Effect of cooking and simulated gastrointestinal digestion on the activity of generated bioactive peptides in aged beef meat

Ageing is widely used in the meat industry to improve tenderness mainly as a result of the breakdown of muscular proteins through the action of endopeptidases during storage time. In addition, meat contains a large pool of other proteolytic enzymes, mainly exopeptidases, which cut from the outer edges of proteins and polypeptides generating a vast array of peptides and free amino acids. Some of these peptides could potentially exert bioactivities of interest for human health. In this study, ACE-inhibitory and antioxidant activities during meat ageing in chilled-storage at 4 degrees C for a period of time of 0, 1, 2, 3 and 4 weeks have been determined. Beef loin steak samples were analysed before and after cooking, and gastrointestinal digestion was simulated in order to study its effect on the bioactivity. Control and cooked samples showed an increase in the ACE-inhibitory activity from the third week of chilled storage whereas non-significant differences in the antioxidant activity between control and cooked samples were detected during the studied time. After gastrointestinal digestion of samples, there was a significant increment of the ACE-inhibitory and antioxidant activities in comparison with control and cooked samples at all the studied times. As a main conclusion, cooking does not significantly influence the bioactivity detected whereas the in vitro gastrointestinal digestion produces a significant increase in the ACE-inhibitory and antioxidant activities from the first week, probably due to the intense generation of small peptides as a result of the action of gastrointestinal enzymes.