THE ANTIOXIDANT ACTIVITY OF CARNOSINE AND ITS CONSEQUENCES ON THE VOLATILE PROFILES OF LIPOSOMES DURING IRON ASCORBATE INDUCED PHOSPHOLIPIDOXIDATION/

The natural dipeptide L-carnosine (beta-Ala-His) exhibits antioxidativ e properties and can be used as an antioxidant in food products. Its a ntioxidant activity and its effect on the volatile compounds produced during lipid oxidation was studied in a meat-related model system (lip osomes of muscle phospholipids). Oxygen uptake, conjugated dienes, tri enes and ketodienes, thiobarbituric acid reactive substances (TBARS) a nd volatile compounds were measured after induction of oxidation by eq uimolar Fe(III)/ascorbate (45 mu M). Inclusion of carnosine (2-10 mM) lead to a decrease in all indices of lipid oxidation, except for the i nitial rate of oxygen uptake, which increased, and the rates of oxygen uptake 5 or more min after catalyst injection, which remained constan t. The decrease varied as a function of carnosine concentration, metho d of measurement and incubation time. When carnosine was added to prev iously oxidised liposomes, TBARS, t-2-undecenal, total 2-alkenals and hexanol amounts decreased significantly. Carnosine antioxidant activit y is multifunctional: it has a buffering effect; it interferes in the initiation step of oxidation; it decreases the amount of preformed per oxides; it reacts with some secondary products. (C) 1997 Elsevier Scie nce Ltd.