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Physical and Chemical Control
Definitions
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Sterilization
Aseptic
Disinfection
Antiseptic
Degerming
Sanitation
Pasteurization
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Germicide
Bacteriocide
Bacteriostatic
Fungicide
Virucides
Microbial Death
• Death = no growth
• Constant rate (log)
Effectiveness of Antimicrobial Agents
• Environmental Factors
– Number
• Concentration
• Composition
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Organic Matter
Exposure time
Temperature
pH
• Resistance Factors
Actions of Agents
Alter Cell Membrane by Osmosis
Alter NA
• Agents
– Heat
– Chemical
– Radiation
• Results
– Mutation
– Stop protein synthesis
Alter Proteins by Denaturing
Physical Methods of Control
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Temperature
– Heat
• Boiling
• Moist/Dry
• Pasteurization
• Incineration
– Cold
• Refrigeration
• Freezing
Irradiation
– UV
– Gamma
– X-rays
– Microwave
Filtration
Drying/Desiccation
Osmotic Pressure
– High Salt concentrations
Sterilization Methods
• Heat
– Boiling
– Steam
– Incineration
• Irradiation
• Filtration
– Membranes
• Chemical
• Gas
Chemical Agents
• Purpose
– Decrease numbers
– Does not sterilize
• Types
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Antiseptics
Disinfectants
Preservatives
Antibiotics
Antiseptics
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Phenols
Bisphenols
Biguanines
Halogens
Quaterinary
Ammonium
Disinfectants
• Types
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Phenolics
Halogens
Alcohol
Heavy Metals
Aldehydes
Peroxygens
• MOA
– Oxidize
– Denature
– Disrupt membranes
Degerming
• Surfactants
• Mechanical removal
• Examples
– Soaps
– Detergents
Food Preservatives
Calcium propionate
Sodium nitrate
Antibiotics
Resistant Organisms (most  least)
• Prions  Endospores  Mycobacteria 
Protozoan Cysts  Vegetative protozoa 
Gram (-) Bacteria  Fungal spores  Viruses
without envelopes  Gram (+) Bacteria 
Viruses with envelopes.
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