## 3 Results
### The Effect of Storage on the Sensory Quality of Very-Low-Sugar Apple Jams with Added SGs
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Color** (L*\(\text{a}\)*\(\text{b}\)*)} & \multicolumn{4}{c}{**Addition of SGs (\%) to Very-Low-Sugar (VL) Jams**} \\ \cline{2-5}  & **0** & **30** & **50** & **80** \\ \hline \multicolumn{5}{c}{Color of Apple Jams at the Beginning of Storage *} \\ \hline L* & 32.6 \(\pm\) 0.74 & 33.89 \(\pm\) 0.61 & 34.1 \(\pm\) 0.56 & 34.53 \(\pm\) 0.06 \\ \hline \(\Delta\)L & - & 1.29 & 1.5 & 1.93 \\ \hline a* & \(-\)0.39 \(\pm\) 0.02 & \(-\)0.41 \(\pm\) 0.19 & \(-\)0.44 \(\pm\) 0.36 & \(-\)0.48 \(\pm\) 0.01 \\ \hline \(\Delta\)a & - & \(-\)0.02 & \(-\)0.05 & \(-\)0.09 \\ \hline b* & 15.77 \(\pm\) 0.78 & 16.1 \(\pm\) 0.65 & 16.31 \(\pm\) 0.48 & 16.79 \(\pm\) 0.09 \\ \hline \(\Delta\)b & - & 0.33 & 0.54 & 1.02 \\ \hline C & 15.76 & 16.09 & 16.30 & 16.78 \\ \hline \(\Delta\)C & - & 0.33 & 0.54 & 1.02 \\ \hline (\(\Delta\)E) & - & 1.33 & 1.60 & 2.18 \\ \hline \multicolumn{5}{c}{Color change after 3 months of storage **} \\ \hline L* & 32.51 \(\pm\) 0.74 & 33.43 \(\pm\) 0.01 & 33.87 \(\pm\) 0.01 & 34.21 \(\pm\) 0.2 \\ \hline \(\Delta\)L & \(-\)0.09 & \(-\)0.46 & \(-\)0.23 & \(-\)0.32 \\ \hline a* & \(-\)0.05 \(\pm\) 0.02 & \(-\)0.38 \(\pm\) 0.02 & \(-\)0.43 \(\pm\) 0.01 & \(-\)0.44 \(\pm\) 0.02 \\ \hline \(\Delta\)a & 0.02 & 0.03 & 0.01 & 0.04 \\ \hline b* & 15.47 \(\pm\) 0.02 & 15.3 \(\pm\) 0.13 & 15.85 \(\pm\) 0.05 & 16.19 \(\pm\) 0.04 \\ \hline \(\Delta\)b & \(-\)0.3 & \(-\)0.8 & \(-\)0.46 & \(-\)0.18 \\ \hline C & 15.76 & 15.29 & 15.84 & 16.18 \\ \hline \(\Delta\)C & 0.3 & 0.8 & 0.46 & 0.18 \\ \hline (\(\Delta\)E) & 0.3 & 0.92 & 0.51 & 0.37 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Color assessment of very-low-sugar apple jams (VL) with added steviol glycosides (average value \(\pm\) SD). After storage, the color of all the jam samples darkened (the \(\Delta\)L value was negative), and the samples were characterized by a stronger red color compared to the jams assessed at the beginning of storage (negative \(\Delta\)a values); however, these changes were not significant. After storage, the yellow color of the jams also changed; the jams were more blue than yellow (negative \(\Delta\)b values). The Effect of Storage on the Physicochemical Parameters of Very-Low-Sugar Apple Jams with Added Steviol Glycos  
After preparation, the content of total soluble solids (%) in the jams was 45.5, and the substitution of sugar with steviol glycosides led to a statistically significant change in content, up to 39.0. The prepared jams contained 95% of raw materials (apples), and the extract of apples used to prepare the preserves was 16.3%. With the increase in steviol glycosides, a statistically significant (\(p\leq 0.05\)) decrease in the dry matter content and total extract was observed (Table 5). The very-low-sugar product with the 80% SG substitution had an extract similar to that of raw apple. The storage of the jams for 3 and 6 months did not cause significant changes in the dry matter (\(p>0.05\)), which may indicate that adding citric acid and pectin stabilizes the composition and limits some physicochemical changes. The vitamin C content in all the jams was not high, and there was no strong correlation between its content and the addition of steviol glycosides (r = 0.32). During jam storage, significant changes in vitamin C were found in the jams, with \(p\leq 0.05\) (Table 5), in the range from 29 to 75%, regardless of the jams' composition (addition of SGs and sugar). The total ash content in the evaluated apple jams was related to the level of SG substitution (r = 0.64, \(p<0.001\)) and the jam storage time (r = 0.66; \(p<0.05\)). After six months of storage, an increase in its content was observed, which may indicate more minor changes occurring in the jams due to, for example, a stabilizer such as citric acid. In all the jams, the pH was maintained in the range of 3.2-3.48. The addition of pectin and citric acid stabilized the pH of the jams.