Capability of acidic electrolyzed water in the elimination of Salmonella Typhimurium and Escherichia coli in the chicken breast

Aims@#This study aimed to investigate the effect of acidic electrolyzed water (AEW) as pre-refrigeration and pre-freezing processing steps for chicken meat in regard to the behavior of S. Typhimurium and E. coli during storage.@*Methodology and results@#AEW (free available chlorine 30 ppm and pH 2.7) was tested against S. Typhimurium and E. coli in growth media (brain heart infusion broth) and by exposing inoculated chicken fillets. The in vitro study appointed 10 minutes as the straightening exposure time of fresh prepared AEW for S. Typhimurium and E. coli. The reduction effect of AEW was significant (p<0.05) for both S. Typhimurium and E. coli along the 8 days of refrigerated storage with a maximum reduction after 24 h of post-treatment reaching 23.3% (1.4 log CFU/g) and 32.43% (2.15 log CFU/g) for S. Typhimurium and E. coli, respectively. AEW resulted in a significant reduction (p<0.05) as a pre-freezing application for both microorganisms, where the maximum reductions of 20% (1.2 log CFU/g) and 31.84% (2.14 log CFU/g) for S. Typhimurium and E. coli, respectively, were reported at zero time (just after dipping). In exposed samples to AEW, S. Typhimurium could not be detected by the 6th week of frozen storage while E. coli continued detectable until till 10th week but with a reduced population of 30% compared to control.@*Conclusion, significance and impact of study@#The findings of the present study suggest the application of AEW as a pre-refrigeration and pre-freezing treatment for chicken products. AEW application significantly improved the safety of chicken products.

Antibiofilm activity of carvacrol loaded chitosan nanoparticles against Listeria monocytogenes

Aims@#This study was designed to evaluate the effectiveness of the synthesised carvacrol loaded chitosan nanoparticles (CLCNPs) on the growing and pre-formed biofilms of Listeria monocytogenes isolated from slaughterhouses.@*Methodology and results@#The swab samples were collected from knives, hocks and cutting tables representing slaughterhouses meat contact surfaces (MCS), while those samples from walls and floors represent slaughterhouses meat non-contact surfaces (MNCS). The bacteriological analysis revealed the existence of L. monocytogenes with a prevalence rate of 3.3, 10 and 6.7% for knives, hocks and cutting tables, respectively and 2.2 and 6.6% for walls and floors, respectively. The isolates L. monocytogenes were assayed for biofilm production by the crystal violet binding assay method. Among the 10 L. monocytogenes isolates, 10%, 50% and 30% of the isolates were found to be strong, moderate and weak biofilm producers, respectively. The activities of carvacrol, chitosan nanoparticles (NPs) and CLCNPs against the only strong biofilm producer strain of L. monocytogenes were tested by microtiter plate assay. The minimum inhibitory concentrations (MIC) values were 3.75 mg/mL for CAR, 5 mg/mL for chitosan NPs and 0.62 mg/mL for CLCNPs. CLCNPs inhibit the produced biofilm by 35.79, 73.37 and 77.76%, when 0.5 MIC, 1 MIC and 2 MIC were used, respectively. Furthermore, the pre-formed L. monocytogenes biofilms were significantly reduced from 1.01 (control) OD570 to 0.40 and 0.29 OD570 by applying 2 MIC and 4 MIC doses, respectively.@*Conclusion, significance and impact of study@#The data generated is promising to develop bio-green disinfectants to inhibit biofilm formation by L. monocytogenes in the food processing environment and control its adverse effects for consumers.