The antioxidant activity of carnosine and its consequences on the volatile profiles of liposomes during iron/ascorbate induced phospholipid oxidation

The natural dipeptide L-carnosine (β-Ala-His) exhibits antioxidative properties and can be used as an antioxidant in food products. Its antioxidant activity and its effect on the volatile compounds produced during lipid oxidation was studied in a meat-related model system (liposomes of muscle phospholipids). Oxygen uptake, conjugated dienes, trienes and ketodienes, thiobarbituric acid reactive substances (TBARS) and volatile compounds were measured after induction of oxidation by equimolar Fe(III)/ascorbate (45 μM). ion of carnosine (2–10 mM) lead to a decrease in all indices of lipid oxidation, except for the initial rate of oxygen uptake, which increased, and the rates of oxygen uptake 5 or more min after catalyst injection, which remained constant. The decrease varied as a function of carnosine concentration, method of measurement and incubation time. When carnosine was added to previously oxidised liposomes, TBARS, t-2-undecenal, total 2-alkenals and hexanol amounts decreased significantly. ine antioxidant activity is multifunctional: it has a buffering effect; it interferes in the initiation step of oxidation; it decreases the amount of preformed peroxides; it reacts with some secondary products.