Using the F0 Equation to Determine an Unspecified Parameter Affecting Steam Sterilization

 

F0 in minutes =

= (D at 121°C) * (LOG10(initial organism concentration) - LOG10 (final organism concentration))

 

where:

• D is the number of minutes required to kill an organism at 121°C. Typically this is 1.0, but may range from 0.5 (susceptible) to 2.0 or more (resistant spore).

• The concentration units for the bacteria is not given. I will use CFU per mL.

 

If one of the parameters is unknown then it can be calculated by rearranging the equation.

Unknown	Expression
F0	D * (LOG10(initial concentration) - LOG10 (final concentration))
initial organism concentration	10^(LOG10(final concentration target) + (F0 / D))
final organism concentration	10^(LOG10(initial concentration target) - (F0 / D))