Oil partitioning between surface and structure of deep-fat fried potato slices: A kinetic study

Abstract

The present work deals with the kinetics of partitioning of oil on the surface as well as in the structure during holding of fried potato slices at elevated temperatures (100, 120, 140, 160 and 180 °C) compared with controls. After frying, the oil present on the surface migrates into structure due to condensation of vapor inside the product resulting in the creation of a vacuum. However, the oil present on the surface need not migrate into the structure, if the fried product is held at elevated temperatures. Further, the excess oil, which did not migrate into structure, can be removed by absorbent paper. The oil partition coefficient, defined as the ratio of oil present on the surface to the structure, during holding of samples at 180 °C was found to be 3.06, whereas the oil partition coefficient of the sample held at ambient temperature was 0.53, which indicates the availability of oil on the surface of fried product held at elevated temperature. The mass transfer coefficient of oil corroborated with the above finding. The holding of deep-fat fried product at 180 °C followed by the removal of oil from the surface using high absorbent paper reduced the oil content of the final product from 0.440 to 0.332 kg of oil/kg dry solids.