1. Yeasts and Molds

2. Ferments fructose, sucrose
Resistant to many organic acids
pH 2.5
Anaerobic environments
Can produce H2S, acetic acid, esters (fruity)
Other acidic foods, such as wine

3. Mycology Study of fungi Concerns to food industry Molds Yeasts
Mushrooms
Slime molds
Puffballs…..
Concerns to food industry
Spoilage
Fermentation (foods, antibiotics, enzymes)
Mycotoxins
Food Allergies

4. Major mold genera Aspergillus Penicillium Fusarium Alternaria Mucor
Rhizopus
Cladosporium

5. General characteristics
Temperatures:
Optimal: 25-30C (Penicillium), 30-40C (Aspergillus)
Max: 28-35C (Penicillium), 37-45C (Aspergillus)
Water activity
Mid 0.7’s to mid 0.8’s required for most
Xerophilic/osmophilic fungi down to 0.6 pH
As low as 2
pH<4.0, fungi predominate in foods over bacteria
Air
Molds generally aerobic
Some can grow down to 0.1% oxygen
Distribution – widespread, but grains common

6. Exospore

7. Aspergillus flavus in peanut meal
First experimentally confirmed and characterized “mycotoxin”
Specifically called an “aflatoxin”

8. Alfatoxins Aflatoxin B1 and B2 (A. flavus, A. parasiticus, A. nominus)
Aflatoxin B1 and B2 (A. flavus, A. parasiticus, A. nominus)
Aflatoxin G1 and G2 (A. parasiticus, A. nominus)
B & G = colors
Cirrhosis, liver cancer, teratogenic, immunosuppressive
Mohamed et al., Lett. Appl. Microbiol. 2013

9. Compliance policy guidelines (CPG)

10. CPG
“The FDA program activity involving aflatoxin in domestic peanut products is directed toward products intended for direct consumption and not raw peanut products. The USDA has a comprehensive program involving raw peanuts which can be expected to result in proper processing or destruction of any high aflatoxin raw peanuts.”
“The FDA offers no objection to the shipment of peanuts over the 25 ppb level for aflatoxin to processors if facilities are available to remove moldy or otherwise defective nuts from the lot before incorporation into the finished product.”
“Recommend legal action where the following conditions are met:
Original and check analysis shows aflatoxin above 20 mg/kg;
&
Identity of aflatoxin B1 is confirmed by chemical derivative.”

11. Aspergillus control Screening nuts, grains, or seeds under UV light
Corn, peanuts, cottonseed most common
In plant: removal of contaminated raw ingredients (visual)
Storage: control moisture, low temperature, use insecticides
aw ~ 0.8 for growth, but ~0.85 for toxin production
In field: use of fungicides, development of fungal resistant varieties, biocontrol agents
Removal of mycotoxins: hydrogen peroxide, anhydrous ammonia
Aspergillus oryzae (soy sauce)

12. Patulin Penicillium expansum (fruit pathogen)
Aspergillus and Byssochylamys as well
Rotting fruits, ~ mg/L (ppb)
Survives pasteurization
CPG has limit of 50 ppb in:
Single strength apple juice (itself or as ingredient)
Reconstituted single strength apple juice
Long term health effects still unknown
Picture from:

13. On the lookout: Ochratoxin A Fumonisin FB1, FB2, FB3
Aspergillus and Penicillium species
Corn, barley, wheat, oats
Possible human carcinogen, suggested to be toxic to kidneys (in pigs as well)
Scandinavia, central Europe, western Canada
Fumonisin FB1, FB2, FB3
Fusarium verticillioides
Epi link with esophageal cancer; death in horses and pigs
Mainly corn and corn products (corn meal, breakfast cereals)
FDA advisory levels (opposed to action level): 2-4 ppb in these products

14. On the lookout (con’t):
Deoxynivalenol (DON; vomitoxin)
Fusarium sp. especially graminearum
Wheat, corn, barley, rye
Human impact unclear
Poor appetite and weight loss in animals
FDA advisory levels 1 ppm (grains for human consumption) and 5-30 ppm in grains for animals (species dependent)