Veterinary Research Forum

Abstract Chicken fillet is a suitable medium for growth and activity of different types of microorganisms. The pH and nutrients content of fillets are the most important factors in their microbial spoilage and degradation during cold storage at the retail level. In this regard, the uses of edible coatings containing antimicrobial and antioxidant compounds are effective approaches to maintain the quality of fillets. In this study the inhibitory effect of edible coating materials based on chia seed mucilage containing 0.00%, 0.25% and 0.50% zinc oxide nanoparticles (ZnO-NPs) on microbial growth and chemical spoilage as well as enhancing shelf life of chicken fillets during refrigerated storage for 20 days was investigated. The results of X-Ray diffraction confirmed the dispersion of ZnO-NPs on the chia seed mucilage matrix. Also, the number of total aerobic mesophilic and psychrophilic bacteria, coliforms and lactic acid bacteria, and the pH, total volatile nitrogen, peroxide and free fatty acids indexes in the control fillets were significantly increased compared to the fillets coated with chia seed mucilage during storage. While, in the samples coated with chia mucilage containing ZnO-NPs the number of the above-mentioned bacteria decreased in the first stage and then significantly increased during storing. Based on our findings, the shelf life of fillets could be increased at least 20 days by coating them with the chia seed mucilage containing ZnO-NPs.

Abstract In the present study, the effect of different concentrations of cell-free supernatant (CFS; 10.00 and 35.00 mg g^-1) of Lactobacillus salivarius (Ls-BU2) on chemical, microbial and sensorial specifications of ground beef stored under the refrigerated condition was investigated. The antibacterial activity of CFS on Escherichia coli was also assessed. According to agar-disk diffusion method, CFS of Ls-BU2 revealed a promising antibacterial activity against E. coli in culture media compared to CFS of a well-known probiotic (L. acidophilus LA-5). In meat, CFS of Ls-BU2 showed a minimal effective concentration (MEC) of 35.00 mg g^-1 on E. coli, while CFS of L. acidophilus represented a MEC of > 45.00 mg g^-1. The CFS of Ls-BU2 at 35.00 mg g^-1 concentration retained psychrophilic counts of meat at a lower value than maximum accepted level (7 log₁₀ CFU g^-1). In a similar trend, CFS of Ls-BU2 at 35.00 mg g^-1 concentration was also displayed high sensorial scores compared to other CFS-treated samples. In conclusion, we demonstrated that CFS of Ls-BU2 and to some extent CFS of L. acidophilus could act as a safe food additive for the control of bacterial pathogens and to extend the shelf life of ground beef.

Abstract Pomegranate juice (PJ) and its products are directly used in foods due to their pleasant taste and palatability as well as preservative effects. In spite of useful effects of essential oils such as zataria multiflora Boiss essential oil (ZEO) on prolonging shelf-life of foods, their application is restricted due to their vigorous taste and aroma. In the present study, physicochemical characteristics, chemical compositions and antioxidative activities of two Iranian native plants, PJ (Rabbab-e-Neyriz cultivar) and ZEO were investigated. 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power tests were used for measuring antioxidant activity. The level of total phenolic of them were also determined. Total soluble solids content, pH value, titratable acidity content and total anthocyanins content of PJ were also measured. Chemical compositions of ZEO were determined using Gas-chromatography, mass-spectrometry (GC-MS). The results of antioxidative tests indicated that the ZEO was significantly more potent (p < 0.05) than PJ. Also the phenolic content in ZEO (262.52 mg per g) was significantly higher (p < 0.05) than PJ (154.90 mg per 100g). Chemical compositions analysis of ZEO indicated that its major components were carvacrol (59.17%), linalool (23.67%), trans-caryophyllene (3.07%) and carvacrol methyl ether (2.44%). In the present study, physicochemical and antioxidative characteristics of Rabbab-e-Neyriz PJ were determined for first time. It was aslo found that ZEO in comparison with PJ had higher antioxidative activity and total phenolic content.