## 3 Results and Discussion
### Functional Properties  
GPP is a rich source of polyphenols, which are the most abundant antioxidants in the human diet with potential health benefits [53]. The antioxidant capacity of GPP-added cheese was investigated only for the cheeses mostly appreciated by the judges; for this reason, \(\text{EC}\text{h}_{15}94\) and \(\text{CC}\text{h}_{15}94\) were analyzed through ABTS \({}^{+}\) radical cation decolorization assay. Both cheeses were submitted to the in vitro gastro-intestinal digestion and the ability of reduction of the radical was evaluated from the different digestion steps (Table 5). Post-oral fraction of the control cheese showed reducing activity that did not significantly (\(p>0.05\)) vary after gastric digestion (0.202 \(\pm\) 0.012 umol TE/g). Milk components, mainly high molecular weight casein, are considered responsible for the antioxidant capacity of the dairy products [54]. Moreover, it was reported that pepsin digestion does not increase radical scavenging activity of purified casein [55]. After intestinal digestion, the antioxidant activity of control \(\text{CC}\text{h}_{15}94\) cheese was about 50% higher than that measured after gastric phase, possibly due to the antioxidant fat-soluble vitamins released in the bile salts micelles or to the amino acids with reducing ability [56; 57]. When GPP-added cheese (\(\text{EC}\text{h}_{15}94\)) was submitted to the in vitro digestion, the antioxidant potential of the post-oral fraction was not recorded different from that of the relevant fraction of control cheese (\(p>0.05\)), indicating that dilution and homogenization in simulated saliva fluid did not cause polyphenols release (Table 5). Interestingly, a net rise of the reducing activity (+41%) was measured in the samples after gastric digestion. As reported by [PERSON] et al. [58],casein digestion by pepsin can affect the binding with incorporated polyphenols, resulting in their solubilization. The antioxidant activity of ECh\({}_{15}\)94 cheese increased also after the intestinal step (Table 5). Finally, all reducing components released through the digestion of both cheeses were solubilized in the bioaccessible fraction, i.e., the soluble fraction of the digesta available for absorption (Table 5). Overall, during the digestion process, with the exception of the oral phase, all fractions obtained from the digestion of the GPP containing cheese showed a much higher antioxidant capacity than GPP-free cheese. The reducing activity of the bioaccessible fraction of ECh\({}_{15}\)94 accounted for 175% of that measured in the corresponding fraction of CCh\({}_{15}\)94. Our results demonstrated the important contribution of the polyphenols of GPP to the antioxidant capacity of the cheese and highlighted the functional potential of the fortified product. Unregulated food lipids oxidation during digestion can lead to a postprandial oxidative stress condition, which negatively affects the human health [59]. Consequently, antioxidants contained in foods that are able to react with and detoxify Typoperoxyl radicals can be considered of interest to reduce the oxidative phenomena during digestion. Peroxyl radical scavenger activity of the bioaccessible fractions of the cheeses was compared against lipid oxidation of pig brain microsomes. When lipid peroxidation was induced in microsomes by AAPH in the absence of cheese, TBA-RS production started immediately reaching a maximum at 90 min incubation (Figure 4). Bioaccessible fraction from 0.1 g or 0.2 g of CCh\({}_{15}\)94 slightly slowed down TBA-RS formation in a dose-dependent manner. Interestingly, bioaccessible fraction from GPP-enriched cheese (ECH\({}_{15}\)94) caused a stronger dose-dependent inhibition of the lipid peroxidation, evidenced by the net delay in the initial TBA-RS formation and a higher reduction of TBA-RS production throughout the incubation period (Figure 5).