## 3 Results and Discussion
### Antioxidant Activity (AA)  
Two tests were conducted to determine the antioxidant properties of the apple snacks, DPPH and ABTS radical scavenging assays. The antioxidant activity values and their bioaccessibility rates in the fresh and dried samples are shown in Figure 4.  
According to the DPPH radical scavenging inhibition assay, fresh apple exhibited a higher value of antioxidant ability with 83.31%. In the dried apples it was demonstrated in the order OD65\({}^{\circ}\) > SD > OD85\({}^{\circ}\) > CC > CF (\(p\) < 0.00001) (Tables S25 and S26). [PERSON] [19] obtained similar results in solar-dried apples of the Amasya and Starking varieties, where high AA values were registered, comparing five cultivars grown in the same location and revealing the differences between peel and pulp in the fresh, oven-dried and solar-dried samples.  
Based on this evaluation it was found that the drying process resulted in the degradation of antioxidants in the apple, which is in agreement with the reports of [PERSON] et al. [73] and [PERSON] et al. [20]. The reduction in AA registered in OD85\({}^{\circ}\), compared with OD65\({}^{\circ}\) and SD, is not significant but can be associated with terminal degradation related to temperature. The results may suggest that CC and CF were dried at high temperature, as the AA value is the lowest compared with the other samples. However, it could also be related to the presence or absence of the peel [19; 47; 74], and in the case of commercial snacks, we do not have such clear information.  
\begin{table}
\begin{tabular}{c c} \hline
**Sample** & **Acrylamide Content (\(\upmu\)g/kg d.m.)** \\ \hline fresh & n.d. \\ \hline SD & n.d. \\ \hline OD65\({}^{\circ}\) & 25.4 \(\pm\) 12.7\({}^{\text{b}}\) \\ \hline OD85\({}^{\circ}\) & n.d. \\ \hline CC & 147.2 \(\pm\) 57.3 \({}^{\text{a}}\) \\ \hline CF & 98.7 \(\pm\) 39.4 \({}^{\text{a,b}}\) \\ \hline \end{tabular} Data are expressed as mean \(\pm\) standard deviation (n = 3). Values with different lowercase letters are significantly different (\(p\) < 0.05) (Tables S23 and S24).  
\end{table}
Table 4: Acrylamide content of fresh apple, samples dried with different methods (SD—solar; OD65\({}^{\circ}\)—oven at 65\({}^{\circ}\); OD85\({}^{\circ}\)—oven at 85\({}^{\circ}\)) and commercial samples (CC—commercial while label; CF—commercial label).  
For the ABTS assay, the samples had similar behavior to the DPPH analysis. The highest scavenging ability shows the same trend of fresh apple (40.33 mmol Trolox/g d.m.), followed by, in decreasing order, SD > OD65\({}^{\circ}\) > OD85\({}^{\circ}\) > CC > CF (\(p\) < 0.000020) (Tables S27 and S28).  
[PERSON] et al. [75] and [PERSON] and [PERSON] [56] found different results from ours in their apple drying studies, where antioxidant activity increased with temperature. On the contrary, [PERSON] et al. [20] in apple peel dehydration, [PERSON] and [PERSON] [16] in red-fleshed apple and [PERSON] and [PERSON] [76] in Jamhbul and wood apple had results similar to ours, where antioxidant activity decreased with temperature. Once again, the utilization of the whole apple could interfere with the obtained results. Many authors compare the analyses of TPC and AA, and their increasing correlation has been reported during food dehydration [20; 49; 51]. However, in our study this relatioship is not obvious. It was found that the antioxidant ability of samples treated at different temperatures had no positive correlation with phenolic content, especially in SD samples, which might be because the free radical scavenging ability of the apple after drying was not only related to the total content of phenolic compounds, but also might be related to the non-heat-sensitive antioxidant components and the concentration of sugars. Other reasons could include the varieties studied and the means of preparation of the extracts, which are different among studies [77; 78].