Total phenolic content and antioxidant properties of hard low-fat cheese fortified with catechin as affected by in vitro gastrointestinal digestion

- Catechin enhances the antioxidant activity in cheese.
- Most of the catechin was recovered in cheese under digestive conditions.
- Total phenolic content is highly correlated with antioxidant activity.
- Catechins are released through enzymatic hydrolysis in a simulated digestion system.

The total phenolic content (TPC) and antioxidant activity (AA) of a low-fat hard cheese fortified with different concentrations of catechin was examined over 90 days of ripening after in vitro digestion of cheese samples. TPC and AA increased in cheese after manufacturing and over the ripening period at 8 °C. Prior to analysis, the cheese samples were subjected to a two-stage in vitro digestion with gastric and intestinal phases to simulate human digestive conditions. The AA, measured as both ferric reducing antioxidant power and oxygen radical absorbance capacity, showed a high degree of correlation (R2 > 0.89) with the TPC results. The in vitro recovery fraction of catechin after 90 days of ripening was 0.607, 0.628 and 0.752 for the cheeses fortified with catechin at 125, 250 and 500 mg kg−1, respectively. This study shows the feasibility of incorporating phenolic antioxidants into a protein-rich food, such as cheese, and maintaining antioxidant activity after digestion.