## 4 Discussion  
The quality attributes of whole spears and tips of green asparagus include appearance, color, and texture. According to the EU Commission [36], the color of green asparagus must be green for at least 80% of the length. The tip must be compact, and the spear slightly curved (for the best classification). For consumers, texture is important as well as aroma and flavor. The latter is determined by sugars, organic acids, and phenolic compounds such as rutin and hydroxycinnamic acids [37]. Among phenolic acids detected in the asparagus cell wall, the most representative are \(p\)-coumaric and ferulic acids. In our study, the most representative hydroxycinnamic acid was caffeic acid, followed by ferulic acid, but no trace of \(p\)-coumaric acid was detected. This difference could be attributed to differences in cultivars and agronomic practices [11]. Regarding flavonoids, quercetin exerts its antioxidative effects through multiple mechanisms. Firstly, it acts as a scavenger of free radicals, neutralizing them and preventing them from causing damage to cell membranes. Additionally, quercetin enhances the activity of superoxide dismutase, catalase, and glutathione peroxidase, which are endogenous antioxidant enzymes, and further contribute to the cellular defense against oxidative stress. The antioxidant effects of quercetin are due to its structural arrangement, which includes several hydroxyl groups attached to different positions on the benzene rings. Moreover, the conjugation of double bonds in the aromatic rings strengthens the antioxidant activity, creating a complex structure that plays a crucial role in quercetin's bioactivity and physiological effects. Rutin is a glycoside of quercetin, which is a compound made up of quercetin linked to a sugar called rutinose and has a lower antioxidant activity in respect to quercetin [38]. The concentration of rutin in asparagus depends on the variety chosen; moreover, environmental conditions have a significant impact, and the positive effect of sunlight on accumulation, specifically on rutin, has been documented by several authors [11,39]. UV-C could cause an increase in the concentration of bioactive compounds, and as indicated in the present work, the positive effects depended on the dose applied. For TPC, TFC, ABTS, and DPPH, a general increase was observed, but not with all doses. Similarly, it was observed for phenolic acids and flavonoids, including rutin and quercetin,  
Figure 4: Principal component analysis (PCA) score plot (**a**) shows the distribution of UV-C treatments and storage time. PCA loading plot (**b**) shows the distribution of the analyzed variables. whose content increased at a low dose (UV-C2). There are conflicting opinions in the literature on this topic. Some authors have indicated that high doses of UV-C decrease antioxidants, presumably due to damage to the cell membrane [40]. This would lead to a reduction in antioxidants for their activity in contrast to the oxidative stress. However, other authors have found an increase in antioxidants in fresh-cut mangoes, spinach, tomato, and blueberries with moderate doses of UV-C, like our UV-C doses [41; 42; 43]. In our opinion, the question of why only some phenolics and flavonoids showed an increase after UV-C treatments is due to their specific involvement in quenching reactive oxygen species (ROS) [38]. The increase in quercetin observed after UV-C treatment can be explained by those mechanisms in which quercetin is involved, firstly as a scavenger of ROS and after as an enhancer of endogenous enzymes, as indicated by the increase in ABTS. Indeed, ROS are produced after UV-C application because they cause direct damage to the cell membrane. Consequently, the most reactive compounds are increased, as observed in the present study for quercetin, and consequently, the activation of endogenous antioxidant enzymes, which in turn determines the increase in ABTS.