Effects of cell-free supernatants produced by lactic acid bacteria on the safety and quality of poultry meat

1. This research characterised cell-free supernatants (CFS) obtained from lactic acid bacteria (Leuconostoc pseudomesenteroides T139, Pediococcus acidilactici T115 and Streptococcus thermophilus T127) and examined the effects of CFS (10%) on the safety and quality of poultry meat stored at 4°C for 7 d.2. In the first stage of the study, metabolite production (exopolysaccharide, hydrogen peroxide and diacetyl production) and their bioactive properties (pH values, total acidity, total phenolic contents and antioxidant activities) were detected. In the second stage, poultry meat was inoculated with Escherichia coli O157:H7, Listeria monocytogenes and Salmonella Typhimurium (≈5 log CFU/g) using the spot inoculation method and the counts of pathogens were examined. In the final stage of the study, the counts of background microbiota (total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria, Pseudomonas spp. Enterobacteriaceae and lactic acid bacteria) were determined.3. The amounts of exopolysaccharide, hydrogen peroxide and diacetyl were in the range of 156.00-514.30 µg/ml, 0.01-0.07 µg/ml and 19.15-75.54 ng/ml, respectively. The pH values, total acidity, total phenolic contents and antioxidant activities (DPPH and ABTS⁺ radical scavenging activities) of the CFS were in the range of 4.08-4.34, 1.78-1.87 g lactic acid/100 ml, 3549-3864 mg GAE/l, 30.42-37.76% and 21.78-31.41%, respectively. In the second stage of the study, the counts of E. coli O157:H7, L. monocytogenes and S. Typhimurium inoculated on poultry meats were reduced by CFS treatment in the range of 0.82-1.41, 0.77-2.11 and 0.71-1.78 log CFU/g, respectively. In the final stage of the study, the counts of background microbiota on CFS-treated poultry meat samples were efficiently decreased during storage period (4°C for 7 d).4. The current study revealed that CFS are highly effective for ensuring meat safety and improving quality.