Abstract
Two forms of powdery sample for tabletting were prepared ; one was the mixture of Avicell (crystalline cellulose) and freeze-dried skim milk containing Escherichia coli cells and the other was a freeze-dried powder of skim milk solution containing E. coli cells together with Avicell. E. coli cells were killed by tabletting to some extent depending on the pressure applied. Different patterns of surviving fraction/pressure relation were obtained for the above two forms of samples. Effects of temperature and moisture content of samples were also examined. Large microbial cells, such as Rhodotorula glutinis, were much more sensitive to tabletting than smaller E. coli cells. Spores of Bacillus subtilis were highly sensitive to tabletting. From these observations the major cause of killing action in the process of tabletting was considered to be the shearing force.
