Food Micro Molds and Yeasts for Exam 1

Saccharomyces

• ascospores; multilateral budding

• __________ cerevisiae used in: baking (leavening of bread), beer and wine production

• ___________ bailii spoils tomato sauce, mayonnaise, salad dressing, soft drinks, fruit juices, ciders, and wines

Schizosaccharomyces

• likes acid conditions

• can spoil honey (but take years because of honey’s low water activity)

• osmophilic

• growth in high sugar conditions

• resistant to some chemical preservatives

Zygosaccharomyces

• osmophilic

• ________________ rouxii can grow at aw of 0.62

• some species involved in: shoyu and miso fermentation

Pichia

• ascospores shaped like derby hats

• spoils alcoholic liquors, sauerkraut,

  pickles

• can grow in olive brine

• some found on fresh fish and shrimp

Debaromyces

• growth in 24% NaCl; at aw of 0.65

• common in dairy products

• spoilage of cheese, yogurt, pickles, wines, cured meats, orange juice concentrate

Candida

• spoilage of ground beef, poultry, cured meats

• ___________ lipolytica spoils dairy products

Rhodotorula

• pink to red yeasts

• many are psychrotrophic

• found on fresh beef, poultry, shrimp, fish

• red spots on sauerkraut

Torulopsis

• pseudomycelium

• __________ versatilis: can ferment lactose, can spoil milk, can also spoil fruit concentrates and acidic foods

Kloeckera

• apiculate (pear-shaped)

• fermentative and oxidative

• spoilage of wines, fruit and fruit juices: ___________ apiculata

Trichosporon

• psychrotrophic

• found on refrigerated beef, poultry, frozen lamb, and other refrigerated foods

• produce lipase

Aspergillus

- many are xerophilic

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

Some species used in food processing: ___________ oryzae → alpha - amylase; ____________ 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

- _______ stolonifer: common bread mold

- _______ oligosporus and ________ 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: ________ pusillus, _________ miehei

Thamnidium

- “whiskers”; sometimes found on stored eggs

- grows on refrigerated beef hind quarters

- __________ elegans – only known species

Byssochlamys

• Yeast-like mold

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

• ____________ 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)