1. PHYSICAL METHODS FOR KILLING MICROBES
Sterilization methods
Incineration
Autoclave
Dry heat oven
Filter sterilization
Ultra violet light
Gamma radiation

2. The direct flame represents a rapid sterilization method
Incineration

3. The autoclave uses moist heat and pressure

4. Boiling water involves moist heat
This is not a reliable method for sterilization unless tyndallization is used.
Why not?

5. Pasteurization does not sterilize
It is used to kill unwanted or harmful microbes
Why doesn’t it sterilize?

6. Hot-air (dry-heat) oven
Time and Temperature: 338F for 11/2 hours

7. Filter Sterilization

8. Filtration traps microorganisms

9. Ultraviolet light can be used to control microbial growth
UV light attacks the cell’s DNA
What are some disadvantages in the use of UV for sterilization?

10. The Ionizing and Electromagnetic Spectrum of Energies

11. Thymine Dimers of DNA form when exposed to UV light

12. Thymine Dimers

13. CHECK MOLES FOR THESE CHANGES

14. GAMMA RADIATION
A widely used method for sterilizing materials that would be adversely altered by heat (plastics, lensed equip. heart-lung machines etc).

15. Logo for gamma radiation
Look for this logo on those foods that have been treated with gamma radiation, such as meats, and produce.

16. PRESERVATION METHODS Drying (dehydration) Method Salting Method
Low pH Method
Do these methods sterilize the food? Explain.

17. General Principles of Chemical Control

18. Resistance of microbes to chemical agents

19. Disinfectants

20. Killing Action of certain metals

21. Killing Action of Some Antiseptics