## 3 Results and Discussion
### The Microscopy Structure Analysis  
Not only are the small ice crystals pivotal, but also the smooth and creamy mouthfeel of ice cream. Hence, controlling the crystallization process and the size or distribution of ice crystals are factors that determine the desired product and prolong the shelf life [15; 32; 36]. First and foremost, in the presented research, the size of the ice crystals was analysed based on the value of the average diameter (D\({}_{A}\)) in Table 4. Moreover, the distribution of the obtained ice crystal structure was studied in accordance with distributions obtained from the image analysis, which were characterised by the values for the ice crystal equivalent diameter at 50% of the cumulative distribution (X\({}_{50}\)) (Figures 1-3). To estimate the progress of recrystallization, the samples of milk ice cream were examined after 24 h, 1 month, and 3 months of storage at \(-18\)\({}^{\circ}\)C.  
After 24 h of storage, it was noted that the average diameter (D\({}_{A}\)) ranged from 9.05 to 17.85 \(\upmu\)m (Table 4). The lowest diameter of crystals was observed for sample CU (without the addition of stabilizers and after the ultrasound treatment), while the highest one was for sample AH (with the acid hydrolyzates of \(\iota\)-carrageenan and after the traditional homogenization treatment). Overall, the size of the ice crystals in the obtained milk ice cream did not exceed 18 \(\upmu\)m. The ultrasound homogenization used contributed to the smaller ice crystals in milk ice cream, except for samples IU (sample with the \(\iota\)-carrageenan, and after the ultrasound homogenization treatment) and LU (sample with the enzymatic commercial lactase hydrolyzates of \(\iota\)-carrageenan and after the ultrasound homogenization treatment), in comparison with the traditional homogenization. The effect of ultrasound homogenization may be explained by the violent collapse of bubbles, which initiate the ice nucleation by creating local zones of high pressure in a very short time. Moreover, the force generated by the collapse of cavitation bubbles is able to fragment bigger ice crystals into smaller ones [15; 18; 37]. Therefore, ultrasound homogenization might be more effective in comparison with traditional homogenization. Based on the value of the ice crystal diameter at 50% of the cumulative distribution of the sample, the X\({}_{50}\) diameter ranged from 6 to 17 \(\upmu\)m (Figure 1). [PERSON] et al. [38], in whey ice cream with the addition of \(\iota\)-carrageenan as the main stabilizer, showed that the X\({}_{50}\) was around 15 \(\upmu\)m, which was similar to the presented research. The analysis of the structure of ice crystals after 1 month of storage, for milk ice cream, concludes that the effect of the recrystallization process was visible (Table 4). The average diameter of ice crystals ranged from 9.86 to 21.27 \(\upmu\)m. As mentioned in the description of results after 24 h of storage, sample CU (without the addition of stabilizers and after the ultrasound treatment) was characterized the smallest size of ice crystals. The highest progress of recrystallization was noticed for sample LH (sample with the enzymatic commercial lactase hydrolyzates of \(\iota\)-carrageenan, and after the ultrasound treatment), owing to the fact that the crystals grew almost 11 \(\upmu\)m. The most striking observation after this time in storage was the fact that the ultrasound treatment significantly contributed to the inhibition of the recrystallization process. In all of the prepared ice cream samples, the average diameter was smaller (from 9.86 to 18 \(\upmu\)m) than in the samples after mechanical homogenization (from 16.11 to 19.90) or only with the addition of stabilizers (15.57 to 21.27 \(\upmu\)m). Moreover, the value of ice crystal diameter at 50% of the cumulative distribution of the sample (X\({}_{50}\) diameter) was observed, extending from 9 to 20 \(\upmu\)m (Figure 2).