title: Total mesophilic counts underestimate in many cases the contamination levels of psychrotrophic lactic acid bacteria (LAB) in chilled-stored food products at the end of their shelf-life.
abstract: The major objective of this study was to determine the role of psychrotrophic lactic acid bacteria (LAB) in spoilage-associated phenomena at the end of the shelf-life of 86 various packaged (air, vacuum, modified-atmosphere) chilled-stored retail food products. The current microbiological standards, which are largely based on the total viable mesophilic counts lack discriminatory capacity to detect psychrotrophic LAB. A comparison between the total viable counts on plates incubated at 30 °C (representing the mesophiles) and at 22 °C (indicating the psychrotrophs) for 86 food samples covering a wide range - ready-to-eat vegetable salads, fresh raw meat, cooked meat products and composite food - showed that a consistent underestimation of the microbial load occurs when the total aerobic mesophilic counts are used as a shelf-life parameter. In 38% of the samples, the psychrotrophic counts had significantly higher values (+0.5-3 log CFU/g) than the corresponding total aerobic mesophilic counts. A total of 154 lactic acid bacteria, which were unable to proliferate at 30 °C were isolated. In addition, a further 43 with a poor recovery at this temperature were also isolated. This study highlights the potential fallacy of the total aerobic mesophilic count as a reference shelf-life parameter for chilled food products as it can often underestimate the contamination levels at the end of the shelf-life.
authors.affiliation: Laboratory of Food Microbiology and Food Preservation, Member of Food2know, Department of Food Safety and Food Quality, Ghent University, Coupure Links 653, 9000 Ghent, Belgium. Vasileios.Pothakos@UGent.be
authors.forename: Vasileios
authors.initials: V
authors.lastname: Pothakos
authors.forename: Simbarashe
authors.initials: S
authors.lastname: Samapundo
authors.forename: Frank
authors.initials: F
authors.lastname: Devlieghere
mesh_terms: D000818:Animals; D001419:Bacteria / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D003080:Cold Temperature; D003257:Consumer Product Safety; D057140:Fast Foods / Q000382:microbiology*; D005506:Food Contamination / Q000032:analysis*; D018857:Food Packaging; D061353:Food Storage; D019344:Lactic Acid / Q000378:metabolism; D008460:Meat / Q000382:microbiology; D013696:Temperature; D014675:Vegetables / Q000382:microbiology*
chemical_list: D019344:Lactic Acid