How to calculate The Least Sterilizing Value (F0) for Water Activity?
Hi Garnet,
Not too sure about the Title. Water activity ? :smile: (But see PS below!)
As I understand, the “least sterilizing value (LSV)”, is typically determined by a so-called “Expert Authority” for the purposes of processors registering their process, eg with FDA.
The EA apparently makes this decision based on heat penetration data as supplied by the processor and knowledge / experience of the product/system to be used.
Unfortunately I have found specific definitions for LSV elusive. The only one I could find was –
Fo (LEAST STERILIZING VALUE) The number of minutes at a reference temperature of 250 degrees Fahrenheit required to kill a known population of microorganisms with a z value of 18 degrees Fahrenheit. This value must be obtained from a scientifically qualified process authority
afaik sterilization processes for Low-acid products usually involve 2 contributory factors to the overall required lethality value – (a) a safety contribution based on a 12D reduction of any existing C.botulinum (typically set at F0 =3) and (b) a non-safety component to ensure commercial sterility.
It is unclear to me if the LSV includes (a+b) or only refers to (a).
The data for LSV in the attached example below rather implies (a,b) but is not definitive. If it does include (b) the determination looks non-simple.
Maybe you, or any canning/pouching people here, can clarify ?
Principles-of-Thermal-Processing,2005.pdf 95.18KB 90 downloads
PS - Just realized the possible significance of yr titling water activity ! -
Thank you!!
I appreciate to your prompt reply.
seems like I should study more. :)
Thank you for your help again.