III.5.4. Discussion/ Interpretation:
The Chef prefers the cooked fish filets when the temperature is between 62°C and 65°C, for 15 to
20 min. Below 62°C, the flesh is too soft, there is a lack of firmness (moreover, for temperatures below
60°C, there are safety issues). At temperature higher than 65°C, the flesh is too firm and dry, according to
Also, we can observe the green colour of the algae, which is interesting. The Chef finds some
algae savours in the flesh of the bar, and this was what he tried to obtain on the top of its cooking.
From a technical point of view, this method of cooking the fish is easy at the restaurant because
the times of cooking are between 15 and 20 min, which corresponds to the interval of time between a
command and the service of the dish. The method of cooking is known for the restaurant team. The
technique is easy to implement
III.5.5.1. Fourier’s law, statements (1) (2) :
Let us consider a volume of material which is at initial temperature T. One of a surface of this
volume is suddenly heated at a temperature T + _T.
Figure 19 : tests on a plate.
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The heat propagates from the warmest face to the coldest face by conduction. This propagation
of heat corresponds to a flow q, proportional to the temperature gradient.
· The minus sign indicates that the heat goes from the warm side to the cold one. Thus, the flow goes
to the decreasing temperatures direction (opposite sign compare to the positive pressure gradient).
· k (thermal conductivity) is a proportionality coefficient, representative of the capacity of the material to
conduct the heat.
· The unity of k is given by : [q] = W / m2 => [k] = W / m / °K = W m-1 °K-1
III.5.5.2. Application of the Fourier’s law to the cooking of bars xi xii xiii:
Jq = -k d
T x ( ) .c
We indeed have a time of cooking, depending on the temperature of the oven.
This method of measure of the cooking time is reliable, and doesn’t add any difficulties to the
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