FDZ Values Flashcards
1
Q
What is D-value?
A
Decimal reduction time
Time needed to reduce the microbial population by 90%
2
Q
What is Z-value?
A
Increase in temperature required to cause a 90% reduction in D-value
3
Q
What is F-value?
A
Thermal death time
Total time needed to accomplish a reduction
4
Q
D-value equation
A
t2-t1 / logN(t1) - logN(t2)
equal to 1/slope when plotted
5
Q
Z-value equation
A
t2-t1 / logD(t1) - logD(t2)
equal to 1/slope when plotted
6
Q
F-value equation
A
F = (number of log cycles) x D
7
Q
How is D-value plotted?
A
x-axis = time
y-axis = number
8
Q
How is Z-value plotted?
A
x-axis = temperature
y-axis = D-value
9
Q
Microbial survival curve
A
logN = -kt + logN(0)
N = num of microorganisms
t = time
k = kinetic constant (slope)
10
Q
How to quantify success of preservation?
A
- quantify initial number of microorganisms
- apply external agent
- take periodic samples
- quantify number of microorganisms
