Comparison of growth characteristics and roquefortin C production of Penicillium roqueforti from blue-veined cheese

POSE G.; LUDEMANN V.; GOMEZ A.; SEGURA J.

Mycotoxin Research

Hans W. Schmidt Ed.

Año: 2007 vol. 23 p. 122 - 126

0178-7888

The properties of 21 isolates of Penicillium roqueforti from just as many commercial blue-veined cheeses, purchased from the Argentinean market (domestic and imported products) were comparatively examined. Isolates were investigated for their ability to grow at different temperatures, pH values and concentration of NaCl, as well as for their proteolytic and lipolytic activities, respectively. The potential of these strains to produce roquefortin C in vitro, and the actual levels of roquefortin C in 10 of these cheeses were analysed by TLC. All strains showed similar growth properties in aspects of salt concentration and pH-value of the medium, and all grew well at 10 ºC. Only four strains showed proteolytic activity on casein agar, while all strains were lipolytic on trybutirin agar. After incubation at 25 ºC for 16 days, all strains produced roquefortin C in Yeast Extract Sucrose (25.6 – 426.7 mg/g) and in reconstituted (10%) sterile skim milk (26.9 – 488 mg/g). Roquefortin C at >0.1 mg/g was also found in 9 out of 10 analysed samples of blue-veined cheeses (8 from Argentine, 1 from Spain), with a maximum value 3.6 mg/g.  During the ripening process of blue-veined cheese, production of roquefortin seems to be unavoidable. Care should be taken to select strains with low toxin production characteristics, to minimize potential health risks. Roquefortin C production by P. roqueforti in vitro was not correlated with roquefortin C levels found in cheese.