| Molds: general | - filamentus fungi
- aerobic
- can grow in low MC/pH, high sugar/acid/salt
- produce aerial and subsurface hyphae
- some produce mycotoxins
- many can grow at 41F or lower
- most produce spores |
| Mold hyphae | - septate or non-septate cross walls |
| Mold spores | - formed on aerial hyphae
- transported by air, water, humans
- germinate to form new mold
- survives freezing |
| Aspergillus | - mold genera
- septate hyphae; conidia in chains
- yellow, green, or black growth on foods
- many are xerophilic
- some produce mycotoxins (Aspergillus flavus and parasiticus)
- used in food processing (Aspergillus oryzae)
- Aspergillus niger produces citric acid from sucrose in beet molasses |
| Aspergillus example | - Aspergillus flavus, Aspergillus parasiticus: both produce aflatoxins - Aspergillus oryzae: amylase - Aspergillus niger: make citric acid from sucrose (50%) in beet molassess |
| Alternaria | - mold genera with septate hyphae
- large ovate or club-shaped conidia in chains --> unique shape
- cross and longitudinal septa on conidia
- grow on fruits, grain, red meats, and dairy products
- cause brown and black rot of fruits and tubers |
| Geotrichum | - mold genera with septate hyphae
- rectangular arthrospores
- hyphae dichotomously branched
- called machinery old or dairy mold
- grows on food-contact equipment and dairy products
- imparts flavor and aroma to many cheeses |
| Geotrichum example | Geotrichum candidum: grows on rind of Gouda cheese |
| Penicillium | - mold genera with septate hyphae
- blue green brush-like conidia head !!
- spoilage of fruits, vegetables, grains, bread, and meat
- used in production of special cheeses |
| Penicillium | - Penicillin um roqueforti: Roquefort cheese - Penicillium camemberti: Camembert cheese |
| Cladosporium | - spoilage of butter and margarine
- mold genera with septate hyphae
- branched conidiophore
- dark tree-like budding conidia
-ovate conidia; 2 celled when mature
- black spot on meat products
-produces lypases to break down fats |
| Botyritis | - mold genera with septate hyphae
- long stiff conidiophores (branched at ends)
- small ovate conida in grape-like bunches
- causes gray rot of apples, grapes, pears, citrus, raspberries, strawberries, and blueberries |
| Fusarium | - sickle-shaped multicellular conidia
- non-septate hyphae, mold genera
- cotton mycelium (loose growth)
- pink, red, purple, or brown |
| Rhizopus | - non septate hyphae with rhizoids and stolons
- mold genera
- sporangiophores in clusters
- common on saccharine and starchy foods
- bread mold, fermentation of food, watery soft rot |
| Mucor | - non septate hyphae; simple mold genera
- some species used in rennet production
- columella; globular sporangia
- common on saccharine and starchy foods |
| Thamnidum | - 'whiskers', sometimes found on stored eggs
- non-septate hyphae mold genera
- small sporangia on branched structures
- Thamnidium elegans: only known species |
| Byssochlamys | - yeast-like mold
- produces clusters of asci
- each ascus has 8 ascospores
- some species produce pectinases (fruit juice separation)
- uniquely associated with fruit spoilage |
