Chapter 7: The _______ of Microbial Growth Microorganisms and Microbial Growth Figure 7.11.
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Transcript of Chapter 7: The _______ of Microbial Growth Microorganisms and Microbial Growth Figure 7.11.
Chapter 7: The _______ of Microbial GrowthMicroorganisms and Microbial Growth
Figure 7.11
Terminology Related to the __________ Microbial Growth
• ___________: Removal of all microbial life• ___________: Removal of pathogens• __________: Removal of pathogens from living
tissue• __________: Removal of microbes from a limited
area• Sanitization: Lower microbial counts on eating
utensils• _____________________: Kills microbes• Bacteriostasis: Inhibiting, not killing, microbes
Effectiveness of antimicrobial treatment depends on:
• ______ of microbes• Environment:
Ex. temperature• ______ of exposure• Microbial
characteristics
Microbial Control Agents
______________Heat, Filtration, Low Temperature, Pressure,
Dessication, Radiation______________
Phenols, Chlorhexidine, ________, Halogens, Heavy Metals, Surface Active Agents
Various Effects of Microbial Control Agents• Alteration of membrane permeability• Damage to proteins• Damage to _____________ acids
Physical Method of Microbial Control: Moist Heat
• Moist heat denatures proteins
• Autoclave: _______ under pressure
Figure 7.2
Physical Methods of Microbial Control: Dry Heat
• Dry Heat Sterilization kills by ______________– ______________– Incineration– Hot-air sterilization
Hot-air Autoclave
Equivalent treatments 170˚C, 2 hr 121˚C, 15 min
Physical Methods of Microbial Control______________
_____________ reduces spoilage organisms and pathogens•Methods used in pasteurization:
– ____________________– High-temperature short-time 72°C for 15 sec– Ultra-high-temperature: _______________– Thermoduric organisms survive
_____Methods of Microbial Control cntd.• _____________
removes microbes
• _____________: inhibits microbial growth
– Refrigeration– Deep freezing– Lyophilization
• _________________ denatures proteins
• _________________ prevents metabolism
• _________________ causes plasmolysis
________________ damages DNA
Physical Methods of Microbial Control______________
• Radiation damages _________• Types of radiation:
– Ionizing radiation (X rays, gamma rays, ____________) – Nonionizing radiation (__) – (___________ kill by heat; not especially antimicrobial)
Chemical Methods of Microbial Control
Types of Disinfectants___________ – disrupt plasma membranesIodine, Chlorine, Bleach – _____________ agents_________ – denature proteins, dissolve lipids________________ – denature proteinsPeroxides – oxidizing agents
Principles of effective disinfection– ________________ of disinfectant– Organic matter– pH– Time
______ Methods of Microbial Control
Types of Disinfectants___________ – disrupt plasma membranesIodine, Chlorine, Bleach, Peroxides – ________ agentsAlcohols – denature proteins,
dissolve lipidsHeavy metals – denature
____________Principles of effective disinfection
– _______________ of disinfectant
– Organic matter– pH– Time
Types of Disinfectants• Surface-Active Agents or Surfactants__________ Degerming
Acid-anionic _______________ Sanitizing
Quarternary ammonium compoundsCationic detergents
Bactericidal, Denature proteins, disrupt plasma membrane
Evaluating a Disinfectant• __________________ method
FOOD PRESERVATION
• Chemical Food Preservatives– _________ Acids: sorbic acid, benzoic acid,
calcium propionateInhibit metabolism
Control molds and bacteria in foods and cosmetics
– __________: prevents endospore germination– __________: Nisin and natamycin prevent spoilage
of cheese