## 3 Results and Discussion
### Chemical Properties of Beetroot Samples
#### 3.3.3 Thermal Properties  
Table 3 presents the findings from the thermogravimetric analysis (TGA) of freeze-dried yellow beetroot samples fermented with varying salt additions. Thermogravinetric analysis is an advantageous method for evaluating the thermal stability of a substance by monitoring its weight loss as the temperature increases. As a result, this technique allows for assessing different features of food products that undergo high-temperature processes, offering an understanding of phenomena such as drying, dehydration, and dehydroxylation [67; 68]. Table 3 provides data on the temperatures and weight losses during the thermal degradation phases. All the dried samples displayed 3 of 4 phases of thermal decomposition. Phase I (30-110 \({}^{\circ}\)C) leads to the dehydration of freeze-dried samples [67; 69], showing the least mass loss compared to dried material containing a small amount of water 0.63-5.5% (refer to Table 2). Phase II and III are related to the decomposition of carbohydrates, such as glucose (150-200 \({}^{\circ}\)C) and sucrose (170-212 \({}^{\circ}\)C), and the degradation of organic compounds, such as polysaccharides, like hemicellulose (temperatures of 220-315 \({}^{\circ}\)C), cellulose (250-450 \({}^{\circ}\)C) and lignin (320-450 \({}^{\circ}\)C) [70; 71] which are present in freeze-dried fermented beetroot tissue. Figure 3: Results of antioxidant tests for the beetroot samples: (**a**) total polyphenols after fermentation; (**b**) total polyphenols after fermentation and freeze-drying; (**c**) antioxidant activity after fermentation; (**d**) antioxidant activity after fermentation and freeze-drying; a, b, c...—mean a statistically significant difference in the selected % through the whole fermentation process (from 0 to 2M); A, B, C...—mean a statistically significant difference for the selected day analyzed for all the tested salt contents (for each series). \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{ \begin{tabular}{c} **Salit** \\ **Content (\%)** \\ \end{tabular}  **} & \multirow{2}{*}{ \begin{tabular}{c} **Top 1** \\ **Top2** \\ **Top2** \\ \end{tabular}  } & \multicolumn{2}{c}{**Step 2**} & \multicolumn{2}{c}{**Step 3**} & \multicolumn{2}{c}{**Step 4**} & \multicolumn{2}{c}{**Sum (\%)**} & \multicolumn{2}{c}{**Decomposition Temperature (\(\circ\) C)**} \\ \cline{2-11}  & & & **Top2** & **Mass Loss** & **Temp** & **Mass Loss** & **Temp** & **Mass Loss** & **Temp** & **Mass Loss** & **Temp** & **Mass Loss** \\  & & & **Range (\(\circ\) C)** & **Range (\(\circ\) C)** & **Range (\(\circ\) C)** & **Range (\(\circ\) C)** & **Range (\(\circ\) C)** & **Range (\(\circ\) C)** & **Range (\(\circ\) C)** & **Ratio (\(\circ\) C)** & **Ratio (\(\circ\) C)** & **Ratio (\(\circ\) C)** \\ \hline \hline \multirow{2}{*}{\ \begin{tabular}{c} Prebl. 0 \\ 0 \\ 1 \\ 2 \\ 3 \\ 4 \\ 5 \\ 6 \\ \end{tabular}  } & \multirow{2}{*}{
\begin{tabular}{c} 1.98 \\ 30-10.64 \\ 10-230 \\ 1.81 \\ 1. During the measurement, it can be observed that there is a similar mass loss in phases II and III (approximately 20-35%). This could be attributed to the reduction in the sugars, specifically glucose and sucrose, during the fermentation process. With that said, it can be summarized that in phase II, mono- and disaccharides were decomposed, while in phase III, the initial degradation of polysaccharides occurred. In phase IV, the degradation of lignocellulosic components also occurred, but the amount of loss was smaller than for II and III phase compounds. It can also said that higher salt addition resulted in lower mass loss in all the tested temperature ranges. The observed temperature values were similar independently of the salt addition or day of fermentation (Table 3). The analysis of the samples obtained after the storage process revealed different behavior during the TGA thermogravimetric analysis. Three phases were identified, in which the degradation of the sample components occurred.