Kinetics of malonaldehyde content in enriched chicken meat during isothermal cooking

Lipid oxidation is a standard parameter in the evaluation of meat quality. It is most often used when the composition of the meat is modified, either by changing the animal's diet or by adding food supplements during post-slaughter meat processing. Malonaldehyde (MA) is commonly accepted as the main lipid oxidation product in meat. In this study, changes in MA contents in chicken meat enriched with n3-PUFA during cooking were analysed. Small samples (1.5g) of ground chicken thighs were placed in plastic bags, wrapped in thin film, and immersed in a water bath at different temperatures (50, 70 and 100 degrees C) for cooking times ranging from 0 to 30min. MA content was measured by liquid chromatography. MA content first increased rapidly and then decreased. The kinetics were fitted to a model using sequential first-order reactions including appearance and disappearance rate constants. The temperature influenced the rate constants according to Arrhenius' law, with the highest activation energy for the appearance rate constant. An increase in the vitamin E content of the meat reduced the appearance rate but not the disappearance rate constant. Practical applications: This study investigates the possibility of modelling the MA content in n3-PUFA enriched chicken meat during cooking in order to predict the lipid oxidation state of the meat consumers would eat. By understanding the mechanisms of MA appearance and disappearance reactions according to the level of antioxidant present in the meat, this study enables to monitor the lipid oxidation extent. The utility of vitamin E as an antioxidant in n3-PUFA enriched chicken meat is demonstrated. This study also enlightens the behaviour of the MA, the compound most widely used in literature to characterize the lipid oxidation extent, which is a transition product and must be used with care. In fact, it is clearly shown that a single value of MA content cannot express an oxidation state due to cooking without prior focus on the complete kinetics to determine the appearance and disappearance phases of the MA.