Food Micro-- Yeasts

Saccharomyces

• ascospores; multilateral budding

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

• Saccharomyces 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

• Zygosaccharomyces 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

• Candida 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

• Torulopsis 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: Kloeckera apiculata

Trichosporon

• psychrotrophic

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

• produce lipase