Growth and enterotoxin production of Staphylococcus aureus during themanufacture and ripening of Camembert-type cheeses from raw goats' milk

摘要

Tests were carried out to determine the effect of manufacturing procedures for a Camembert-type cheese from raw goats' milk on the growth and survival of Staphylococcus aureus organisms added to milk at the start of the process, and to study the possible presence of staphylococcal enterotoxin A in these cheeses. The initial staphylococcal counts were, respectively, 2, 3, 4, 5 and 6 log cfu ml(-1). Cheese was prepared following the industrial specifications and ripened for 41 d. Detection of enterotoxins was done by the Vidas SET test and by an indirect double-sandwich ELISA technique using antienterotoxin monoclonal antibodies. Generally, numbers of microbes increased at a similar rate during manufacture in all cheeses until salting. During the ripening period, the aerobic plate count population and Staph. aureus levels remained stable and high. There was an approximately 1 log reduction of Staph, aureus in cheeses made with an initial inoculum of Staph. aureus greater than 10(3) cfu ml(-1) at the end of the ripening period (41 d) compared with the count at 22 h. The level of staphylococcal enterotoxin A recovered varied from 1 to 3.2 ng g(-1) of cheese made with an initial population of 10(3)-10(6) cfu ml(-1). No trace of enterotoxin A was detected in cheeses made with the lowest Staph. aureus inoculum used in this study.