Question on calculation of number of D values

You asked the wrong question: the target of your problem is not to calculate D-value but the number of D's necessary to reach the acceptable cell density.  So the initial cell density is important.

From 1000 units to 0.001 units requires 6D.

Best,

HS Kwan

From: jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj
Sent: Tuesday, May 08, 2012 1:13 PM
To: Prof. HS Kwan (School of Life Sciences)
Subject: Questions about final exam

Dear professor Kwan,

Good afternoon, today someone ask me how to calculate the D-value from the cell density, and I found that my friend's and my method is a little bit difference.

In determining D-value, if the initial cell density of that target microorganism (#) is 1000 unit, and the acceptable cell density of # is 0.001 unit, what should be the D-value calculated? 

My method is like that:D x log (1000/0.001) = 6D

My friend's method: D x log [1/(0.001)] = 3D

I found that the main problem is that do the initial cell density needed to be involved into the calculation ? 

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