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11 Cards in this Set
- Front
- Back
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bacteria
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-exist in vegetative state
-some are spore forming helps bacteria survive when environment is too hot, cold, dry, acidic, not enough food -germinated -spore can return to vegetative state and begin to grow again |
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spoilage and disease-causing bacteria
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Spoilage bacteria
-breakdown of foods- rarely cause sickness Pathogenic bacteria -disease causing microorganisms |
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factors that contribute to bacteria growth
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-FAT TOM
-food/energy acid/pH -time -temp -oxygen -moisture/water |
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Phases of bacterial growth
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lag phase:
first few hours little or no growth log phase; very rapid growth, doubling every few min. stationary phase - #'s produced = #'s dying off -decline phase: -die off rapidly ( lack of nutrients, poisoned by own waste ) |
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FAT TOM- water
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water activity
-disease causing live in .85-1 -lowering water activity helps with food preservation |
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Food source
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preferred food supply is high in proteins or carbs
-water activity of proteins and carbs are high |
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oxygen
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aerobic bacteria:
anaerobic bacteria Facultative anaerobic forms of bacteria: -can grow with or without free oxygen, usually have a preference * most disease causing organisms grow wellin canned food, vacuum packaged, center of big good masses/ large stock pots, large roast |
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pH
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- designates acidity or alkalinity
- most foods are acidicd - food < 4.6 will not support the growht of diseae causing bacteria ex: pickling |
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pH examples
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Alkaline (> 7)
egg whites, olives, soda crackers Neutral ( most preferred) Disease causing grow best in pH of 4.6-7 milk, meat, fish |
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temperature
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-most grow with in 41-135 F
Psychrophillic bacteria: grow with 32-70F ; spoilage organism Mesophilic bacteria 70-110F ( human body temp) Thermophillic bacteria above 110F -spoilage organisms |
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Time
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-idea conditdions- can double every 15-30 min.
-4 hrs in danger zone is enough time for bacteria to multiply to high enough numbers to cause illness |
