Gastro-pancreatic release of phenolic compounds incorporated in a polyphenols-enriched cheese-curd

- Cheese curd was enriched with different phenolic compounds.
- Polyphenols showed high retention coefficient in curd.
- Retention coefficient depended on the binding with casein and on the hydrophilicity.
- Phenolic compounds addition increased the antioxidant activity.
- Phenolic compounds were released from curd during in vitro digestion.

As functional food, enriched cheese has recently been developed. The main objectives of this study were to investigate the role of casein in the retention of polyphenol during curd formation and the release of polyphenols during in vitro gastro-pancreatic digestion of polyphenols-enriched cheese and their contribution to the antioxidant activity of digested curd. Polyphenols showed high retention coefficient in curd. The retention coefficient of polyphenol was related to the binding affinity to casein and to their hydrophilicity. The polyphenols should be added before milk coagulation since the binding decreases as casein molecules aggregate. During in vitro gastro-pancreatic digestion steps, polyphenols were released from curd due to the dilution in gastric fluid and to casein proteolysis. The addition of polyphenols to curd determined a relevant increase of antioxidant activity respect to the curd control even a part of polyphenols is degraded by alkaline pH of pancreatic fluid. Our results suggested the possibility of producing highly nutritive value cheese with high release of the polyphenols during digestion. In addition, the whey, which contains polyphenols, can be involved in different products to maximize its utilization.