Protective effects of dietary carnosine during in-vitro digestion of pork differing in fat content and cooking conditions.

ABSTRACT

Muscle carnosine represents an important health advantage of meat. Ground pork samples with intrinsic or added carnosine; fat content; and cooked under low or high intensity as a 2 × 2 × 2 factorial were digested in-vitro. Changes in free carnosine and in markers of lipid (hexanal, 4-hydroxynonenal (4-HNE), malondialdehyde (MDA) and protein (protein-carbonyls, thiols) oxidation, and of advanced glycation end-products (AGEs) Nε -(carboxymethyl)lysine (CML) were determined in the saliva, gastric, and duodenal digests. During digestion, the different markers overall indicated increased oxidation and decreased free carnosine. Increasing pork carnosine level significantly reduced protein carbonyls, loss of thiols, and 4-HNE during in-vitro gastric digestion, irrespective of fat and cooking level of the meat. Increased carnosine also significantly reduced hexanal, MDA and CML up to the duodenum phase in moderately cooked lean pork. Besides substantiating the formation of AGEs during digestion, these results show a potentially important role of dietary carnosine occurring in the gastrointestinal tract. PRACTICAL APPLICATIONS The ailments epidemiologically associated with red meat consumption could be counteracted by ingesting carnosine into meat. The health advantages of dietary carnosine, however, have never been demonstrated during digestion, a unique and complex oxidative environment compounded by the composition and cooking of the meat. The results obtained substantiated that AGEs formation occurred in-vitro in the GIT. They also showed that increased carnosine had an immediate health beneficial role during pork digestion in reducing the formation of different harmful molecules, including AGEs, modulated by the composition and cooking of the meat. However, in exerting this protective role in the GIT, the remaining free level of carnosine, gradually decreased during digestion. Carnosine, as an important meat compositional factor may, depending on the fat content and cooking conditions, change the image of meat from representing a health risk to a health benefit. Carnosine level may also explain discrepancies observed in the literature.