Assessment of Salmonella and Listeria monocytogenes level in ready-to-cook poultry meat: Effect of various high pressure treatments and potassium lactate concentrations

• Published in: International journal of food microbiology Vol. 186; pp. 74 - 83
• Main Authors: Lerasle, M., Guillou, S., Simonin, H., Anthoine, V., Chéret, R., Federighi, M., Membré, J.-M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2014; Elsevier
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; Biological and medical sciences; Computer Simulation; Cooking; Food and Nutrition; Food Handling - standards; Food industries; Food microbiology; Fundamental and applied biological sciences. Psychology; High pressure processing; Lactates - pharmacology; Life Sciences; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - isolation & purification; Meat - microbiology; Microbiology and Parasitology; Models, Biological; Modified atmosphere packaging; Poultry; Pressure; Probabilistic model; Salmonella; Salmonella - drug effects; Salmonella - isolation & purification; Modified atmosphere packaging; Probabilistic model; High pressure processing; Salmonella; Physical dressing; Meat product; Listeria monocytogenes; Concentration; High pressure; Lactates; Packaging; Bacteria; Conditioning; Modified atmosphere; Potassium; Poultry meat; Enterobacteriaceae
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2014.06.019

The objective of this study was to develop a probabilistic model in order to determine the contamination level of Salmonella and Listeria monocytogenes in ready-to-cook poultry meat, after a high pressure (HP) treatment. The model included four steps: i) Reception of raw meat materials, mincing and mixing meat, ii) Partitioning and packaging into 200-g modified atmosphere packs, iii) High pressure treatment of the meat, and iv) Storage in chilled conditions until the end of the shelf-life. The model excluded the cooking step and consumption at consumer's home as cooking practices and heating times are highly variable. The initial contamination level of Salmonella and L. monocytogenes was determined using data collected in meat primary processing plants. The effect of HP treatment and potassium lactate on microbial reduction was assessed in minced meat, using a full factorial design with three high pressure treatments (200, 350 and 500MPa), three holding times (2, 8 and 14min) and two potassium lactate concentrations (0 or 1.8% w/w). The inactivation curves fitted with a Weibull model highlighted that the inactivation rate was significantly dependent on the HP treatment. From the literature, it was established that Salmonella was not able to grow in the presence of lactate, under modified atmosphere and chilled conditions whereas the growth of L. monocytogenes was determined using an existing model validated in poultry (available in Seafood Spoilage and Safety Predictor software, V. 3.1). Once implemented in the Excel add-in @Risk, the model was run using Monte Carlo simulation. The probability distribution of contamination levels was determined for various scenarios. For an average scenario such as an HP treatment of 350MPa for 8min, of 200g minced meat containing 1.8% lactate (pH6.1; aw 0.96), conditioned under 50% CO2, the prevalence rate of Salmonella and L. monocytogenes, after a 20-day storage at 6°C was estimated to be 4.1% and 7.1%, respectively. The contamination level was low considering that the product is going to be cooked by the consumer afterwards: the 99th percentile of the distribution was equal to −2.3logcfu/g for Salmonella and 0.5logcfu/g for L. monocytogenes. More generally, the model developed here from raw material reception up to the end of the shelf-life enables to recommend combinations of HP treatment and lactate formulation to guarantee an acceptable microbial concentration before cooking. •A probabilistic model of Salmonella and L. monocytogenes was built.•The varying factors were high pressure treatment, potassium lactate and product shelf-life.•The fixed factors were pH, aw, CO2 in atmosphere packaging and storage temperature.•The level of Salmonella in ready-to-cook poultry meat was <1cfu/g.•The level of L. monocytogenes in ready-to-cook poultry meat was <10cfu/g.