## 3 Results and Discussion
### Anti-Free-Radical Activity and Ferric-Reducing Power  
The general reading of the results of the scavenging effect analysis of DPPH radical (Figure 4) showed an increased rate of DPPH scavenging from the fourth month in favor of samples irradiated at doses 0.3 and 0.6 J cm\({}^{-2}\). At the end of the first three months of storage, no significant distinction could be drawn between the antiradical effect of irradiated samples and that of the control, despite the apparent increase in the case of treated samples. The increase in antioxidant activity during the storage of dates is probably due to biosynthesis and accumulation of phenolic compounds that play a very important role in free radical scavenging. The combination of these results with those of the total polyphenol (PPT) assays revealed a very significant linear correlation between the anti-free-radical capacity of the extracts and their PPT content (R\({}^{2}\) = 0.80) from the third month of storage, which means that the antioxidant activity is most likely due to the phenol composition of Deglet-Nour extracts. Most of these compounds have antioxidant activities, due to the presence of many hydroxyls in their structures, which can react with free radicals. The results of [PERSON] et al. [43] on Citrus pomaces, as well as those of [PERSON] et al. and [PERSON] et al. [51; 52] on broccoli and [PERSON] et al. [53] on sweet pepper, revealed that the increase in antioxidant capacity could be linked to the elevation in total  
Figure 4: Changes in DPPH scavenging activity and iron-(III)-reducing power of the of Deglet-Nour samples during five months of storage at 10 \({}^{\circ}\)C. Vertical bars represent standard error (\(n\) = 3); a, b: different letters indicate a significant difference between the four samples at each storage period (\(p\) < 0.01), while the absence of the letters indicates the absence of difference. phenols within UV irradiated samples, which is similar to ours. The rates of ferric reduction using Deglet-Nour samples, expressed as absorbance in 700 nm, are mentioned in Figure 4.  
The analysis of the results makes it possible to observe a significant increase in absorbance of irradiated samples after one month of storage relative to the control. An increase in absorbance means an increase in the reducing power of tested extracts. The increase in iron (III) reductive activity in all samples compared to the initial (D\({}_{0}\)) analysis would be due to the concentration of antioxidant molecules in the extracts as a result of water loss that was much higher in the control samples. Linear correlation between ferric-reducing power and phenolic contents was medium (R\({}^{2}\) = 0.5), thus involving part of these compounds. Generally, the reducing power of date extracts is due to the presence of substances having an ideal structure for free radical scavenging: possessing free hydroxyl groups and acting as hydrogen donors. Similar results have been observed by [PERSON] et al. [41] on mango, [PERSON] et al. [40] on blueberries and [PERSON] et al. [38] on table grape, where the increase in PPT content led to increased antioxidant activity. In addition to phenolics, involvement of selenium can be established, as date fruit is a good source of this element, 2.4-4 mg kg\({}^{-1}\)[2]. Indeed, [PERSON] et al. [54] found that the increase in the level of selenium in green tea leads to an increase in its antioxidant activities FRAP and DPPH. Otherwise, implication of carotenoids in these reductive activities cannot be considered, especially since the correlation between carotenoid content and antioxidant activity rate is low (R\({}^{2}\) = 0.13; 0.01). Moreover, the exposition of lettuce to UV-C radiation can significantly decrease DPPH scavenging activity, but also helps this plant to adapt and increase its tolerance to salinity stress [50]. In general, and from research studies that realized fruits and vegetables using UV-C radiation, results are encouraging, since quality was altered but improved in in most cases.