Tyndallization/Discontinuous heating

Tyndall that started thinking about finding a process that will not only kill the bacteria but also their spores during sterilization. This resulted in the development of the process of discontinuous heating which was later termed as Tyndallization. In this process organic infusions were 1st heated for few minutes to kill the bacteria present in it. Then the infusion was kept for sometime in room temperature. This would result in the germination of the spores (heat stable) of the bacteria. Then the infusion was again heated for few minutes to kill the germinated spores (not heat stable). Then again the infusion was kept at room temperature for germination of the spores still left (late germinating spores). After following this cycle for several times one could destroy all the bacteria including their spores present in the organic infusion. Tyndall optimized that boiling for 1 minute for successive 5 cycles (with rest in between) would make the infusion sterile whereas non stop boiling even for 1 hour would not have that effect. But there was a drawback in this system of sterilization as germination time & heat resistance of bacteria vary from species to species and hence one must have a thorough understanding of the bacteria present in the infusion which is very difficult.