Set 4: Physical Control - Heat Methods

Describe the effectiveness of moist heat

• degrades enzymes

• destroys bacterial cells (vegetative) & viruses

• disrupts membranes

• destroys proteins

• destroys nucleic acids

• only disinfects, not sterilize

• Boiling for 30 mins kills vegetative cells but is NOT necessarily sterilization as spores survive

Describe the effectiveness of dry-heat

• Uses incinerators/ovens

• Less effective than moist heat

• used for powders and oils

• ruins plastics + rubber objects

At what time and temp does the dry-heat method need to be at?

at 150-180°C for 2-4 hours

How does an autoclave work?

sterilizes objects using steam + pressure

What are the specific parameters (temp/pressure/time) for an autoclave?

• minimum: 121°C

• and 15 psi for at least 20 minutes

What does the autoclave kill?

• vegetative cells

• spores

Define Pasteurization

a technique that is used for heat-sensitive liquids

What are the 2 main methods in Pasteurization?

• Flash Method: 71.6°C for 15 seconds

• Batch Method: 63-66°C for 30 minutes.