## 3 Results and Discussion
### Total Polyphenol Content (TPC), Flavonoids and Condensed Tannins  
During the storage period, total polyphenol content followed an increasing evolution for all irradiated and control samples compared to the initial analysis (D\({}_{0}\)) (Table 2). Total polyphenols in irradiated samples increased more than the control, regardless of dose, during the first month of storage. This increase is highly significant for the three doses but more considerable for the highest one. Indeed, this content reached 0.537 g kg\({}^{-1}\) at the first month versus 0.288 g kg\({}^{-1}\) in the control. This is similar to the result obtained by [PERSON] and [PERSON] [35], who observed that TPC content in soybean samples rapidly increased as a result of UV-C exposure. UV-C also induced the accumulation of phenolic compounds in tomatoes [36; 37] and in grapes [38]. The increase in our case was followed by a decrease compared to the first month, but the levels remained higher than that of control for the remainder of the storage period. In comparison, [PERSON] et al. [39] found a diminution of phenolic compounds after UV-C treatment of mushroom which led to its browning by, most likely, oxidation of these compounds. [PERSON] et al. [40] reported that no change was observed in the phenolic content of blueberry samples irradiated at 2 and 4 kJ m\({}^{-2}\). The nature of phenols, the constitution and the physiology of each plant, in addition to storage conditions, may be the source of this diversity of results. The results illustrated in Table 2 show a significant increase, regardless of dose, in flavonoid contents of irradiated samples in the last two months of storage compared to values detected in the first three months, where there is no significant difference in flavonoid concentration between control and treated samples. This result is somewhat similar to those obtained by some researchers. According to [PERSON] et al. [41],  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Storage Period** & **Irradiation Doses** & **TP Content** & **Flavonoids** & **Tannins Content** \\
**(Months)** & **(kJ m\({}^{-2}\))** & **(g kg\({}^{-1}\))** & **Content (g kg\({}^{-1}\))** & **(g kg\({}^{-1}\))** \\ \hline
0 & - & 0.274 \(\pm\) 0.014 & 0.034 \(\pm\) 0.003 & 0.109 \(\pm\) 0.010 \\ \hline  & 0 & 0.288 \(\pm\) 0.027 a & 0.035 \(\pm\) 0.003 & 0.131 \(\pm\) 0.003 a \\
1 & 1 & 0.469 \(\pm\) 0.007 b & 0.038 \(\pm\) 0.004 & 0.299 \(\pm\) 0.003 b \\  & 3 & 0.453 \(\pm\) 0.009 b & 0.046 \(\pm\) 0.003 & 0.370 \(\pm\) 0.002 c \\  & 6 & 0.537 \(\pm\) 0.014 c & 0.039 \(\pm\) 0.002 & 0.283 \(\pm\) 0.020 b \\ \hline  & 0 & 0.274 \(\pm\) 0.02  
an accumulation of phenols and total flavonoids is noted during storage, following the application of 2.46 and 4.93 kJ m\({}^{-2}\) doses on _Mangifera indica_. In addition, exposure to a dose of 4.1 kJ m\({}^{-2}\) induced an overproduction of total phenols in _Fragaria \(\times\) ananassa Duch._ Cv. _Toyonoka_[42]. Flavonoids could play a protective role against pathogens and environmental stress, due, for example, to drought or ultraviolet radiation, as has been noted in several works. Generally, the increase in phenol levels following UV-C exposure is associated with stimulation of the expression of the phenylalanine ammonia lyase gene; this was also confirmed by [PERSON] and collaborators [38] when studying the effect of UV-C treatment on table grape in addition to other genes involved in the phenylpropanol pathway. However, the application of increasing UV-C doses of 3.2, 9.6 and 19.2 kJ m\({}^{-2}\) on _Lycopersicom esculentum_ cv. Durita increased total phenol levels during storage [43]. In contrast, [PERSON] et al. [23] observed a decrease in total phenol and flavonoid content in _Brassica oleracea_ L var. Italica, cv. Cicco following exposure to UV-C doses of 4, 7, 10 and 14 kJ m\({}^{-2}\).