How to get log reduction?

Hi, I have a dried product. I took sample for raw material and test it for coliform as my control. The reading is 884 cfu/g. Then I applied heat at 60 degree C, and took sample to test for coliform and the reading is not detected. Another is I test the TPC from my raw material and the reading 1712 cfu/g and applied heat at 60 degree C and the result was  <25 cfu/g, my question is how to get the log reduction of it. Please I need help to understand it souz I applied different temperature until I got the result i desire for my product. honestly its my first time to do this log reduction. Thank you, boging 

Hi, I have a dried product. I took sample for raw material and test it for coliform as my control. The reading is 884 cfu/g. Then I applied heat at 60 degree C, and took sample to test for coliform and the reading is not detected. Another is I test the TPC from my raw material and the reading 1712 cfu/g and applied heat at 60 degree C and the result was  <25 cfu/g, my question is how to get the log reduction of it. Please I need help to understand it souz I applied different temperature until I got the result i desire for my product. honestly its my first time to do this log reduction. Thank you, boging 

Hi boging,

1st one is unanswerable without a <X value.

2nd one see example below.

Theory

log reduction.PNG   43.36KB   2 downloads

Example

Hand Sanitiser was tested according to EN 13697 against Escherichia coli using a contact test time of 3 minutes. The control of bacteria was given as 4.02 x 10⁶ (4,020,000 CFUs). The number of CFUs remaining after 5 minutes using Enduro Hand Sanitiser was <10 and a log reduction given of >5.60, i.e. >99.9999% reduction.

Answer/Explanation

4020000/10 = 402000

Log₁₀(402000) = 5.60 (to 2 decimal.places)

(also note the > sign)

PS an online log calculator is here -

https://www.rapidtab...Calculator.html