# Antioxidant and Potentially Anti-Inflammatory Properties in Pasta Fortified with Onion Skin
## 3 Results and Discussion
### Antioxidant Activity
Therefore, we also determined the content and pro-health activity of pastas fortified with onion skin powder after cooking. Some studies suggest that the presence of oxygen, water, and heat treatment during food processing may decrease the level of certain sensitive phenolic antioxidants by its oxidative degradation or by the formation of compounds having pro-oxidant action [43; 48; 51]. In our study, this effect seems to be marginal, and higher concentrations of phenolic compounds and an increase in antioxidant potential could be explained by several mechanisms. Thus, there are  
Figure 2: Antioxidant activity of extracts from uncooked and cooked pastas fortified with onion skin powder. P0—control pasta; P2.5-7.5 pastas fortified with 2.5–7.5% (m/m) of onion skin powder; (a) ABTS\({}^{+}\)—radical-scavenging ability against ABTS\({}^{+}\); (b) RP—reducing power; (c) CHP—chelating power. Different letters indicate significant difference (\(p<0.05\)). reports suggesting that cooking may increase the phenolic content and the antioxidant properties. The proposed mechanisms are connected with disruption of cell wall components, resulting in the release of associated polyphenols. Additionally, heating may be associated with releasing the dietary fiber-bound phenolic compounds with high antioxidant activity [52]. In addition, [PERSON] at al. [53] suggested that pasta cooking may influence the antioxidant potential by influencing the content of phenolic compounds and/or by changing the ratio between free and bond forms of phenolics. High IC50 values indicate low antioxidant activity. The fortification of pastas with dry onion skin caused significant elevation of the anti-inflammatory potential of the samples (LOX inhibition). A linear relationship between the LOXI activity and the amount of OS added was observed. The highest increase of LOX inhibition by phenolic compounds occurring in extracts was observed in pastas enriched with 5 and 7.5% (m/m) of OS (the IC50 values were 0.25 and 0.19 mg DW/mL, respectively), with respect to the control (IC50 = 0.33 mg DW/mL). Cooking of pastas significantly increased the anti-inflammatory potential of the extracts. An increase in LOX inhibition was already observed in pasta with the lowest level of added onion skin (the IC50 values were below 0.07 mg DW/mL, with respect to the control IC50 = 0.13 mg DW/mL) (Figure 3). These qualities of pastas are due to the presence of dry onion skin with high anti-inflammatory potential (Table 1). Numerous studies confirmed that onion is the main source of dietary bioavailable quercetin derivatives with strong anti-inflammatory capacity [49]. Phenolic compounds are a part of the antioxidant system. Their activity depends on chemical structure. They function as free radical scavengers by donating hydrogen or electrons. It has been proven that the antioxidant potential of plant material usually correlates with the phenolic content [42]. The Pearson correlation coefficient between phenolic compounds, analyzed in this research, and ABTS radical scavenging activity of pastas fortified with onion skin powder is very strong (R\({}^{2}\) = 0.930 and 0.912 for PAC and Q, respectively), indicating significant contribution of phenolics to the overall antioxidant capacity of pastas (Table 2). A strong correlation between PAC and RP (0.808), as well as Q and RP (0.798), was also detected. A moderate correlation was observed for CHP and the analyzed compounds: 0.768 and 0.760, respectively, for PAC and Q. Similarly, in other research works, the correlation between phenolic content and antioxidant capacity in _Allium_ species was observed [58]. A strong correlation (0.93 and 0.97) between total phenolic compounds and FRAP values was also reported in _Allium cepa_ cultivars [59]. Several authors also observed the strong correlation between total phenolics and antioxidant activity in wheat. Significant correlations between carotenoid content and DPPH scavenging activity in whole grain and the endosperm fraction were reported by [PERSON] and [PERSON] [60].