Supplementation of olive oil-derived phytocomplexes in broiler chicken diets: effects on breast meat quality and oxidation changes of thigh meat during refrigerated storage

Chicken meat is rich in unsaturated fatty acids and heme pigments (especially in leg meat) that makes it particularly susceptible to the development of oxidative reactions, which are one of the main causes of meat quality deterioration and losses at retail, food service and households. This study aimed at assessing the effect of the dietary supplementation of two natural phytocomplexes resulting from the production of olive oil on the main quality traits of fresh chicken meat as well as on the oxidative phenomena that develop during refrigerated storage. A total of 2,340 one-day-old Ross 308 male chicks was divided into 3 experimental groups and fed a commercial corn-wheat-soybean diet (CON) or the same diet supplemented in all feeding phases (0-42d) with the two phytocomplexes (P1 and P2). At slaughter, 12 carcasses/group were collected and cut to excise the breast fillets and the thighs. Fillets were used to assess the main quality traits (pHu, colour, drip and cooking losses, tenderness) of fresh meat, whereas the thighs, packaged in ordinary atmosphere, were used to measure potential changes due to oxidation (colour, carbonyls, thiols, and myoglobin oxidative status) at 0, 3, and 6 days of refrigerated storage (4 1°C). Data were analysed by ANOVA and Tukey-HSD test considering the effects of dietary treatment and storage time. Supplementing the diet with P1 and P2 did not significantly affect the main quality traits and technological properties of breast meat. On the contrary, the dietary utilization of phytocomplexes remarkably changed the colour parameters of thigh meat. Indeed, if compared with CON, P1 and P2 exhibited higher lightness (L*;48.0 vs. 49.7 and 49.4, respectively; p<0.001) and lower redness values (a*; 4.2 vs. 3.3 and 3.3, respectively; p<0.001). As for the main effect of the storage time, most of the changes occurred within the first 3 d of storage in which an increase in the values of all colour parameters has been observed (p<0.001). Considering the oxidation of the protein and lipid fractions, these reactions developed during the refrigerated storage and no differences ascribable to the use of the tested phytocomplexes were detected. These results suggest that the dietary supplementation of natural phytocomplexes obtained as by-products of olive oil production had no substantial effects on the oxidative stability of chicken meat.