7/23/2019 What is F0 and Why is It Important for Sterilization

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 AlthoughtheformulafordetermininganF0valueisquitescientific,thelogicbehinditcan

becomparedtoanordinarytaskthatwecanallrelateto. 

When baking brownies, the box says to bake

them at 350 °F for 35 minutes. However,

because we are sometimes impatient, the

batter is put in when the oven is only

preheated to 200 °F. So what happens while

the oven continues to ramp up the

temperature to reach 350 °F? Of course, the

brownies do not wait, and the batter partially

cooks during this time, which effects the

overall duration required and the result,

potentially under cooked or overcooked

brownies.

A similar logic applies to using an autoclave

for sterilizing medical equipment. There are

certain time and temperature thresholds that must be met in order to kill harmful organisms and achieve safe

sterilization. Sterilizing at a lower temperature increases the amount of time required, whereas the higher

temperatures will achieve sterilization much faster. The calculation for F0 in a particular application is the

formula used to ensure efficient and effective sterilization is achieved.

There are many factors that are considered such as cycle speed, efficiency and product exposure to find the

right balance for managing sterilization cycles. Over sterilizing, at high temperatures for too long, can be costly

or potentially begin to cause degradation to the devices being sterilized. Under exposure or temperatures that

are too low will not provide adequate sterilization. Depending upon the product being sterilized, there is often

an industry standard to ensure the depletion of all potentially harmful bacteria and a baseline that is used in

determining the F0 value.

Just as the brownies partially cooked before reaching 350 °F, some bacteria will be killed before the autoclave 

reaches 121 °C. To take this into account, the F0 calculation is used to show the equivalent of heating something

at a lower temperature. For instance, let's use an example product that must be held at 121 °C for 12 minutes to

achieve sterility. If the autoclave was only heated to 100 °C, it would take longer than 12 minutes to reach the

proper sterility. The F0 calculation tells users this value, so the cycle is not extended beyond what is necessary,

saving both time and energy.

With the latest release of the MadgeTech Data Logger Software, a number of sterilization units can now be

applied and displayed in graph reports. This gives users the ability to see the process of sterilization that

occurred during the entire cycle, including during the ramp up time. To learn more about this feature of the

software, watch the video here.