Tyndallisation is a method of -
A single exposure of 90 minutes usually ensures sterilization but for media containing sugars or gelatin, an exposure of 100-degree Celsius for 20 minutes on 3 successive days is used. This is known as tyndallisation or intermittent sterilization REF:Ananthanarayan and Panicker's Textbook ofMicrobiology 8thEdition pg no:32
Growing bac teria in pure culture
Sterilization
Inoculation of media
Preserving cultures
general microbiology