The objective of this research was to determine the kinetics of water loss and oil uptake during frying of
pre-treated potato slices under vacuum and atmospheric pressure. Potato slices (diameter: 30 mm;
width: 3 mm) were pre-treated in the following ways: (i) raw potato slices ‘‘control’’; (ii) control slices
were blanched in hot water at 85 C for 3.5 min; (iii) blanched slices were dried in hot air until reaching
a moisture content of w0.6 g water/g dry basis. The slices were fried under vacuum (5.37 kPa, absolute
pressure, at 120, 130 and 140 C) and atmospheric conditions (at 180 C). Two models based on the Fick’s
law were used to describe water loss: (i) with a constant effective diffusive coefficient; and (ii) with
a variable effective diffusive coefficient. Oil uptake data were fitted to an empirical model, with a linear
behavior for short times whereas the model was time independent for long times. The variable diffusivity
model better fitted experimental water loss, giving values of effective diffusivity between 4.73 109
and 1.80 108 m2
/s. The proposed model for the study of the kinetics of oil uptake fitted the experimental
data properly. Control and blanched vacuum fried potato chips increased their final oil contents
to 57.1% and 75.4% respectively, when compared with those fried at atmospheric pressure. However, the
oil absorption of dried vacuum fried potato chips diminished by w30%.
2