## 4 Conclusions  
We conducted a study to investigate the effects of different levels of salt (ranging from 0% to 6%) on the active compound content and the number of lactic acid bacteria in fermented yellow beetroot and its dried form. The study aimed to determine how salt addition affects selected properties of fermented yellow beetroot.  
We observed stable products after 4 and 8 days, which was attributed to the development of lactic acid bacteria, a decrease in the pH below 4, and an increase in the total acidity in the samples. We found that the addition of salt did not affect the stability of the products. However, it did affect the active ingredients in fermented and freeze-dried yellow beetroot.  
During fermentation, 35-49% of the salt entered the beetroot tissues. This means that higher salt additions in the sink result in more salt penetrating into the beetroot tissue, which can impact the amount of salt consumed in the human diet. In order to comply with EU recommendations to reduce Na\({}^{+}\) intake, it is advisable to use lower salt additions. However, our study found that the addition of 2% salt by manufacturers to yellow beetroot resulted in lower amounts of lactic acid bacteria.  
On the other hand, a 1% addition led to higher levels of active ingredients, such as polyphenols and pigments, and satisfactory amounts of bacteria, even after the freeze-drying process. The fermentation process had a significant effect on the color components, altering the visual perception of the tested beetroots. It resulted in an increase in the polyphenol and pigment contents due to the loosening of the tissue, particularly at higher salt concentrations.  
Figure 4: FTIR results for selected beetroot examples: (**a**) for 0% salt addition; (**b**) for 2% salt addition; (**c**) for 4 th day of fermentation; and (**d**) for 8 th day of fermentation.  
Yellow beetroot, with its high content of polyphenols, pigments and lactic acid bacteria, can be used as a healthy ingredient in a diet after undergoing a freeze-drying process.  
These research findings provide valuable insights into optimizing the salt content to preserve the lactic acid bacteria, nutrients, and desirable color characteristics of fermented yellow beetroot. This could potentially position yellow beetroot as a matrix for healthier and higher-quality fermented vegetable products, or as a new raw material for innovative research.  
Conceptualization, E.J.-T.; methodology, E.J.-T.; software, A.W. and E.J.-T.; validation, A.W. and E.J.-T.; formal analysis, A.W. and E.J.-T.; investigation, A.W.; data curation, A.W. and E.J.-T.; writing--original draft preparation, A.W. and E.J.-T.; writing--review and editing, A.W. and E.J.-T.; visualization, A.W. and E.J.-T.; supervision, E.J.-T. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Data availability statementData are available from the corresponding author.  
The research for this publication was carried out with the use of research equipment purchased as part of the \"Food and Nutrition Centre--modernisation of the WULS campus to create a Food and Nutrition Research and Development Centre (CZiZ)\" co-financed by the European Union from the European Regional Development Fund under the Regional Operational Programme of the Mazowieckiovodeship for 2014-2020 (Project No. RPMA.01.01.00-14-8276/17).  
The authors declare no conflicts of interest.