← Chapter 8 · Controlling Microbes
Microbiology · Chapter 8

Physical Methods of Control

Some microbes shrug off chemicals, and some products would be ruined by them. Physical methods reach for heat, pressure, radiation, and barriers instead, and they leave no chemical behind. Four working models sit below. Set the dials and watch what lives.

Moist heat versus dry heatmove the dials

Heat denatures proteins and wrecks membranes. Steam does it far faster than hot air.

Four physical methodspick one and set the dials
Temperature 100 °C
Time held 10 min
Vegetative cells0
Endospores0
D-value now188 min
Verdictnot enough
Load
How the air leaves the chamber
Hold time at temperature 15 min
Chamberready
Gauge pressure0 psi
Spore logs killed0
Spore vialnot run
Kind of radiation
What sits between the source and the microbes
Energy arriving100%
Logs killed>12
Sterilizes?yes
Membrane pore size
Held back0 of 7
Got through0 of 7