title: Influence of gamma-irradiation and maize lipids on the production of aflatoxin B1 by Aspergillus flavus.
abstract: The effect of gamma-irradiation and maize lipids on aflatoxin B1 production by Aspergillus flavus artificially inoculated into sterilized maize at reduced water activity (aw 0.84) was investigated. By increasing the irradiation doses the total viable population of A. flavus decreased and the fungus was completely inhibited at 3.0 kGy. The amounts of aflatoxin B1 were enhanced at irradiation dose levels 1.0 and 1.5 kGy in both full-fat maize (FM) and defatted maize (DM) media and no aflatoxin B1 production at 3.0 kGy gamma-irradiation over 45 days of storage was observed. The level in free lipids of FM decreased gradually, whereas free fatty acid values and fungal lipase activity increased markedly by increasing the storage periods. The free fatty acid values decreased by increasing the irradiation dose levels and there was a significant enhancement of fungal lipase activity at doses of 1.0 and 1.50 kGy. The ability of A. flavus to grow at aw 0.84 and produce aflatoxin B1 is related to the lipid composition of maize. The enhancement of aflatoxin B1 at low doses was correlated to the enhancement of fungal lipase activity.
authors.affiliation: National Center for Radiation Research and Technology, Microbiology Department, P.O. Box 29, Nasr City, Cairo, Egypt.
authors.forename: Nagy H
authors.initials: NH
authors.lastname: Aziz
authors.forename: Samia A
authors.initials: SA
authors.lastname: el-Zeany
authors.forename: Lotfy A A
authors.initials: LA
authors.lastname: Moussa
mesh_terms: D016604:Aflatoxin B1 / Q000096:biosynthesis* / Q000528:radiation effects; D001231:Aspergillus flavus / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D015169:Colony Count, Microbial; D004307:Dose-Response Relationship, Radiation; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005514:Food Irradiation; D005720:Gamma Rays; D008049:Lipase / Q000378:metabolism / Q000528:radiation effects; D050356:Lipid Metabolism; D013997:Time Factors; D003313:Zea mays / Q000737:chemistry* / Q000382:microbiology
chemical_list: D005230:Fatty Acids, Nonesterified; D016604:Aflatoxin B1; D008049:Lipase