4 replies to this topic

[nerea]

Hi all,
I have two questions.
1. What does "NPN/g"?
2. How to calculate dimention "NPN/g" into "CFU/g"?

Thanks!
Nerea

[nerea]

Hi all,
I have two questions.
1. What does "NPN/g"?
2. How to calculate dimention "NPN/g" into "CFU/g"?

Thanks!
Nerea

Sorry, I have a mistake: it isn't NPN, it is MPN

[George @ Safefood 360°]

Hi Nerea

I was just about to ask to check whether you meant MPN and not NPN. If my applied microbiology serves me well i believe it means Most Probable Number. I0 tis used for a specific testing method whereby dilutions of a sample are prepared and added to a specific reagent which produces a colour change over time when incubated at a particular temperature. This is an indicator of the most probable numbers of bacterial cells present. A calculation is conducted from the various dilutions prepared. I used it for a number of years while testing milk products for Coliforms. It does not measure directly the number of colony forming units like traditional plating methods but instead relies on a rate of a chemical reaction.


Anyway my memory is a little sketchy on this but this might be enough to get you started on researching it further. I'm sure the laboratory who is conducting the testing will provide with a more comprehensive explanation.


George

[nerea]

Hi Nerea

I was just about to ask to check whether you meant MPN and not NPN. If my applied microbiology serves me well i believe it means Most Probable Number. I0 tis used for a specific testing method whereby dilutions of a sample are prepared and added to a specific reagent which produces a colour change over time when incubated at a particular temperature. This is an indicator of the most probable numbers of bacterial cells present. A calculation is conducted from the various dilutions prepared. I used it for a number of years while testing milk products for Coliforms. It does not measure directly the number of colony forming units like traditional plating methods but instead relies on a rate of a chemical reaction.


Anyway my memory is a little sketchy on this but this might be enough to get you started on researching it further. I'm sure the laboratory who is conducting the testing will provide with a more comprehensive explanation.


George

Hi, George

Yes, I meant "MPN".
Thanks for this information, it's useful for me.

Nerea

[Charles.C]

Hi all,
I have two questions.
1. What does "NPN/g"?
2. How to calculate dimention "NPN/g" into "CFU/g"?

Thanks!
Nerea

Dear nerea,

Can try these links for CFU/g and MPN/g respectively -

http://www.fda.gov/F...M/ucm063346.htm

http://www.fda.gov/F...M/ucm109656.htm

Rgds / Charles.C