## 2 Results and Discussion
### Phenolics, Antioxidant Activity and Color of Citrus Fiber/Blackberry Gels  
Total phenolics content and proanthocyanidins content of citrus fiber/blackberry gels are presented in Table 6. From the results, it can be seen that both parameters, type of disaccharides and their amounts, had an impact on total phenolics as well as proanthocyanidins. After preparation of gels, the highest amount of total phenolics was found in the gel prepared with 20% of trehalose (5.233 g/100 g) and the lowest in gel prepared with 10% of sucrose (4.652 g/100 g). Gels prepared with 20% of sucrose and 10% of trehalose had an equal amount of phenolics (4.94 g/100 g). Throughout the storage period, a decrease of total phenolics occurred. Gels prepared with 20% of trehalose (4.558 g/100 g) and 10% of sucrose (4.133 g/100 g) retained the trend that was obtained during preparation, i.e., these samples also had the highest and lowest total phenol contents, respectively. For the other two samples, a different trend was observed. The gel with 20% of sucrose had a slightly lower content of total phenolics (4.504 g/100 g) than the gel with 20% of trehalose, while the gel with 10% trehalose had a lower content than the previously mentioned samples (4.354 g/100 g). Results of the evaluation of proanthocyanidin contents revealed that both gels with trehalose had a higher amount of those compounds (156.85 and 140.46 mg/100 g) than gels with sucrose (129.78 and 120.33 mg/100 g). Additionally, it was evident that samples prepared with the higher disaccharides amount had the higher amount of proanthocyanidins. The highest proanthocyanidins content, after storage, remained in gels with trehalose, but there was no difference between samples prepared with 10% or 20% of this disaccharide (121 mg/100 g). However, in the case of sucrose, samples prepared with a higher amount had higher proanthocyanidins content. Our results are in agreement with other studies that showed similar results on the protection of phenolics, flavonoids and anthocyanins by disaccharides' addition under different conditions during processing and storage, and emphasized that trehalose had a higher protective effect [18; 20; 21; 22; 23; 24; 25; 26; 27; 30]. As was the case in our study, [PERSON] et al. [18] also showed that with the increase of trehalose addition (3%, 5% and 10%) to strawberry cream fillings (evaporated and freeze-dried), an increase of phenolics and anthocyanins occurred, and this trend was retained during storage. In the study dealing with freeze-dried tart cherry pure  
Figure 1: PCA analysis of citrus fiber/blackberry juice gels. influence of sucrose and trehalose in amounts of 5%, 10% and 20%, results showed that with the increase of disaccharides amounts, a decrease of total phenolics, flavonoids and anthocyanins occurred, but the positive effects on those phenolics were more pronounced when trehalose was used as an additive [23]. Antioxidant activities of citrus fiber/blackberry gels prepared with different disaccharides after preparation and storage are presented in Table 6. Antioxidant activities of gels were evaluated using DPPH, ABTS, FRAP and CUPRAC methods, and different results were obtained. Antioxidant activity evaluated by the DPPH method revealed that gels with higher amounts of disaccharides had higher antioxidant activities than gels with lower amounts. Comparing values, gels with 20% of sucrose had the highest antioxidant activity and gels with 10% had the lowest. During storage, antioxidant activity decreased and gels with trehalose had higher antioxidant activity than gels with sucrose. In addition, there was no difference in antioxidant activity between gels prepared with different amounts of disaccharides. Using the ABTS method, a different trend in antioxidant activity was observed. Gels with trehalose had higher antioxidant activities than gels with sucrose, and the impact of disaccharides' amount was not observed. In contrast to all other used methods, an increase of antioxidant activity occurred after storage.