Growth and survival of Escherichia coli O157:H7 during the manufacture and ripening of raw goat milk lactic cheeses.
The behaviour of Escherichia coli O157:H7 was studied during the manufacture and ripening of raw goat milk lactic cheeses. Cheese was manufactured from raw milk in the laboratory and inoculated with E. coli O157:H7 to a final concentration of 10, 100 and 1000 cfu ml(-1). E. coli O157:H7 was counted by CT-SMAC (Mac Conkey Sorbitol Agar with cefixim and tellurite) and O157:H7 ID throughout the manufacturing and ripening processes. When the milk was inoculated with 10, 100 or 1000 cfu ml(-1), counts decreased to less than 1 log(10) g(-1) in curds just prior to moulding. However, viable E. coli O157:H7 were found in cheeses throughout processing, and even after 42 days of ripening. Results indicate that E. coli O157:H7 survives the lactic cheese manufacturing process. Thus, the presence of low numbers of E. coli O157:H7 in milk destined for the production of raw milk lactic cheeses can constitute a threat to the consumer.
Vernozy-Rozand
C
C
Unité de Microbiologie Alimentaire et Prévisionnelle, Ecole Nationale Vétérinaire de Lyon, Marcy l'Etoile, France. c.vernozy@vet-lyon.fr
Mazuy-Cruchaudet
C
C
Bavai
C
C
Montet
M P
MP
Bonin
V
V
Dernburg
A
A
Richard
Y
Y
D000818:Animals; D002611:Cheese / Q000382:microbiology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D019453:Escherichia coli O157 / Q000254:growth & development*; D005285:Fermentation; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006041:Goats; D006801:Humans; D008892:Milk / Q000382:microbiology