Effect of rosemary essential oil as nitrite substitute on quality of sausage produced using chicken fed by thymus essential oil and rapeseed oil

The objective was to determine the effect of rosemary essential oil (REO) as nitrite substitute on the physicochemical, microbiological and sensory quality of sausage from broilers fed different levels of thymus essential oil (TEO) and rapeseed oil (RO). Broiler chicks fed TEO (0, 300 and 500 ppm) and RO (1, 3 and 5%) in a 3 × 3 factorial design. Sausages were made from meat of chicken fed TEO (0 and 500 ppm) treated with REO (120 ppm), REO:nitrite (60:60 ppm), nitrite (120 ppm) or without REO and nitrite in a 2 × 4 factorial design. Results showed that TEO increased water holding capacity and pH value and decreased malondialdehyde concentration. RO (1 and 3%) × TEO (500 ppm) group had higher unsaturated to saturated fatty acids ratio in the meat. Results showed that treatments of REO (120 ppm) decreased lipid oxidation and increased pH value of meat. Sausage produced by nitrite (120 ppm) or REO:nitrite (60:60 ppm) had lower total microbial count, lightness but higher redness and yellowness. Based on the results, TEO in chicken feed decreased lipid oxidation of sausages. Furthermore, substitution at least 60 ppm nitrite with REO had more preserving effect on quality of produced sausages.