Pre-treatment with Ethanol to enhance potato drying and rehydration

Although drying is widely used to prolong food stability, this is a long process, which needs enhancement. This work evaluated ethanol as a pre-treatment to improve the convective drying and further rehydration of potato slices. Pre-treatments included control (CT, without any pre-treatment) and samples immersed in ethanol for 15 minutes (E15) and 30 minutes (E30). The potato slices were convectively dried using hot-air at 40 ºC and 1 m.s-1 until constant weight, being then rehydrated by immersion in distilled water at 25 ºC. Effects on drying and rehydration kinetics were studied using the Page and Peleg Models. Significant differences during drying were observed for the k parameter of Page Model, whose value was two times higher in the pre-treatment E30 in relation to the others. The parameter n did not exhibit significant difference among the treatments, with all of them showing a super-diffusive behavior (n>1) - which was attributed to capillarity. The CT sample presented a rate of rehydration ~33% lower than E30 and ~26% lower than E15 pre-treatments. In contrast, there was no significant difference in equilibrium moisture among treatments. In conclusion, the ethanol improved both drying and rehydration processes of potato slices.