• Microorganisms are sensitive to heat and are killed at certain temperatures, which may be below or, in the case of spore forming microorganisms, above 100°C (see also box below).
• Each species of microorganisms reacts differently to heat treatment, due to their different heat resistance.
• Microorganisms are quickly killed when they are exposed to relatively high temperatures.
• Microorganisms can also be killed at relatively low hot temperatures, but longer heat treatment periods will be necessary in such cases.