## 3 Results and Discussion
### The Microscopy Structure Analysis
In comparison with the results recorded after 24 h of storage, the recrystallization process could be proved based on parameter X\({}_{50}\). The research by [PERSON] et al. [19] also showed that using ultrasound (the frequency of 21.5 Hz) during freezing also contributed to the lower diameter of ice crystals for mango sorbent, of less than 10 \(\upmu\)m. Moreover, in research by [PERSON] and [PERSON] [18], the effect of ultrasound shortened the freezing time and at the same increased the overrun of ice cream, which improved the sensory of the final product. Additionally, [PERSON] et al. [39] proved that ultrasound effectively triggered ice nucleation and minimized the size of the ice crystals in mushrooms. On the other hand, [PERSON] et al. [40] indicated that the size of ice crystals was larger at higher nucleation temperatures and the sublimation time was reduced by almost 22 % compared with the control sample. Looking at the results after 3 months of storage (Table 4 and Figure 3), it is seen that the average diameter of ice crystals was less than 25 \(\upmu\)m. The highest ice crystals were noted for control sample C, while the smallest result was 14.74 \(\upmu\)m for the control sample after ultrasound treatment (CU). For all samples with the addition of stabilizers but without homogenization treatment, the size of the ice crystals ranged from 16.87 to 22.03 \(\upmu\)m. However, samples with the addition of stabilizers and after the traditional homogenization ranged from 15.14 to 21.74 \(\upmu\)m, while after the ultrasound treatment, they ranged from 14.86 to 18.4 \(\upmu\)m. Consequently, it was seen that the implementation of the homogenization process was necessary to obtain smaller ice crystals. However, the ultrasound was more beneficial than the traditional method. What should be highlighted is that the control sample (C) without stabilizers but after the ultrasound treatment achieved the smallest value for the average diameter at a level of 14.74 \(\upmu\)m. Additionally, the range of obtained ice crystals was close to 20 or less than this value, which may guarantee the desirable texture of ice cream, especially for consumers. Based on the value of the X\({}_{50}\) diameter, ranging from 12 to 21 \(\upmu\)m (Figure 3). Notable, to compare to results after 1 month of storage, the recrystallization process could be observed based on the parameter \(X_{50}\). [PERSON] et al. [41] proved that existing big crystals might be broken up into smaller ice crystals by high-intensity ultrasound. Maybe, in this case, such an ability of ultrasound was observed. Therefore, this increases the chances of effectiveness to inhibit the recrystallization process in milk ice cream. Taking into consideration the influence of the stabilizers used on the recrystallization process, it may be seen that in samples with \(\upiota\)-carrageenan (I) and its enzymatic hydrolyzates (B and L), the size of ice crystals was similar (around 18 \(\upmu\)m). For sample A, with the acid hydrolyzates of \(\upiota\)-carrageenan, the average diameter of ice crystals was higher (22.03 \(\upmu\)m). The reason may be the difference in the molecular structure of these stabilizers. In our previous study [13], it was proven that the mentioned enzymatic hydrolyzates of \(\upiota\)-carrageenan were more flexible based on FTIR (Fourier Transform Infrared Spectroscopy) analysis, and the vibration intensity of the -OH groups in the model solutions was seen in comparison with acid hydrolyzates. Overall, for the obtained hydrolyzates of \(\upiota\)-carrageenan, smaller vibrations were observed at 1213 and 914 cm\({}^{-1}\), which was connected with the decreasing number of sulphate groups and determined the better flexibility of hydrolyzates. Hence, the distinctive influence of stabilizers on the ice crystal structure was noted. Moreover, the average diameter in samples B and L had a similar value in comparison with sample A after 3 months of storage.