UHT Processing Calculations
Step 1: Time in hold tube
Flow rate through hold tube, Q
flow
=
gal/min
m
3
/s
Length of hold tube, L
tube
=
feet
meters
Inside diameter of hold tube, d
tube
=
inches
cm
V
max
/V
av
*
=
Hold time =
sec
Step 2: D-value at Processing temperature
Processing Temperature, T =
o
F
o
C
D-value at Reference Temperature, D
ref
=
sec
Reference Temperature, T
ref
=
o
F
o
C
Z-value =
o
F
o
C
D-value at processing temperature, D
T
=
sec
Step 3: Lethality
Total microbial reductions, Log(N/N
0
) =
See also
D and Z values in Thermal Processing of Foods