Effect of dietary thymol supplementation on lipid oxidation of chicken legs as related to storage conditions

The aim of this research was to evaluate the effect of dietary thymol supplementation on lipid oxidation of chicken leg meat during refrigerated shelf-life. Chickens belonging to Ross 308 hybrid were raised under experimental conditions up to 3 kg of live weight, using three dietary treatments: control (without supplementation, C), treatment 1 (C+0.1% w/w thymol supplementation, T1) and treatment 2 (C+0.2% w/w thymol supplementation, T2). After slaughtering, the chicken legs with skin were stored under conventional (CON) and modified atmosphere (MAP) at temperature of 2-4°C for 14 days. Lipid oxidation was monitored by the determination of primary (peroxide value, PV) and secondary (thiobarbituric acid reactive substances, TBARs) products at 3, 7, 10 and 14 days of storage under both CON and MAP conditions and compared with values found on fresh meat. The three different dietary treatments did not significantly affect the lipid oxidation parameters. PV ranged between 0.5-13.0, 0.7-13.0 and 1.0-11.0 meq O2/kg of lipid in poultry meat obtained with C, T1 and T2 diets, respectively. TBARs varied between 0.1-0.7, 0.1- 0.6 and 0.2-0.5 mg MDA/kg of meat in poultry meat obtained with C, T1 and T2 diets, respectively. On the other hand, interaction effect of diets and storage conditions were significant (P≤0.05) in PV formation, as it was delayed under MAP (maximum PV level after 2 and 5 days of storage in C and thymol-containing diets, respectively) with respect to conventional storage (PV apex after 2 days of storage). However, not significant differences (P≥0.05) were found on TBARs level as related to storage conditions. In conclusion, this study demonstrated that dietary thymol supplementation coupled to MAP storage conditions delay lipid oxidation of chicken legs with skin, thus improving their shelf-life.