## 3 Results and Discussion
### Changes in Moisture, Total Sugar and Protein Contents  
In order to note the irradiation effect on water retention capacity, the variation in humidity rate within the fruit was measured, as it is a quality criterion of dates. The changes in water content of Deglet-Nour samples were obtained during storage period (Figure 2). Water content decreased in all treated samples and the control. Expressed in percentage, it ranged from 25.13 in the first month to 12.42% at the end of the storage period. Some authors have explained the decrease in moisture by evaporation of date water following the destruction of the cellulose walls and the pecto-cellulosic substances [16], probably during postharvest handling. The decrease in moisture content is less pronounced in the case of irradiated samples when referring to control, especially for doses 1 and 6 kJ m\({}^{-2}\) during the first two months of storage, which can be explained by water retention and reduction in fruit sweating after irradiation. After one month of storage, the decreases were 2.52%, 10% and 5.82%, corresponding to doses of 1, 3 and 6 kJ m\({}^{-2}\), respectively, versus 11.28% in the control. Doses 1 and 6 kJ\(\cdot\)m\({}^{-2}\) significantly slowed water loss of samples until the second month of storage, with 17.68% and 16.02% of loss compared to control (31.45%). It is certain that dehydrated Deglet-Nour loses its market value, as it normally  
\begin{table}
\begin{tabular}{c c c} \hline
**Storage Period** & **Irradiation Doses** & **Carotenoid Content** \\
**(Months)** & **(k) m\({}^{-2}\))** & **(mg kg\({}^{-1}\))** \\ \hline
0 & - & 3.46 \(\pm\) 0.33 \\ \hline  & 0 & 3.41 \(\pm\) 0.22 \\
1 & 1 & 3.49 \(\pm\) 0.20 \\  & 3 & 3.47 \(\pm\) 0.10 \\  & 6 & 3.62 \(\pm\) 0.07 \\ \hline  & 0 & 3.45 \(\pm\) 0.12  \\
2 & 1 & 4.17 \(\pm\) 0.07  \\
2 & 3 & 3.51 \(\pm\) 0.21  \\  & 6 & 4.02 \(\pm\) 0.06  \\ \hline  & 0 & 3.35 \(\pm\) 0.16 \\
3 & 1 & 3.58 \(\pm\) 0.02 \\  & 3 & 3.48 \(\pm\) 0.25 \\  & 6 & 3.77 \(\pm\) 0.17 \\ \hline  & 0 & 3.33 \(\pm\) 0.25 \\
4 & 1 & 3.44 \(\pm\) 0.25 \\  & 3 & 3.00 \(\pm\) 0.17 \\  & 6 & 3.56 \(\pm\) 0.13 \\has a soft to semi-soft consistency, and the slowing down of the water loss by this treatment participates in preserving the fruit quality. Radiation's effect on water content found in this study is in perfect agreement with results obtained by [PERSON] et al. [17], who noted that water content was more important in the irradiated samples with a decrease rate between 174 and 130 g kg\({}^{-1}\) of fresh weight for the same date variety. The evolution of sugar content obtained for control and irradiated samples of the Deglet-Nour date, during five months of storage, is shown in Figure 2. The decrease in total sugars was slight but more pronounced in the case of the control until the second month of storage, where the difference appears significant. The diminution in total sugar content can be explained by the consumption of sugars as respiratory substrates [4] to ensure the energy supply necessary for the metabolism of the date fruit during postharvest storage. Until the second month, the slowing down of sugar consumption was significantly favored in the samples irradiated at 1 and 6 kJ m\({}^{-2}\), which was marked by decreases of 4.98% and 4.57% versus 8.96% in the control. The obtained results of total sugar contents are in agreement with those of [PERSON] and collaborators [18] on broccoli and those of [PERSON] et al. [19] on strawberry. In fact, they found that the total sugar content decreased slightly immediately after treatment with 4.1 kJ m\({}^{-2}\) of UV-C, and also during storage when referring to control group. During the first month of storage, the difference between total sugar content of irradiated samples and that of control does not appear to be significant, probably because water loss was greater in control and thus respiration lower, since an increase in fruit breathing rates has been observed with higher moisture content [4,20].