## 3 Results and Discussion
### Changes in Moisture, Total Sugar and Protein Contents
Indeed, it was reported that Deglet-Nour fruit with 27% moisture had a respiration rate five times higher than that of fruit at 20-22% of moisture [21]. Slight decreases in Deglet-Nour sugar content do not alter its nutritional value, as it contains large amounts at the full mature stage Tamar, most of which are glucose and fructose. It is also interesting to report that the increase in total sugar was observed in UV-C-treated sweet oranges [22], and that supports our obtained results of irradiated samples when compared to control. Proteins belong to one of the most important classes of molecules present in all living organisms. They provide the essential functions of the cell. Variation in total protein content in control and irradiated samples of the Deglet-Nour date during storage are shown in Figure 2.  
Analysis of the results shows that there is an increase in the total protein levels during storage compared to the control. This increase in protein content is more marked in the case of the irradiated sample at 6 kJ m\({}^{-2}\) in the third month of storage. Indeed, samples of 3 and 6 kJ\(\cdot\)m\({}^{-2}\) gave 1.70 and 2.41 g\(\cdot\)kg\({}^{-1}\) versus 1.29 g kg\({}^{-1}\) of the control. The increase may be due to the activation of biosynthesis of enzymes involved in synthesis of defense molecules against stress caused by UV-C. Most likely, the increase is concomitant with the slowing down of protein degradation, in particular by inhibition of the action of proteases, which is associated with the ripening and senescence of fruit, as has been reported in many works [23]. Therefore, it appears that the degree of slowing of protein decomposition is higher in the irradiated samples than in the control. Other hypotheses cited by [PERSON] and [PERSON] [24] indicate that protein synthesis or protection against degradation can be linked to maintaining the activity of antioxidant enzymes. Furthermore, [PERSON] et al. and [PERSON] et al. [18,25] confirmed that the protein content of broccoli is increased after irradiation at 8 kJ m\({}^{-2}\) for 21 d of storage at 4 \({}^{\circ}\)C but at a rate of about 5.05 g kg\({}^{-1}\) of fresh weight, which is greater than our result (2.40 g kg\({}^{-1}\)), recalling that the date generally contains small amounts of proteins. Figure 2: Variations in water, total sugar and total protein contents of Deglet-Nour samples, during five months of storage at 10 \({}^{\circ}\)C. Vertical bars represent standard error (\(n=3\)), 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. Another study conducted by [PERSON] et al. [26] on strawberry reported that the group of fruit which was treated with UV-C was marked by a significant decrease in the levels of simple sugars, namely glucose, fructose and sucrose, but also in the levels of organic acids, especially those of citric and ascorbic acids, while a slight decrease was observed for in malic acid. The researchers also noted that the growth, physicochemical quality, firmness and moisture of UV-C-treated samples were preserved when compared to control. The concentrations of nine types of essential amino acids were preserved in coconut water samples which were irradiated by UV-C [27].