Food Micro-- Molds

Aspergillus

- many are xerophilic

- some produce mycotoxins: Aspergillus flavus; Aspergillus parasiticus (both produce AFLATOXINS)

Some species used in food processing: Aspergillus oryzae → alpha - amylase; Aspergillus niger make citric acid from sucrose (50%) in beet molassess

Alternaria

- cross and longitudinal septa on conidia

- cause brown and black rot of fruits and tubers

Geotrichum

• rectangular arthrospores

• called “machinery mold” or “dairy mold”

• grows on food-contact equipment (eg. tomato canning equipment)

• grows on dairy products -eg. cheeses

• imparts flavor and aroma to many cheeses

Cladosporium

• branched conidiophore

• dark tree-like budding conidia

• “black spot” on country-style hams and

  frozen beef, pork, veal, and lamb

• spoilage of butter and margarine

Botyritis

• long stiff conidiophores (branched at ends)

• gray rot of apples, grapes, pears, citrus, raspberries, strawberries, and blueberries

Fusarium

- sickle-shaped multicellular conidia

- brown rot of citrus fruits, pineapple, potatoes

- produce fumonisins in food grains (eg. corn)

- considered human pathogen

Rhizopus

- non-septate hyphae with rhizoids and stonons

- Rhizopus stolonifer: common bread mold

- Rhizopus oligosporus and Rhizopus oryzae: Used in production tempeh and bongkrek; watery soft rot of apples, pears, grapes, figs

Mucor

- common on saccharine and starchy foods

- “whiskers” on stored meats

- some used in rennet production: Mucor pusillus, Mucor miehei

Thamnidium

- “whiskers”; sometimes found on stored eggs

- grows on refrigerated beef hind quarters

- Thamnidium elegans – only known species

Byssochlamys

• Yeast-like mold

• produce clusters of acsi which create ascospores (which are very heat resistants!)

• Byssochlamys fulva: Thermal D-value @ 90 degrees C is 1-12 minutes (high D-value)

• Some species produce pectinases

• Uniquely associated with fruit spolage

• Spoilage of high acid canned foods, canned and bottled fruit, fruit juices, and drinks

• Try to prevent it by reducing the headspace

Penicillium

• blue-green brush-like conidia head

• spoilage of fruits, vegetables, grains, bread, and meat

• used in production of special cheeses

  (eg. blue cheese such as: Roquefort cheese (Penicillium roqueforti), Camembert cheese (Penicillium camemberti)