Microbiological quality of Port Salut Argentino cheese stored at two temperature treatments

Abstract

Microbiological quality of Port Salut Argentino cheese was studied during 10 days (after ripening) at two storage temperature treatments: (a) 4°C and (b) a temperature combination of both 4 and 20°C (4/20°C), which implied 12 h at 4°C and 12 h at 20°C. Total coliforms were not higher than 10 3 cfu/g among samples. E. coli was detected at both treatments. Thirty three percent of the cheese contained Staphylococcus aureus. Listeria spp. and Salmonella spp. were not detected in any treatment. Bacillus spp. incidence was 50% of the cheese, being B. cereus, B. cereus variety mycoides and B. pumilus. Bacillus cereus and Staphylococcus aureus grew at 4/20°C. Mesophilic aerobic bacteria were between 10 4 and 10 7 cfu/g. At 4/20°C counts decreased. At 4°C the behaviour was variable. Moulds were lower than 10 4 cfu/g and yeasts were between 10 4 and 10 5 cfu/g. pH, moisture content and tritatable acidity ranges of samples were 5.5–6, 51–52.3% and 1.215–1.935 g/100 g of lactic acid, respectively. Manufacturing of this cheese includes a short heat treatment and starter culture addition; consequently, our results indicate that this processing may be insufficient for achieving hygienic cheese production. The storage at refrigeration temperature will not always guarantee the cheese safety and quality.