## 2 Results and Discussion
### Volatiles of Citrus Fiber/Blackberry Gels
All alcohols and acids were determined in higher amounts in gels with sucrose. Aldehydes and ketones were the most stable volatiles during storage, but only hexanal was determined in higher amounts in gels with trehalose. Terpenes, linalool, nerol and \(\alpha\)-ionone were determined in higher amounts in gels with trehalose. The most abundant volatile after storage as well as after gel preparation was D-limonene, which was evaluated in the highest amount in sucrose-containing gels. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Volatiles** & **10\%\_T** & **20\%\_T** & **10\%\_S** & **20\%\_S** \\ \hline \multicolumn{5}{c}{Alcohols} \\ \hline
2-ethylhexanol & 12.09 \(\pm\) 0.07 b  & 9.02 \(\pm\) 0.09 d  & 9.93 \(\pm\) 0.11 c  & 13.73 \(\pm\) 0.16 a  \\ \hline benzyl alcohol & 11.94 \(\pm\) 0.06 c  & 9.10 \(\pm\) 0.10 d  & 12.93 \(\pm\) 0.11 b  & 17.07 \(\pm\) 0.08 a  \\ \hline
1-octanol & 14.65 \(\pm\) 0.22 c  & 13.89 \(\pm\) 0.10 d  & 20.48 \(\pm\) 0.07 b  & 25.15 \(\pm\) 0.37 a  \\ \hline phenethyl alcohol & 9.31 \(\pm\) 0.08 b  & 8.67 \(\pm\) 0.12 c  & 8.45 \(\pm\) 0.06 c  & 12.38 \(\pm\) 0.01 a  \\ \hline perilly alcohol & 2.32 \(\pm\) 0.06 c  & 2.85 \(\pm\) 0.06 b  & 2.58 \(\pm\) 0.15 b  & 4.57 \(\pm\) 0.02 a  \\ \hline \multicolumn{5}{c}{Acids} \\ \hline hexanoic acid & 28.46 \(\pm\) 1.88 a,b  & 26.40 \(\pm\) 0.12 b,c  & 29.81 \(\pm\) 1.84 a  & 24.79 \(\pm\) 1.35 c  \\ \hline nonanoic acid & 1.72 \(\pm\) 0.01 c  & 1.70 \(\pm\) 0.01 c  & 2.97 \(\pm\) 0.01 b  & 4.25 \(\pm\) 0.24 a  \\ \hline \multicolumn{5}{c}{Aldehydes and ketones} \\ \hline hexanal & 66.23 \(\pm\) 0.38 a  & 53.73 \(\pm\) 1.53 b  & 49.77 \(\pm\) 0.92 c  & 47.92 \(\pm\) 0.63 c  \\ \hline heptanal & - & - & 2.67 \(\pm\) 0.02 b  & 2.86 \(\pm\) 0.09 a  \\ \hline
2-heptrenal & 56.08 \(\pm\) 0.78 c  & 52.81 \(\pm\) 0.59 d  & 78.63 \(\pm\) 0.34 b  & 99.35 \(\pm\) 1.25 a  \\ \hline
1-octen-3-one & 40.52 \(\pm\) 0.10 b  & 37.29 \(\pm\) 0.02 c  & 29.12 \(\pm\) 0.09 d  & 61.88 \(\pm\) 1.53 a  \\ \hline
6-methyl-5-heptpen-2-one & 21.13 \(\pm\) 0.07 c  & 22.23 \(\pm\) 0.58 b  & 10.80 \(\pm\) 0.01 d  & 28.66 \(\pm\) 1.83 a  \\ \hline octanal & 16.01 \(\pm\) 0.10 c  & 21.25 \(\pm\) 0.64 b  & 28.19 \(\pm\) 0.21 a  & 29.06 \(\pm\) 1.93 a  \\ \hline
2-ocrenal & 21.98 \(\pm\) 0.34 c  & 16.44 \(\pm\) 0.12 d  & 30.67 \(\pm\) 0.45 b  & 44.68 \(\pm\) 1.76 a  \\ \hline
2-nonenal & 5.56 \(\pm\) 0.02 b  & 4.73 \(\pm\) 0.00 c  & 8.32 \(\pm\) 0.23 a  & 8.36 \(\pm\) 0.03 a  \\ \hline decanal & 5.33 \(\pm\) 0.01 d  & 6.18 \(\pm\) 0.10 c  & 7.49 \(\pm\) 0.07 b  & 9.56 \(\pm\) 0.12 a  \\ \hline
2,4-nonadienal & 3.71 \(\pm\) 0.10 c  & 5.84 \(\pm\) 0.22 b  & 5.44 \(\pm\) 0.04 b  & 6.65 \(\pm\) 0.03 a  \\ \hline
2-decenal & 3.47 \(\pm\) 0.10 c  & 3.39 \(\pm\) 0.02 c  & 5.98 \(\pm\) 0.16 b  & 7.86 \(\pm\) 0.14 a  \\ \hline ger In most previously published studies [15; 16; 17; 18; 19; 21; 28; 29; 30] conducted on the effect of trehalose on volatile compounds in different fruit matrices (strawberry cream fillings, orange jelly, strawberry puree, tart cherry puree, pear puree, tart cherry juice, pear cubes), a positive effect of trehalose on the overall retention of volatiles was observed, but in this study, we observed a different trend. In previous studies, it was noted that the positive effect of trehalose on volatiles depended on the properties of volatile compounds, and the matrix composition as well as on the conditions during processing and storage, which resulted in different interactions between components. Generally speaking, in this study, the positive effect of sucrose on volatile compounds was more pronounced than for trehalose. A study on the effect of 5% and 10% addition of sucrose or trehalose on the profile of tart cherry puree volatiles similarly revealed that both disaccharides type and the percentages added had an impact on tart cherry volatile compounds [29], but trehalose had a more positive effect than sucrose.