Summary -The effects of storage atmosphere and temperatures on Salmonella typhimurium and aerobic plate count (APC) in meat were studied. Experimental results were analysed by non-linear regression of modified-Gompertz and logistic equations to generate "best fit". In the absence of CO 2 in package (with air and 40% O 2 + 60% N 2 ), in the refrigerator and at 12 o C, S. typhimurium had higher growth rate and reached to higher number, whereas the presence of CO 2 from 40 to 100% reduced the number of S. typhimurium by 0.2 to 1.6 logs unit in the refrigerator. CO 2 dissolves in water to form carbonic acid which reduces pH of meat and bacterial cytoplasm. This would be reduced the bacteria or inhibited their growth. The effects of the modified atmospheres on microorganisms in meat seems to be responsible for the data obtained, together with a probable contribution from pH which in turns is likely to be influenced by the gas atmosphere. It is known that CO 2 has a bacteriostatic effect. Parameters of non-linear modified-Gompertz and logistic models of the S. typhimurium and APC in meat stored at various atmospheres were matched in a satisfactory way. Both the modified-Gompertz and logistic models showed good fit to all curves as assessed using the root mean square error and the correlation coefficient between the experimental and predicted values.

No abstract

Antimicrobial edible coatings can eliminate the risk of pathogen contamination on the surface of poultry products during storage. In this study, an edible coating (EC) based on wheat gluten, Pistacia vera L. tree resin (PVR), and the essential oil (EO) of PVR was applied on chicken breast fillets (CBF) by a dipping method to prevent the growth of Salmonella Typhimurium and Listeria monocytogenes. The samples were packed in foam trays wrapped with low-density polyethylene stretch film and stored at 8 °C for 12 days to observe the antimicrobial effects and sensory properties. The total bacteria count (TBC), L. monocytogenes, and S. Typhimurium were recorded during storage. The samples coated with EC, containing 0.5, 1, 1.5, and 2% v/v EO (ECEO), showed significant decreases in microbial growth compared to the control samples. The growth of TBC, L. monocytogenes, and S. Typhimurium was suppressed by 4.6, 3.2, and 1.6 logs, respectively, at the end of 12 days on the samples coated with ECEO (2%) compared to the uncoated controls (p < 0.05). Coating with ECEO (2%) also preserved the appearance, smell, and general acceptance parameters better than uncoated raw chicken (p < 0.05) on the fifth day of storage. In grilled chicken samples, ECEO (2%) did not significantly change the appearance, smell, and texture (p > 0.05) but increased the taste and general acceptance scores. Therefore, ECEO (2%) can be a feasible and reliable alternative to preserve CBFs without adversely affecting their sensory properties.

Antimicrobial edible coatings could eliminate pathogen contamination risk on the surface of meat and poultry products during storage. In this study, the edible coating (EC) based on wheat gluten, Pistacia vera L. tree resin (PVR), and essential oil (EO) of PVR were applied on chicken breast fillets (CBF) by dipping method to prevent the growth of Salmonella Typhimurium and Listeria monocytogenes. The samples were packed in foam trays wrapped with low-density polyethylene stretch film and stored at 8°C for 12 days to observe antimicrobial effects and sensory properties. The total bacteria count (TBC), L. monocytogenes, and S. Typhimurium were reported during the storage. All samples coated with EC containing 0.5, 1, 1.5, and 2% v/v EO (ECEO) decreased microbial growth significantly compared to control samples. The growth of TBC, L. monocytogenes, and S. Typhimurium was suppressed by 4.6, 3.2, and 1.6 logs, respectively, at the end of 12 days on the samples coated by ECEO (2%) compared to uncoated controls (p&amp;lt;0.05). Coating with ECEO (2%) also preserved appearance, smell, and general acceptance parameters better than uncoated raw chicken (p&amp;lt;0.05) on the 5th day of storage. In grilled chicken samples, ECEO (2%) did not significantly change the sensory properties of appearance, smell, and texture but had increased taste and general acceptance scores (p&amp;gt;0.05). So, ECEO (2%) can be a feasible and reliable alternative to preserve chicken breast fillets without affecting their sensory properties adversely during the shelf life.