A survey of soft cheeses in Greek retail outlets highlights a low prevalence of Listeria spp.

Abstract

Recently, the European Food Safety Authority proposed that each EU member state should conduct a survey of Listeria monocytogenes in soft cheeses for sale in retail outlets. Hence, retail samples of soft cheeses in Greece (n = 137) were analyzed qualitatively and quantitatively for both L. monocytogenes and other Listeria spp., as well as for pH and a w. None of the cheeses analyzed were found positive for L. monocytogenes (0%; 95% confidence interval (CI) = 0.0–2.2%). Three samples (2.2%; 95% CI = 0.5–6.3%) were positive for other Listeria spp., with populations ranging from <5 to 4.5 × 102 CFU g−1. Although soft cheeses are regarded as foods that permit the proliferation of L. monocytogenes, 15.4% of the whey cheeses tested had pH values ≤4.4 and 29% of the interior mold-ripened cheeses had a w values ≤0.92. Such low pH values for whey cheeses are unexpected, based on their manufacturing technology, and are associated with lower quality and reduced shelf life. Nonetheless, in the present survey, the percentage of whey cheeses in the Greek retail market exhibiting unusually low pH values or testing positive for Listeria spp. was much lower compared to the respective percentages reported from studies conducted in the 1990s. The absence of L. monocytogenes in the tested cheeses undoubtedly constitutes an encouraging result with respect to the safety of soft cheeses in the Greek retail market. However, the presence of other Listeria spp. in three of the tested samples implies that L. monocytogenes would, most likely, also be present in the food-processing or retail-handling environments of these products. Therefore, cheese manufacturers and retail handlers should continue or even intensify the application of all necessary measures with the aim of preventing food contamination.