## 3 Results  
### Ascorbic Acid Content and Degree of Impregnation  
The raw materials for both cultivars were characterized by a similar ascorbic acid content, which was about 10 mg/100 g FW. Carrot contains low levels of ascorbic acid content. The determined content in this raw material was within the range reported in the literature: 1.6-14.0 mg/100 g FW [32; 33; 34]. The carrot cultivar had no significant impact on the efficiency of the impregnation process. In turn, the effect of the applied pressure on the ascorbic acid content and impregnation degree of the tissue was noted. Moreover, a strong correlation (r = 0.98) was also observed between the ascorbic acid content of the samples and the degree of impregnation. The use of lower pressure (5 kPa) resulted in significantly higher saturation than at 30 kPa. The increase in ACC at the lower pressure (5 kPa) was 33% and 43% for the Baltimore F1 and Komarno cultivars, respectively, compared to the AAC of the samples impregnated at 30 kPa. In the Baltimora F1 and Komarno cultivar, tissue saturation at 5 kPa was 9.7% and 11%, respectively (Figure 3b). [PERSON] et al. [2], impregnating carrot tissue with an isotonic solution, recorded a saturation of 16% at a slice thickness of 15 mm. On the other hand, in slices of the same thickness with an isotonic solution containing calcium lactate, they achieved a saturation level of 4.6% [10]. Thus, the degree of tissue saturation can be influenced by both the composition of the solution and cultivar.  
Many researchers indicated that an increase in the vacuum level contributes to better saturation of the tissue of plant raw materials [13; 35]. However, [PERSON] et al. [1], in studies on lowering the pH of carrots using vacuum impregnation at 50 mbar or 300 mbar, did not show that the pressure level had any significant effect on the degree of impregnation. The authors pointed to the high rigidity of the tissue, which may have limited the relaxation-deformation phenomenon in the tissue. [PERSON] et al. [2] found that the parenchyma in carrot root formed densely packed cells, which limits the possibility of filling those parts on the edge of the slice with external solution. However, the authors indicated that it was possible to saturate the central parts (the xylem and phloem). [PERSON] et al. [2] also stated that, in the case of carrots, saturation is mainly based on the external solution replacing the native liquids and gasses, with a smaller effect on the deformation-relaxation phenomenon. In this work, the level of vacuum pressure affected the degree of tissue impregnation. This is confirmed by the microtomography images, where, at a vacuum pressure of 30 kPa, saturation was only found in the central part of the slice; whereas, in the case of 5 kPa vacuum pressure, saturation (gray color) was found to cover a wider area (Figure 4). The  
Figure 3: Ascorbic acid content—AAC (**a**); impregnation degree—ID (**b**). Mean \(\pm\) standard deviation. Different letters above the bars show a significant difference at \(p<0.05\).  
different effects on carrot tissue impregnation may be related to cultivar diversity. Numerous publications have indicated significant differences in the content of structure-forming compounds and firmness related to different cultivars ([PERSON] et al., 2016; [PERSON] et al., 2016).  
The duration of the vacuum and relaxation stage may also influence impregnation efficiency. [PERSON] et al. (2016) and [PERSON] et al. (2016), applied a vacuum for 5, 10, or 15 min. In this research, the vacuum stage was twice as long. Extending the vacuum time may result in more effective removal of gasses and fluids from the intercellular space of the tissue. [PERSON] et al. (2016) observed a significant volume reduction in the tissue after compression in the mechanical test. Hence, they suggest that vacuum impregnation may result in the diffusion of calcium ions also into the parenchyma. A similar effect may occur in the case of ascorbic acid.