Originally Posted by Phaedrus
I chose my word a little carelessly, that's true. But let me correct the section in red: Pasteurization does not kill all pathogens. Sterilization does (eg pressure canning). Think about it; if all pathogens were killed pasteurized milk would be shelf stable. But it's not. We're aiming for a 6D reduction in bad bugs, not total elimination.
Milk is not shelf stable because it is only pasteurized which means that the heat/time applied kills 99.9% of pathogenic bacteria (in microbiology the is always uncertainty of large numbers) but not 99.9% of all microorganisms.
Unopened milk may curdle after it's expiry date and may/will taste bad but it won't make you sick because all the pathogens are killed, only nuisance/souring microbes remain. That is the purpose of pasteurization and why it is different than sterilization which means 100% kill of ALL microbes (which included pathogens by default).
This works because pathogens are more susceptible to heat than other microbes. The temp/time tables are mostly based on the heat resistance of pathogens.
When it comes to sterilization, 125C (higher than boiling water) and pressure is required to kill everything.
Edited by Luc_H - 12/18/14 at 1:22pm