The C-value describes thesurface boiling damage of a product. If the temperature at the surface of a productis higher than the core temperature, this has a negative effect on the naturalquality such as jelly heel or vitamin degradation. This C-value is calculatedon the basis of a temperature curve.
The increase in core temperature is much slower compared to room temperature. This can be explained by the different thermal conductivity values of the room air and the product. It is therefore rather suboptimal to run a cooking process with a single temperature value for the room temperature if the core temperature shows a very slow increase.
In other words, it has disadvantages if an ambient temperature of 75 degrees is maintained at an initial core temperature of 12 degrees Celsius, if no drastically faster increase in the core temperature is achieved than with clearly lower values. On the one hand, this is energy-technically inefficient, and the harmful influence of the high ambient temperatures on the food to be cooked can be just as problematic. These influences affect, among other things, the natural quality, such as jelly sales or vitamin degradation. These effects, summarized under the term “cooking damage”, are expressed in a specially created comparative value, the C-value.
This C-value is also calculated based on a temperature curve. The room temperature is used for this purpose. The calculation is done analogously to the F-value, also from and up to 55 degrees Celsius, but with other individual values, as shown in the table below.
Each time after this temperature has been reached, a corresponding C-value is obtained per unit time of one minute. The C-value for the cooking damage is based on thefollowing values:
Initial reading: 55 Grad Celsius
Reference temperature: 100 Grad Celsius
Value: 38 (value for the time-temperature dependency of the cooking)
The C-values, unlike the F-values, only increase tenfold every 38 degrees.
Similarly, the table shows that it is not ideal to work with unnecessarily high temperatures with regard to cooking damage. If we assume, for example, that a product is to be brought to 65 degrees Celsius and this is achieved in 10 hours, whether we work at 78 degrees or 70 degrees room temperature, the following two C-values result:
At 10 hourswith 70 degrees Celsius = 600 x 0,162 = C 97,2
At 10 hourswith 78 degrees Celsius = 600 x 0,264 = C 158,4
The optimal C-value cannot be quantified directly like the F-value. Rather, the cooking process should be designed so that the C-value is as low as possible. Based on the various considerations, it can be stated that a cooking process fulfills the following criteria:
· Reaching an ideal final F-value
· In terms of energy use, the room temperature must be constantly adjusted to the absolute minimum level required.
· Avoid cooking damage with a C-value that is as low as possible.
