Shrinkage of cellular food during air drying

For all drying conditions used in this study, shrinkage of carrot samples (cylinders and slabs) had a linear relationship with moisture content during drying. For potato, however, a change in the slope of the shrinkage curve as a function of moisture content during drying was observed for cylinder samples. For potato slabs, only those having initial moisture contents lower than 5.5 ± 0.5 kg water/kg dm showed a similar change in slope, otherwise slabs presented a straight line for the whole water content range. The air temperature and air speed had no effect on the shrinkage behaviour of both carrot and potato samples under the operation conditions used in this study. No significant impact of glass transition on shrinkage of carrot and potato samples has been found, and if any this impact would be considered minor. Differences in starch content, in structure of the cellular material and its relationship with mechanical properties of material may explain the different shrinkage behaviour observed in this work.