## 4 Discussion
Unlike other studies, and as already mentioned, the most representative hydroxycinnamic acid was caffeic acid, followed by ferulic acid [11]. Regarding flavonoids, the concentration of rutin in asparagus is also dependent on the variety chosen. In our control sample, rutin content was 6990 \(\mu\)g/g of dry weight, a concentration in agreement with [PERSON] et al. [7]. The authors found a concentration ranging between 259 and 763 mg/kg fresh weight of total flavonoids in 32 commercial green hybrids of asparagus; considering that approximately 90% of the weight of this vegetable is water, the concentration can be considered comparable. Storage time affected the content of all phenolic acids, flavonoids, and antioxidant activities, and as indicated in Table 2, antioxidant activity measured by ABTS showed no significant difference during the storage time, except for T2, where it reached the highest and most significant value. On the contrary, no variation over time was observed for the antioxidant activity measured by DPPH, which remained constant until T2. The observed behaviors were associated with variations in phenolic acids and flavonoids. Ferulic acid and kaempfer-3-O-rutinoside showed the highest content at T2 with respect to T0, with an increase of about 18% for both metabolites. Our results agree with those of [PERSON] et al. [15], who found that during postharvest storage, the amount of cell wall phenolics (mainly ferulic acid) increased significantly. Choosing the right dose of UV-C to apply is important to induce the hormetic effect, that is, the dose that induces the desired effects [44; 45]. Our study demonstrated that treatment with low doses of UV-C could be useful to limit the losses of phenolic compounds and flavonoids. The UV-C2 best prolonged the storability of rutin up to two weeks, while for quercetin, all the UV-C tested allowed the maintenance of the highest levels up to three weeks. In effect, our results indicated that the losses of rutin in the UV-C-treated samples were significantly lower than the control. This finding was in accord with [PERSON] et al. [41], who studied the effect of UV-C on the storability of antioxidant compounds on mangoes and found an increasing content after UV-C treatments. Postharvest treatment, with UV-C on asparagus and vegetables in general, could also have an effect in increasing the shelf life of the products, and decreasing ripening and senescence. Our findings indicated that hardness was significantly influenced by storage, while fiber content did not show significant variations over time, unlike protein content, which increased significantly by 7% from T0 to T2 and T3. Thus, the range of UV-C applied in this study did not affect the fiber content, which seemed not to be involved in hardening during storage. Therefore, this result indicated the prevalent involvement of phenolic cross-links in determining hardening during storage as previously found by [PERSON] et al. [15]. This study confirmed that protein content increased during storage [46], but also that the negative effect of the denaturation process caused by the highest UV-C doses can occur, as observed by [PERSON] et al. [47]. Regarding the interaction of UV-C and storage time on the hardness, only the maximum dose of UV-C showed a positive effect on hardening, which tended to reduce up to T3. [PERSON] et al. [48] have found that the lowest UV-C doses were the best in preventing hardening, while higher doses did not cause appreciable changes. Our findings showed that the UV-C4 prevented the hardening for a longer period of time than the other doses, suggesting that it may represent the hormetic dose for hardening. Indeed, in the control sample, after the first week (T1), the cultivar Grande tested in this study showed significant hardening, which remained unchanged up to the last week of storage (T3). On the contrary, the application of UV-C4 exerted a positive effect on the hardness, which always remained the lowest for two weeks. A similar effect with low doses of UV-C was observed in red tomatoes [49].