Effect of starch retrogradation on texture of potato chips produced by low-pressure superheated steam drying

The effects of the degree of starch retrogradation, initial slice thickness and final moisture content on the texture of potato chips dried by low-pressure superheated steam drying (LPSSD) were investigated in this study. Potato slices of different initial thicknesses (1.5, 2.5 and 3.5 mm) were pretreated with three different methods (blanching and then freezing for 24 h, blanching and then repeated freezing/thawing either for 3 or 5 cycles) to study the effects of these pretreatment methods on the degree of starch retrogradation. The potato slices were then dried by LPSSD at 90 °C and absolute pressure of 7 kPa to three levels of final moisture content (1.5%, 2.5% and 3.5% (d.b.)) to investigate the drying kinetics and the quality of dried potato chips in terms of hardness, toughness and crispness as well as degree of crystallinity by X-ray diffraction technique. The various pretreatment methods were found to have an obvious effect on the rates of moisture reduction of the samples. Higher degrees of starch retrogradation led to an increase in the hardness and toughness of dried chips, but did not show any significant effect on the crispness of the chips. An increase in the degree of starch retrogradation led to higher degree of crystallinity of dried potato chips.