http://www.icef11.org/content/papers/aft/AFT1234.pdfTransient mass and heat transfer during potato deep fat frying
–
The effect of the oil type, frying load and initial frying temperature
John S. Lioumbas,
Margaritis Kostoglou,
Thodoris D. Karapantsios
*
CONCLUSIONThe present experimental data demonstrate
that during deep fat frying, the amount of the evaporated water
and the temperature distribution inside the oil and the potato, depend strongly on the initial oil bulk
temperature and the frying load but not on the type of the oil. Specifically, higher initial oil temperatures and
lower frying loads result in increased oil temperature profiles which in turn result to higher vapour fluxes and
to final products with decreased moisture content. Moreover, the experimental results reveal that:
•
The surface water evaporation, observed on the early stages of frying, is significant for the vapour flux
time profiles behavior and for the quality of the final product as well.
•
As higher the oil temperature profile is, the higher the vapour flux rate gets.
The increased vapour flux
values should be associated with a rigid, crispy and thick crust. On the other hand, low vapour flux
values should be related with a not so intensive formation of a thin and soft crust.•
During the last minutes of frying, the vapour flux receives common values regardless of the frying
conditions,
which indicates that the phase change in a partially dehydrated zone is the dominant
mechanism of vapour generation as the frying proceeds.Moreover,a simple analytical quasi
-
state model which is
based on the assumption of a sharp moving
interface can be applied for rough estimation of the boiling heat transfer coefficient only during the higher oil
temperatures (i.e. larger than 140
o
C).
The novel experimental data presented in this study, are expected to
contribute to a better understanding of the mechanisms prevailing during deep fat frying and to contribute to
more energy-
efficient frying appliances design.
ACKNOWLEDGEMENTS
We are thankful to European Space Agency for the financial support prov
ided through the project “Influence of gravity conditions on mass and heat transfer in porous media” (ESA
-
22470/09/NL/CBi).
