## 2 Results and Discussion
### Volatiles of Citrus Fiber/Blackberry Gels
An investigation of sucrose and trehalose effects in amounts of 5%, 10% and 20% on benzaldehyde, benzyl alcohol and 2-hexenal in freeze-dried tart cherry puree showed that the concentrations of those volatiles depended on disaccharide types and their amounts. Additionally, a study on more complex matrices such as strawberry cream fillings (freeze-dried and evaporated) revealed that the retention of strawberry volatiles depended on disaccharides type (sucrose or trehalose) and their amount (3%, 5% and 10%) as well as on the process conditions [18; 21]. In the previous studies dealing with the dependence of volatiles' amount on disaccharide percentages, no increase or decrease of volatiles' amount was detected as a rule [18; 21; 29]. Similar results were observed in our study, illustrating that the interactions between components play a very important role in the behavior of volatiles in the fruit matrix. Additionally, competition between components for binding sites needs to be accounted for, since it has been proven that this competition could be a significant factor in the retention of volatiles, especially when they are added as mixtures of compounds [18; 21; 32; 33]. Flavor profiles of products do not depend only on the amounts of volatile compounds but also on their odor threshold, therefore odor activity values (OAVs) were calculated to further elucidate the contribution of individual volatiles to the overall flavor. OAVs were calculated as ratios of volatile concentrations to thresholds [34]. A summary of OAVs of blackberry juice, citrus fiber and gels (after preparation and after storage) based on published odor thresholds is provided in Tables 4 and 5. In blackberry juice, there were 8 volatiles with OAV higher than 1. The extremely high OAVs (over 10) were observed for \(\gamma\)-ionone, \(\beta\)-ionone and \(\alpha\)-ionone (59.71, 25.80 and 21.83, respectively), which are described as berry flavor compounds and 2-decenal (28.5). Fourteen volatiles had OAVs over one in citrus fiber, with eight of them with extremely high OAVs. Especially high OAVs were found for 2-nonenal, D-limonene, 1-ocen-3-ol, octanal and \(\beta\)-ionone (143.5, 60.32, 50.28, 5.56 and 34.5, respectively). Comparing OAVs of gels, it was observed that 12 volatiles had values over 1, from which 7 volatiles had extremely high OAVs. 1-ocen-3-one had the highest OAV (over 6000). From the aldehyde group of volatiles, 2-nonenal (approximately 69 for trehalose gels and 80 for sucrose ones), octanal, 2-decenal (approximately 11 for trehalose gels and 19 for sucrose ones) and 2-ocenal (approximately 10 for trehalose gels and 13 for sucrose ones) were detected with high OAVs. D-limonene was the terpene with the highest OAV in gels (approximately 36.5 for trehalose gels and 50 for sucrose ones), followed by \(\gamma\)-ionone (approximately 36.5 for trehalose gels and 47 for sucrose ones) and \(\beta\)-ionone (approximately 26 for trehalose fillings and 34 for sucrose ones). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Volatiles**} & **OT** & \multicolumn{6}{c}{**OAVs**} \\ \cline{2-9}  & **(\(\mu\)g/kg)** & **BJ** & **F** & **10\%\_T** & **20\%\_T** & **10\%\_S** & **20\%\_S** \\ \hline \multicolumn{9}{c}{Alcohols} \\ \hline
2-ethylhexanol & 138 & 0.15 & 0.04 & 0.09 & 0.10 & 0.10 & 0.17 \\ \hline
1-ocen-3-ol & 1 & 0.00 & 50.28 & 0.00 & 0.00 & 0.00 & 0.00 \\ \hline \end{tabular}
\end{table} 
Table 4: Odor activity values (OAVs) of blackberry juice, citrus fiber and citrus fiber/blackberry gels after preparation.