Concept of PNSU

• PNSU - probability of a non-sterile unit

• Establishes a target end point for the lethal treatment (i.e., 1 out of 10^-6 non-sterile units)

• Pflug* recommended end points of:

  • public health end point of 10^-9 for C. bot
  • mesophilic spoilage end point of 10^-6
  • thermophilic spoilage end point of 10^-3 for low temperature storage or 10^-6 for high temperature storage

*Pflug, 1987, Endpoint of a preservation process, J. of Food Protection, Vol 50, 347-351