## 3 Results and Discussion
### The Influence of US or PEF Pretreatment on the Physical Properties (Color, Texture)
A trend can be observed that the use of higher energy consumption during PEF processing resulted in lower values of the a* parameter, which was associated with greater leaching of colored compounds, but these are not statistically significant changes. Strawberries subjected to sonication and then dehydrated were characterized by increasing values of the a* parameter along with the duration of the process. After 2 h of the process, similar values were found to the fresh ones. Fresh strawberries had a b* parameter of 23.9 \(\pm\) 8.0. Strawberries that received the PEF pretreatment followed by dehydration exhibited a notably lower value of the b* parameter. However, fruits subjected to sonication and then dehydrated for 2 h were characterized by b* parameter values similar to those of fresh material and material dehydrated for 2 h in sucrose. The \(\Delta\)E parameter determines the general color changes in strawberries after osmotic dehydration with or without a PEF and US pretreatment in relation to fresh fruit tissue. After dehydration, all fruits had values higher than 5, which means that the color changes were significant. After 2 h of dehydration, the material previously treated with a PEF was characterized by a lower parameter compared to the material subjected to the osmotic dehydration process alone, while strawberries treated with ultrasound had higher \(\Delta\)E values, but they were not statistically significant. [PERSON] et al. [60] found no significant differences in brightness (L*) between the fresh, PEF-pretreated, and osmotic dehydrated samples. Other studies have shown that a PEF can retain its color by releasing the intercellular content depending on the initial characteristics of the raw material, cell membrane permeability, and process conditions [60]. In turn, research by [PERSON] et al. [56] showed that the initial PEF treatment on the osmotic dehydrated of strawberries led to an increase in the L* value compared to the untreated strawberries. Research conducted by [PERSON] et al. [61] showed that the use of ultrasound before osmotic dehydration changes the color of plums due to water, which washes away solids and color. Figure 5 shows the test results regarding the change in texture during the osmotic dehydration process. To compress a fresh strawberry, the maximum force was equal to 0.2 \(\pm\) 0.05 N, while the work for compression was 0.4 \(\pm\) 0.1 mJ. Strawberries subjected to osmotic dehydration alone required less maximum compressive force over time, amounting to 0.14 \(\pm\) 0.06 N after 2 h. This means that the material has softened. Strawberries dehydrated after a PEF treatment were characterized by a low maximum force required for deformation compared to fresh and dehydrated fruit without pretreatment. In turn, in the material subjected to ultrasound, the maximum force needed to deform was higher and comparable to the material subjected to osmotic dehydration applied alone. Initially, the maximum force for the material subjected to sonication and dehydration was comparable to the raw material, and later it decreased, but still remained at a higher level than strawberries dehydrated using a PEF. A significant difference was found between the work needed to deform the raw material and the material osmotic dehydrated with using a PEF. In turn, the osmo-dehydrated material with the use of US was characterized by similar or slightly lower values of work necessary to deform compared to strawberries only dehydrated, but these changes were not statistically significant. The changes in the US-treated samples might be related to dissolution of pectin in cell walls as a consequence of ultrasound treatment, which results in reduced firmness [62]. By contrast, in case of the PEF treatment, research conduct by [PERSON] et al. [60] showed that 120 min of osmotic dehydration and a PEF treatment (35.1 kJ/kg) helped maintain the hardness of the pumpkin, not differing significantly from the texture of the fresh samples. However, [PERSON] et al.