Yeasts and Molds

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

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

Major mold genera Aspergillus Penicillium Fusarium Alternaria Mucor Rhizopus Cladosporium

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

Exospore http://www.landcareresearch.co.nz/resources/identification/algae/identification-guide/identify/guide/glossary-items/exospore

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

Alfatoxins Aflatoxin B1 and B2 (A. flavus, A. parasiticus, A. nominus) www.fao.org 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

Compliance policy guidelines (CPG)

CPG 570.375 “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.”

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)

Patulin Penicillium expansum (fruit pathogen) Aspergillus and Byssochylamys as well Rotting fruits, ~350 - 630 mg/L (ppb) Survives pasteurization CPG 510.150 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: https://katelynwillyerd.com/tag/apple-juice/

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

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)