User Manual MKA 500 / MKA 800
Conforms to
Issue 21.02.2023_01 Page 16
4.6.1 Delta temperature (Delta-T process)
Cooking with the Delta-T process (Delta temperature control) allows you to heat the product
gently and evenly. When using this process the chamber temperature is always kept higher, by
the nominal Delta value, than the actual core temperature of the product. This means the
temperature difference between the surface and the core of the product always remains constant.
The pre-set nominal temperature value is used as an upper limit value for temperature control.
A lower nominal Delta value will prolong the duration of the cooking process and the heating
process is gentler, a higher nominal Delta value will speed up the cooking process.
Hint
Apart from a nominal temperature value and a nominal Delta value, you can also enter a
nominal core value, which will be used as core shut-down condition for the step.
4.6.2 FC value
Hint
Bacteria have to be killed through pasteurisation (FC70) / sterilisation (FC121). How
thoroughly the bacteria are killed depends on the temperature and the length of time this
temperature is maintained. A mathematical formula can be applied to this process. The
degree to which the bacteria are killed is called FC value.
The process:
It is the aim of
sterilisation
to kill
all the bacteria and their spores. How thoroughly the
bacteria are killed depends on the temperature and the length of time this temperature is
maintained. A mathematical formula can be applied to this process.
(
)
(
)
=
−
−
te
Samplingra
F
Value
z
mperature
eferencete
r
T
ature
coretemper
ref
60
10
The degree to which the bacteria are killed is called F-value.
For meat cans F-value 1 means the bacteria extermination which is achieved at a core
temperature of 121,1°C, when maintained for one minute. How thoroughly the bacteria are
killed also depends on the acidity of the conserved product. Acidic conserves, fruit juices,
pickled gherkins etc have a higher killing rate and therefore a different FC value table than
normal meat conserves with a PH value between 5 and 7.
In order to avoid confusion, two further indicators can be added to the F-value, e.g. FC 121-
10 (z-value), this means that at a core temperature of 121,1°C and a time of one minute, the
F-value = 1. If the temperature is increased by 10°C, the F-value increases 10-fold.
Example of FC-value 121:
Example FC-value 70:
(
)
−
=
10
1
.
121
10
121
C
ature
coretemper
T
FC
(
)
−
=
10
70
10
70
C
ature
coretemper
T
FC
Hint
Depending on the setting, the nominal FC value is shown as displayed below.
▪
FC70 (pasteurisation), see example FC value 70
▪
FC121
(
sterilisation), see example FC value121
.
▪
FC-UD, user defined settings
Be aware
Shut-down condition:
When the pre-programmed FC-value has been reached, the controller will automatically
switch into the next step or terminate the program, respectively.
