Hi Stella,
I've encountered this situation before. From a purely mathematical
standpoint, since 1 gram of water is equivalent to 1 ml and occupies 1
cubic centimeter (cm3) of space, the conversion factor would be the
square root of CFU/cm2 then cubed (or conversely the cube root of CFU/g
then squared). However, I have not seen a peer-reviewed manuscript that
has done the laboratory study to prove this conversion of three
dimensions to two with regards to bacterial counts is valid
statistically. Also, there are some other considerations beyond just
the mathematics such as differences between the bacterial population
surviving on a variety of food contact surfaces versus the bacterial
population proliferating in the specific types of foods in question.
Anyways, give it a go and see if the number crunching makes sense.
Regards,
Brian Himelbloom
Assoc. Prof. Seafood Microbiology
University of Alaska Fairbanks
School of Fisheries and Ocean Sciences
Fishery Industrial Technology Center
118 Trident Way
Kodiak, AK 99615-7401
Stella Stacey wrote:
>Dear List
>
>I am going to be validating a cleaning and sanitation programme and as
>part of this will be taking contact slides (press plates) of dirty
>surfaces prior to cleaning. The average of the dirty surface counts
>(CFU/cm2) should not be greater than the expected (allowed) average APC
>count for the product.
>
>I need some help with being able to make a comparison of a CFU/cm2
>count and a APC/g count as I am sure there must be some conversion
>factor when comparing results from a cm2 to /g.
>
>NOTE: These will be translated into log10 counts first.
>
>Thankyou for your assistance.
>
>Regards,
>
>Stella
>
>Stella Stacey
>Quality Manager
>Independent Fisheries Limited
>Phone: +64 3384 2344
>Fax: +64 3384 4650
>E-mail: stella.stacey@indfish.co.nz
>
>
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