Abstract
We conducted atmospheric freeze drying (AFD) of fresh-cut Japanese radish (daikon) at different temperatures (0, －5, －10, －18 °C) with an air speed of 0.43 m・s－1, and evaluated moisture content changes. We assessed samples dried by AFD for surface color, soluble solids content ( °Brix), rehydration ratio, and texture (breaking stress and initial elasticity) after rehydration. In the rehydration and texture tests, we compared AFD using －5 °Csamples and samples dried by hot air at 60 °C. An exponential model was used to describe the sample moisture content during AFD, which decreased exponentially with drying constant with an Arrhenius-type temperature dependency. Compared to the sample dried at 60 °C, the rehydration ratio was 1.29 times higher for AFD at －5 °C, and the sample showed a large number of voids. There were no significant differences between the －5 °Cand 60 °Csamples in terms of breaking stress or initial elasticity. These results indicate that AFD is an effective drying method for preserving the quality of products.
