Fungal growth and mycotoxigenic production in certain medicinal herbs subjected to prolonged cold storage and possible control by gamma irradiation

ABSTRACT

Twenty-four samples representing four kinds of medicinal herbs; namely, caraway, khella, shih balady and wild chamomile, were exposed to increasing doses of gamma radiation [from 0 to 0.5 kGy]. The sublethal doses ranged from 0.5 to 3.0 kGy. Five fungal isolates from the irradiated herb samples could produced aflatoxins and one isolate could produce ochratoxin B. The isolated fungi were identified as Aspergillus species. The herb samples were stored for two years at 5 +/- 1C and then exposed to increasing dose levels of gamma radiation. One fungal isolate from the stored khella identified as Aspergillus flavus and was confirmed for aflatoxins B1 and B2 production. The D10-value of the tested Asp. flavus isolate was 0.5 kGy