ultrasound pasteurization. A compact structure is observed in the images of samples UP5, UP6, and UP7, which were subjected to ultrasound pasteurization, indicating a lower overrun. The ultrasound treatment is found to promote a reduction in the size of fat globules due to cavitation onto nanoparticles. In addition, finer spaces formed by the formation of the fine crystalline structure of the ice can be observed. The skimmed milk to the ultrasound treatment at 20 kHz for up to 60 min reduced the size of fat globules to about 10 nm [48]. [PERSON] et al.