Chapter 9 Lecture 3
Physical methods of Microbial control
exposure to extreme heat or cold
desiccation
filtration
osmotic pressure
radiation
heat related methods
denature proteins
interfere with integrity of cytoplasmic membrane and cell wall
disrupt structure and function of nucleic acids
heat can be used for sterilization
microorganisms vary in their susceptability
Moist Heat
commonly used to disinfect, sanitize, sterilize, pasteurize, cells by denaturing proteins and destroying the cytoplasmic membrane
more effective than dry heat
methods of microbial control using moist heat
boiling
autoclaving
pasteurization
ultra high temp sterilization
boiling
kills vegetative cells of bacteria and fungi, protozoan trophozoites, and most viruses within 10 minutes at sea level
different elevations require different boiling temps
autoclaving
higher temp than boiling
kills all microbes
Pasteurization
moist heat
milk, ice cream, yogurt, fruit juice
Dry heat
hot air denatures proteins and promotes corrosion