      # Please explain a 6.5 log10 reduction in Salmonella in laymans terms?

microbiologysalmonella food microbiology food safety

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### #1 Iswarya

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• United Arab Emirates Posted 25 July 2020 - 10:48 AM

What does it mean to have a  6.5 log10 (6.5D) reduction in Salmonella spp. (in meat products that contain no poultry) and a 7.0 log10 (7.0D) reduction in Salmonella spp. (in meat products containing poultry).

How will you explain the above calculations in layman terms?

### #2 Charles.C

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Posted 25 July 2020 - 03:07 PM

What does it mean to have a  6.5 log10 (6.5D) reduction in Salmonella spp. (in meat products that contain no poultry) and a 7.0 log10 (7.0D) reduction in Salmonella spp. (in meat products containing poultry).

How will you explain the above calculations in layman terms?

Hi iswarya,

The math presentation is a bit mixed up.

I think you are asking meaning of (a) a reduction of 6.5 Log and (b) a reduction of 7 Log where logarithms of base 10 are involved.

I hope link below can explain the calculation OK for you, but you will also need a calculator (or PC) for (a)  -

https://microchemlab...crobial-testing

you can probably deduce from link that -

(b) reduction of 7Log = 99.99999% reduction

(a) reduction of 6.5 Log = a %reduction  somewhere between 99.9999% and 99.99999% The exact answer needs a calculator (or excel)  and is given by the formula in above link -

P = (1-10-L) x 100  where P = % reduction and L = log reduction, ie 6.5

So required calculation is P = (1-10-6.5) x 100

I don't have a calculator with me so maybe someone else can do it.

(I think you already know that 6.5D = (numerically) a reduction of 6.5Log etc )

IF above is bit math-heavy for you, an explanation in more bacterial terms is here -

https://www.enduroci...inners-guide-2/

Kind Regards,

Charles.C

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### #3 Ryan M.

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Posted 29 July 2020 - 02:29 PM

Just picture a "log 10" as one zero in a number.

Log 1 = 10

Log 2 = 100

Log 3 = 1,000

Log 4 = 10,000

Log 5 = 100,000

Log 6 = 1,000,000

Log 7 = 10,000,000

So log 6.5 is roughly somewhere between 1,000,000 to 10,000,000 salmonella reduced after the cook or other "kill" step.

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### #4 Charles.C

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Posted 29 July 2020 - 10:11 PM

Just picture a "log 10" as one zero in a number.

Log 1 = 10

Log 2 = 100

Log 3 = 1,000

Log 4 = 10,000

Log 5 = 100,000

Log 6 = 1,000,000

Log 7 = 10,000,000

So log 6.5 is roughly somewhere between 1,000,000 to 10,000,000 salmonella reduced after the cook or other "kill" step.

Sorry but the above is numerically incorrect.

For example, -

Log1 = Log10 (1) = 0

and -

Mathematically -

logb(x) = y exactly if by = x and x >0 and b > 0 and b not = 1

for example, log2 64 = 6, as 26 = 64.

Similarly 100 = 1

The difficulty derives from the fact that "1 Log" does not equal "Log10(1)"

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Kind Regards,

Charles.C

### #5 Ryan M.

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Posted 29 July 2020 - 10:20 PM

Woops...you are right.  Thanks for setting me straight.  I was thinking in terms of log reduction; not log10.

Sorry but the above is numerically incorrect.

For example, -

Log10 (1) = 0

and - logarithms.PNG

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