## 3 Results and Discussion
### Determination of Antioxidative Properties by DPPH and FRAP Method  
Considering the different mechanisms of antioxidant action, fat-free dairy desserts with different dried vegetables were evaluated using DPPH and FRAP. The results of the measurements are presented in Figure 4 (DPPH method) and Figure 5 (FRAP method). Both methods are based on a similar mechanism of action, i.e., transfer an electron from an antioxidant to an oxidant. Using the DPPH method, the ability of the antioxidants to donate hydrogen radicals or an electron to the stable DPPH free radical was measured. All tested products could reduce radical DPPH into DPPH-H. Along with the amount of added powder, an increase in the value (\(\mu\)mol Trolox/g of dessert) was noted (beetroot, championon, and onion addition) (Figure 4). The value increase in samples with dried carrots was insignificant compared to other products (\(p>0.05\)). The highest measurements were observed in dairy desserts with beetroot powder (0.16-1.14 \(\mu\)mol Trolox/g of dessert) and the lowest in the samples with carrot powder addition (0.082-0.67 \(\mu\)mol Trolox/g of dessert). The DPPH value of the dessert prepared without adding dried vegetable powder (9% WPC80) was 0.27 \(\pm\) 0.25 \(\mu\)mol Trolox/g [22]. It suggests that a 1% addition of vegetables may not be sufficient to improve the capacity to neutralize DPPP radicals in any of the vegetable  
Figure 4: Effect of different amounts of dried vegetable powders on fat-free dairy desserts’ antioxidative properties (DPPH). Letters (a–i) indicate significant differences at \(p<0.05\) ([PERSON]’s HSD test). enriched dessert. A 3% additions significantly improved antioxidant potential in the case of beetroot and button mushroom (not onion and carrot, though). When 5% addition was applied, every dessert (except carrot-enriched) had increased antioxidant capacity in the following order: beetroot > championgnon > onion. [PERSON] et al. (2014) tested yogurt fortified with dietary fiber. They added dried grape pomace (1-5%) and found that the higher amount of added fiber increased scavenging activity in the final product [36], which is consistent with our results. One of the criteriums connected with antioxidative capacity is the ability of the product to reduce ferric ions [53]. The FRAP method was used to examine this feature of the tested products. The examination of the antioxidative properties of prepared fat-free dairy desserts enriched with dried vegetable powders was presented in Figure 5. In each tested product, the values of reducing ferric ions of individual samples increased along with the amount of added powder. Similarly to the results with the DPPH method, in the samples with dried carrots, the increase in the abovementioned value was insignificant compared to other products (\(p>\) 0.05). The highest values were observed in the dessert with 5% beetroot powder (2.66 umol Trolox/g of dessert). In research from 2020 regarding fat-free desserts, it was concluded that adding whey proteins to the final product influenced the antioxidative capacity of the desserts, among others, due to the higher content of lactoferrin [22]. As confirmed by the presented results, the addition of dried vegetable powders increased the value of the antioxidant activity proportionally to the vegetable content. Moreover, antioxidant capacity measured by the FRAP method was increased, compared to the dessert prepared without adding vegetable powders (9% WPC80--0.4 \(\pm\) 0.06 umol Trolox/g of dessert) [22]. The only exception was the dessert containing 1% of carrot, in which antioxidant properties were not improved. This study is consistent with the antioxidant ranking of different vegetables proposed by [PERSON] and [PERSON] [54]. According to these authors, beetroot and mushrooms can be regarded as strong antioxidants, while onion and carrot belong correspondingly to the group of medium and weak antioxidants.