## 4 Conclusions  
The results presented in this paper confirm that vacuum impregnation is an effective technique to give semi-products, in the form of carrot slices, the features of a functional food, which could contribute to increasing daily intakes of vitamin C. The amount of ascorbic acid in the carrot tissue increased from 10 to 140 mg/100 g FW. The effectiveness of impregnation depends both on the pressure of the vacuum (lower is better) and on the composition and structure of the raw material.  
Taking into account the results presented in the literature, it can be stated that prolonged impregnation times lead to a more homogeneous impregnation of the tissue. Microcomputed tomography images revealed that samples processed at 5 kPa for 30 min are impregnated almost completely through (negligible porosity), and even the parenchyma cells are saturated with the solution.  
Vacuum impregnation may induce the de novo synthesis of phenolic compounds under conditions of physiological stress, which is usually also observed during other processing (e.g., cutting, peeling). The total amount of polyphenols increased in the impregnated samples of the Komarno cultivar (compared to raw) from 106 to 426 mg/100 g DM. Chlorogenic acid and ferulic acid derivatives were mainly responsible for this increase.  
Evaluating the influence of the impregnation conditions on the analyzed parameters, it can be concluded that impregnation at lower pressure (5 kPa) is more favorable due to the higher ascorbic acid content and higher degree of impregnation. Although the samples saturated at 5 kPa were characterized by a stronger color change, the difference to the raw material was relatively small (\(dE\) from 3.5 to 5.5). At the same time, these samples were characterized by a lower whiteness index. Regarding the carrot cultivar, there were no clear differences between the tested cultivars. Only in the case of ion leakage, and regarding the content of polyphenic compounds, were more favorable results observed for the Komarno variety. It was characterized by a lower ion leakage and a higher content of total polyphenols.  
More studies are needed to determine the stability of the incorporated compound (ascorbic acid) in the product during successive preservation operations, such as drying.  
Conceptualization, E.R.-K., R.B.-M., J.S. and D.M.; methodology, E.R.-K., R.B.-M., J.S., D.M. and B.G.; formal analysis, [PERSON]-K., D.M. and B.G.; investigation, [PERSON]-K., [PERSON]-M., J.S., D.M. and B.G.; resources, E.R.-K., T.S. and D.M.; data curation, D.M.; writing--original draft preparation, [PERSON]-K., [PERSON]-M., J.S., D.M., T.S. and A.K.; writing--review and editing, [PERSON]-K., [PERSON]-M., J.S., D.M., T.S. and A.K.; visualization, D.M. and B.G.; supervision, [PERSON]-K. and D.M.; project administration, E.R.-K. and D.M.; funding acquisition, D.M. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the National Science Centre of Poland as part of the SONATA framework, project: no. 2018/31/D/ST8/00627.  
Not applicable.  
Data Availability Statement: The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.