## 3 Results and Discussion
### Antioxidant Properties  
Bioactive peptides and phenolic compounds released during digestion of the cheese are considered to be the components primarily responsible for its antioxidative properties [57; 58]. GPP is a very rich source of polyphenol compounds with potential health-promoting effects due to the compound's ability to counteract with body oxidative stress [59]. Contribution of GPP components to the reducing potential of the cheese was estimated while evaluating the antioxidant capacity of GPP-fortified primosale EPC94 compared to the unenriched cheese CPC94, which were found to be the most appreciated by the judges. To simulate the degradation of the matrix in a gastrointestinal environment, samples of both the cheeses were submitted to in vitro digestion and the Total Antioxidant Activity (TAA) in the different digestion phases was measured by the ABTS\({}^{\star\bullet}\) decolorization assay. As shown in Figure 5, although post-oral fractions of both the cheeses showed reducing activity not significantly different, simulated PG fraction of EPC94 had a TAA value (0.342 \(\pm\) 0.028 \(\mathrm{\SIUnitSymbolMicro mol\,TE/g}\)) higher (_p_ \(<\) 0.001) than that of the CPC94 cheese (0.234 \(\pm\) 0.019 \(\mathrm{\SIUnitSymbolMicro mol\,TE/g}\)). It is plausible that digestion of casein micelles by gastric pepsin has solubilized the incorporated polyphenols in GPP-enriched cheese, resulting in an increase of the reducing activity of the fraction [60]. After intestinal digestion, antioxidant activity of the fractions from both cheeses was about 50% higher than that measured in the relevant gastric digesta, possibly because of release of antioxidant fat-soluble vitamins or amino acids from the dairy matrix [61; 62]. Finally, reducing compounds appeared entirely portioned in the BF, i.e., the soluble fraction of the intestinal digesta available for the absorption, and antioxidant capacity of BF from GPP-enriched cheese (0.590 \(\pm\) 0.033 \(\mathrm{\SIUnitSymbolMicro mol\,TE/g}\)) were 60% higher than that of the unenriched cheese (0.371 \(\pm\) 0.029 \(\mathrm{\SIUnitSymbolMicro mol\,TE/g}\)) (Figure 5). The antioxidant potential of the bioaccesible fractions of the cheeses was also assessed utilizing an in vitro model of membrane lipid oxidation. Lipid oxidation was induced in bovine brain microsomes (2 mg protein/mL) by AAPH-derived peroxyl radicals (20 mM) and oxidized lipids were spectrophotometrically measured as TBARS. In these conditions, after 60 min incubation at 37 \({}^{\circ}\)C, an amount of 0.91 \(\pm\) 0.07 nmoles TBARS /mg protein was detected (control, Figure 6). When BF from 0.1 g or 0.2 g of CPC94 cheese was added to the microsomal preparation before AAPH, slightly lower amounts of TBARS were measured (0.82 \(\pm\) 0.06 and 0.75 \(\pm\) 0.05 nmoles/mg protein, respectively). Interestingly, in the presence of BF from 0.1 g or 0.2 g GPP-fortified primosale EPC94, much more marked dose-dependent inhibition of the lipid oxidation was evident (0.55 \(\pm\) 0.04 and 0.29 \(\pm\) 0.01 nmoles TBARS/mg protein, respectively) (Figure 6). \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \multirow{2}{*}{**Attributes**} & \multicolumn{6}{c}{**Trial**} & \multirow{2}{*}{**SEM**} & \multicolumn{2}{c}{_p_**-Value**} \\ \cline{2-2} \cline{5-10}  & & **CPC36** & **EPC36** & **CPC94** & **EPC94** & **CPC169** & **EPC169** & **CPC190** & **EPC190** & **Judges** & **Cheeses** \\ \hline Intensity of odor & 5.32 \({}^{\mathrm{cd}}\) & 5.94 \({}^{\mathrm{bc}}\) & 6.22 \({}^{\mathrm{b}}\) & 6.78 \({}^{\mathrm{a}}\) & 5.06 \({}^{\mathrm{d}}\) & 5.76 \({}^{\mathrm{bd}}\) & 5.26 \({}^{\mathrm{cd}}\) & 5.91 \({}^{\mathrm{bc}}\) & 0.07 & 0.0  
Collectively our results demonstrate that polyphenols from GPP added into primosale cheese significantly boost antioxidant properties of the product, conferring to it potential capacity to control oxidative stress.