Aflatoxin is partially or completely degraded by irradiation, heat, or treatment with strong acids or bases, oxidizing agents or bisulfite. Hydrogen peroxide plus riboflavin denature aflatoxin in milk. Mycelia of Aspergillus parasiticus can degrade aflatoxin, possibly via fungal peroxidase. Such degradation is affected by strain of A. parasiticus, amount of mycelium, temperature, pH and concentration of aflatoxin. Adsorbants, including bentonite and activated charcoal, can physically remove aflatoxin and patulin from liquid foods. Patulin is stable at low pH values but not in the presence of large amounts of vitamin C or bisulfite. Patulin can be degraded by actively fermenting yeasts and rubratoxin can be degraded by the mycelium of Penicillium rubrum.

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The ability of Listeria monocytogenes to survive the Camembert cheese-making process and grow during ripening of the cheese was examined. Pasteurized whole milk was inoculated to contain about 500 L. monocytogenes [strain Scott A, V7, California, (CA) or Ohio (OH)] CFU/ml and made into Camembert cheese according to standard procedures. All wheels of cheese were ripened at 6°C following 10 d of storage at 15–16°C to allow proper growth of Penicillium camemberti. Duplicate wedge (pie-shaped), surface and interior cheese samples were analyzed for numbers of L. monocytogenes by surface-plating appropriate dilutions made in Tryptose Broth (TB) on McBride Listeria Agar (MLA). Initial TB dilutions were stored at 3°C and surface-plated on MLA after 2, 4, 6 or 8 weeks if the organism was not quantitated in the original sample. Selected Listeria colonies from duplicate samples were confirmed biochemically. Results showed that numbers of Listeria in cheese increased 5- to 10-fold 24 h after its manufacture. Listeria counts for strains Scott A, CA and OH decreased to <10 to 100 CFU/g in all cheese samples taken during the first 18 d of ripening. In contrast, numbers of strain V7 remained unchanged during this period. All L. monocytogenes strains initiated growth in cheese after 18 d of ripening. Maximum Listeria counts of ca. 1 × 106 to 5 × 107 CFU/g were attained after 65 d of ripening. Generally, a 10- to 100-fold increase in numbers of Listeria occurred in wedge or surface as compared to interior cheese samples taken during the latter half of ripening. During this period, Listeria growth paralleled the increase in pH of the cheese during ripening.