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What Microorganisms need to Grow
Transcript of What Microorganisms need to Grow
Food must be handled very carefully when it is thawed, cooked, cooled, and reheated, as it is exposed to the temperature DANGER ZONE during these times!
Potentially Hazardous Food
Food borne microorganisms need nutrients to grow--specifically carbohydrates and proteins.
These are commonly found in potentially hazardous food, such as:
pH is a measurement of how acidic or alkaline a food is. the pH scale ranges from 0.0 to 14.0
food with a pH between 0.0 and 6.9 is acidic, while food with a pH between 7.1 and 14.0 is alkaline. A pH of 7.0 is neutral.
Foodborne microorganisms typically do not grow in alkaline foods, such as crackers, or highly acidic foods, such as lemons.
They grow best in food that has a neutral of slightly acidic pH (7.5 to 4.6)
Unfortunately, the pH of most food falls into this range
foodborne microorganisms grow well between 41*F and 135*F (5* and 57*C) This range is known as the temperature DANGER ZONE.
Exposing microorganisms to temperatures outside the temp DANGER ZONE does not necessarily kill them.
Refrigeration temperatures, for example, may only slow their growth. **Some bacteria actually grow at refrigeration temperatures.
Foodborne microorganisms need sufficient time to grow. Given the right conditions, they are capable of doubling their population every 20min!
If potentially hazardous food remains in the temperature DANGER ZONE for 4 hours or longer, foodborne microorganisms can grow to levels high enough to make someone ill.
Some foodborne microorganisms require oxygen to grow while others grow when oxygen is absent.
Most foodborne microorganisms require moisture to grow. the amount of moisture available in food for this growth is called its water activity (a little w).
Cooked rice, untreated treated garlic-and-oil mixtures, and baked potatoes have been associated with certain types of bacteria that grow without oxygen
It is measured on a scale from 0.0 to 1.0, with water having a value of 1.0. Potentailly hazardous food typically has a water activity value of .85 or higher.
Milk and Milk Products
**except those treated to eliminate salmonella
Shellfish and Crustacea
like: textured soy proteins in meat alternatives
Beef Pork Lamb
Raw sprouts and sprout seeds
Heat-treated plant food
like: cooked rice, beans, and vegetables
Tofu or other Soy-protein food
Untreated garlic-and-oil mixtures