RESUMEN
Forty-two random samples of Karish cheese were collected and analyzed for mycotoxins and the effect of gamma irradiation on growth and production of mycotoxins by toxigenic stains of Penicillium in Karish cheese was studied. Of the 42 samples only 2 [4.7%] were positive for ochratoxin A and all samples were negative for aflatoxin, penicillic acid, citrinin and cyclopiazonic acid. In addition of 108 cultures of Penicillium spp. And Aspergillus spp. Only 23 were positive for cyclopiazonic acid, 13 for aflatoxin B1, 9 for ochratoxin A, 8 for penicillic acid, and 4 for citrinin. Cheese samples were inoculated with conidia of P. viridicatum, P. cyclopium and P. chrysogenum and then irradiated at a dose of 1.5 and 3.5 kGy and incubated for prolonged period at 25C of colony-forming units was lower than the unirradiated controls. Ochratoxin A, cyclopiazonic acid and penicillic acid production by P. viridicatum, P. cyclopium and P. chrysogenum decreased from the control level with increased dose and were not detected at 4.0 kGy