Inocuidad microbiológica de quesillos comerciales y artesanales expendidos en chillán

Abstract

Introduction: Fresh cheese is consumed because of its healthy, nutritional, and safety characteristics. These features become less relevant when appropriate preparation and storage conditions are not met. Objective: The objective was to evaluate the microbiological safety of commercial and artisanal fresh cheeses sold in the city of Chillán. Methods: A total of 80 fresh cheese samples were analyzed: 40 commercial (brands 1 and 2) and 40 artisanal (brands 3 and 4). Enterobacteriaceae (ENT) and Escherichia coli were quantified by NCh 2676 and 2636 (2002). Salmonella, Staphylococcus aureus, and Listeria monocytogenes used NCh 2675, 2671 (2002), ISO 11290-1 (1996 rev 2004), and were confirmed by PCR. Cronobacter spp was identified by multilocus sequence typing (MLST) using criteria from http://www.pubmlst. org/cronobacter. Furthermore, staff and sale hygiene requirements were identified with Sanitary Food Regulations (SFR) checklists. Results: Overall ENT medians were 30 000 000 UFC/g (2 000 000 - 300 000 000) and E. coli were 450 UFC/g NMP/g (33 - 1 100); there were no significant differences in counts for both brand and sale location indicators (p>0.05). Compliance with SFR hygiene requirements was 50%. Positivity of L. monocytogenes was 8.8%; Salmonella spp and S. aureus were not detected. Suspected Cronobacter spp strains were isolated and identified as Franconibacter helveticus. Conclusions: The evaluated fresh cheeses did not meet SFR microbiological criteria and were therefore not safe to eat. The presence of L. monocytogenes is clearly a health risk in hypersensitive population groups that consume this food.