Formation of Aflatoxin in Cheddar Cheese by Aspergillus flavus and Aspergillus parasiticus

Abstract

Three-month old Cheddar cheeses were inoculated on one freshly cut surface with spore suspensions of Aspergillus flavus or Aspergillus parasiticus (toxigenic strains) and incubated at room temperature. Cheeses were sampled after 10 and 52 days of incubation and samples were examined by thin-layer chro-matographic procedures for their content of aflatoxins B1 and G1. When A. flavus served as the test organism, the mold mycelium, top 0.64-cm layer of cheese, and second 0.64-cm layer of cheese contained 49,600, 2,900 and 4.8 [mu]g toxin B1 per kg, respectively, and 49,600, 14,400 and 9.6 [mu]g toxin G1 per kg. After 52 days of incubation the contents of B1 and G1 toxins in samples (same sequence as above) were 7,700, 1,960 and 120 [mu]g/kg. A. parasiticus, after 10 days of incubation, produced 9,780, 2,930 and less than 9.6 [mu]g toxin B1 and 48,900, 7,340 and 9.6 [mu] toxin G1 per kg of sample in the sequence listed above. Forty-two days later, the content of B1 and G1 toxins, each, in a similar series of samples was 35,000, 15,600 ana 312 [mu]g per kg. No aflatoxin was detected in cheese more than 1.3 cm from the surface.