## 3 Results and Discussion
### Changes in Chemical Composition Before and after Storage in CA
#### 3.1.2 Evaluation of Soluble Solids and Titratable Acidity  
The content of soluble solids and titratable acidity are some of the most important indicators of apple quality [27]. The acidity of apples is an important indicator of organoleptic properties that influence the perception of fruit taste. The sour taste of apples depends on the complex of organic acids (malic, citric, tartaric, etc.) [3], while the sweet taste of apples depends on the content of soluble solids [33]. The evaluation of the content of soluble solids and the qualitative indicators of titratable acidity allow for assessing the quality and commercial value of apples. Our study showed that the content of soluble solids in apple samples before storage varied from 12.40 to 14.00%, and titratable acidity ranged from 0.24 to 0.61% (Table 4). The highest content of soluble solids (14.00%) was found in apple samples of the 'Rubin' cultivar, and the highest titratable acidity (0.61%) was found in apple samples of 'Cortled' and 'Noris' cultivars (Table 4). [PERSON] et al. pointed out that the content of soluble solids in the samples of apples grown in Italy, the Netherlands, and Poland was 12.08%, 12.11%, and 14.69 to 14.74%, respectively [44]. In a study by [PERSON] and [PERSON], the highest titratable acidity of 0.56% was found in apple samples of 'Mondial Gala' and 'Royal Gala' cultivars [40]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & **Before Storage** & **I** & **II** & **III** & **IV** & **V** & **VI** & **VII** & **VIII** \\ \hline Cultivar & & & & mg/100 g & & & & & \\ ‘Alva’ & 7.20 & 6.40 & 6.40 & 6.00 & 6.40 & 6.00 & 6.00 & 6.40 & 6.40 \\ ‘Auksis’ & 7.20 & 6.40 & 6.00 & 6.00 & 6.40 & 6.00 & 5.60 & 6.00 & 6.00 \\ ‘Connel Red’ & 8.00 & 7.20 & 7.20 & 6.00 & 5.60 & 6.40 & 6.40 & 6.40 & 6.40 \\ ‘Cortled’ & 7.20 & 6.00 & 6.00 & 5.60 & 6.00 & 6.40 & 6.00 & 6.40 & 6.00 \\ ‘Ligol’ & 7.20 & 6.40 & 6.40 & 6.40 & 6.80 & 6.40 & 6.40 & 6.00 & 6.80 \\ ‘Lodel’ & 8.00 & 6.40 & 7.20 & 6.40 & 7.20 & 6.40 & 6.40 & 6.80 & 6.40 \\ ‘Noris’ & 8.00 & 5.60 & 6.00 & 6.00 & 6.00 & 5.60 & 6.40 & 6.80 & 6.40 \\ ‘Rubin’ & 7.20 & 6.40 & 6.00 & 6.00 & 6.00 & 6.00 & 6.40 & 6.00 & 6.40 \\ ‘Sampion’ & 8.80 & 8.00 & 8.00 & 8.00 & 6.40 & 7.20 & 7.20 & 7.20 & 8.00 \\ ‘Spartan’ & 8.00 & 6.80 & 6.40 & 6.40 & 6.80 & 6.00 & 6.40 & 7.20 \\ \hline \end{tabular}
\end{table} 
Table 3: Variability of the quantitative composition of ascorbic acid in apple samples before and after storage in CA. An upward trend in the content of soluble solids was observed in apple samples stored in the conditions of chambers I-VIII (Table 4). The greatest increase in the content of soluble solids was observed in apple samples of 'Lodel' and 'Rubin' cultivars stored in chamber II conditions (from 13.20 to 16.80% and from 14.00 to 17.60%, respectively) (Table 4). [PERSON] et al., in their study, found that the content of soluble solids in apple samples during storage increased from 9.93 to 13.08%, which confirms the results of our study [45]. [PERSON] and [PERSON] determined that the amount of soluble solids increased during apple storage because starch or other polysaccharides in cell walls were hydrolyzed as the amount of water in the cells decreased [40]. Scientific literature provides data on the decreasing trend of the content of soluble solids during storage of fruit samples. The downward trend can be explained by the biosynthesis of anthocyanins in apple skin. During anthocyanin biosynthesis, sugars in apples are used in the anthocyanin glycosylation processes, which results in a decrease in the total content of soluble solids [46]. A decreasing trend of titratable acidity was observed in apple samples stored in chambers I to VIII (Table 4). The greatest decrease in titratable acidity (from 0.61 to 0.40%) was observed in apple samples of the 'Cortled' cultivar stored in chamber II conditions (Table 4). Data from scientific literature indicating that the titratable acidity in apple samples decreased during storage and varied from 0.69 to 0.37% confirm the results of our study [40].