The effect of separate and combined treatments of nisin, Rosmarinus officinalis essential oil (nanoemulsion and free form) and chitosan coating on the shelf life of refrigerated chicken fillets

As revealed by various studies, Rosemary (Salvia rosmarinus) extract has antioxidant and antimicrobial properties. Moreover, nisin is a bacteriocin with antibacterial properties. The present study aimed to design a natural conservative with the engagement of the synergistic effect of nisin, different forms of essential oil, and chitosan coating on the chicken fillet during refrigeration. In this study, we evaluated the treatments of distilled water (DW), nisin (N), free form of rosemary (FRR), and the nano-emulsion of rosemary (NER) as well as combined treatments of nisin and free form of rosemary (N + FRR) and nisin and nano-emulsion of rosemary (N + NER). The assessments were carried out on days 0, 3, 6, 9, and 12. The results indicated significant efficiency of NER and FRR and also a higher efficiency in the combined (N + NER) and (N + FRR) treatments in improving the microbiological, chemical, and sensory properties of the samples compared to the DW treatment during the storage time (P < 0.05). After 12 days, (N + NER) superiority in chemical and microbial quality is reflected in the mesophilic population and thiobarbituric acid index, which were 7.19 ± 0.05 log CFU/g, 0.64 ± 0.01 mg MDA/Kg respectively. The combined (N + NER) was selected as the optimal treatment in the first phase of the current research. In the second phase, the (N + NER) treatment was covered with chitosan coating and formed a separate treatment (OC) to also examine the effect of this coating individually. Based on the results, the OC treatment managed to more effectively boost microbial, chemical and sensory properties of sample compared to the (N + NER).