Effect of coating eggs with black seed oil containing rosemary essential oil on its quality characteristics during the storage

In the present study, the eggs were coated individually with black seed oil (BSO) or with combination of rosemary essential oil (REO). The eggs were coated with BSO incorporated with 1, 2 and 3% REO and stored for 6 weeks. The results showed that shell thickness of coated eggs called BSO-3%REO was 55 μm which was higher than control (45 μm). After 6 weeks of storage, the Haugh Unit and egg yolk index of control eggs were 21 and 0.16, while for coated eggs with BSO-3%REO were 33 and 0.23, respectively. The pH of albumin and egg yolk were 8.19 and 5.56 in control which reached 9.59 and 7.24 after 6 weeks while 9.04 and 7.19 were obtained for BSO-3%REO coated eggs. The albumin foaming and its stability were 8.37 mL/g and 25.03% for control on the first day which decreased to 3.19 mL/g and 14.90% after 6 weeks while coating delayed the foam deterioration up to 4.72 mL/g and 17.23% during the storage period. Coating with BSO incorporated with 3% of REO had significant effects on aerobic mesophilic and psychrophilic bacteria while no considerable effects were observed on gram negative S. enteritidis . Taking into account, it seems that coating fresh eggs with BSO incorporated with 2 or 3% REO can extend the shelf life of eggs for 3 weeks while minimal changes occur in the quality characteristics.