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Control of microbial growth
Effected in two basic ways:
-

Killing microorganisms and Inhibiting microbial growth

Involves the use of: Physical/Chemical agents that kill or prevent growth
Principles of microbial control
-

Prevention → Control of growth to prevent infection

-

Sterilization → Complete destruction
- No ‘levels’ of sterilization → All or Nothing
- Utilizes; Heat, Radiation, Some chemicals and Physical removal

Disinfection → reducing growth on non-living surfaces
-

(Organic matter interferes with heat treatments and chemical control agents)

Antisepsis → reducing growth on living tissue
Physical Methods
Heat

Most frequent and widely used
1
...
Time of Application
3
...
Fresh or cooked foods are flash frozen
2
...
Foods are sealed in moisture and oxygen free packaging
4
...
s
...
for 30 min kills everything

Moist Heat, Pasteurization

Denatures proteins

Kills pathogens in food products

Dry Heat, Flaming

Incineration of contaminants

Used for inoculating loop

Dry Heat, Hot air oven

Oxidation & Denatures proteins

170°C for 2 hours; Used for glassware & instrument sterilization

Filtration

Separation of bacteria from liquid
(HEPA: from air)

Used for heat sensitive liquids

Cold, Lyophilization (also
desiccation)

Desiccation and low temperature

Used for food & drug preservation; Does not necessarily kill so
used for Long-term storage of bacterial cultures

Cold, Refrigeration

Decreased chemical reaction rate

Bacteriostatic

Osmotic Pressure,
Addition of salt or sugar

Plasmolysis of contaminants

Used in food preservati

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