Study on the mechanism of volume expansion and texture formation of apple cube dried by instant controlled pressure drop drying (DIC)

Abstract

Abstract In order to control the quality of the DIC dried food products, this study investigated the energy conversion and the expansion force generation mechanism at the instantaneous pressure drop during the DIC treatment. Their effects on the product texture formation were analyzed. The results showed that the instantaneous vaporization of water at the moment of decompression could generated the expansion energy, which caused the expansion of the internal pores of the apple cube. Hence the volume and absolute porosity of the apple cube were increased. In addition, the pore walls of apple cube with the transition moisture content of 1.068 g/g (d.b.) were collapsed after DIC. Furthermore, DIC apple cube products had the optimal volume expansion ratio (2.317 ± 0.310), hardness (139.44 ± 16.52 N) and crispness (90 ± 17) at the transition moisture content of 0.152 ± 0.018 g/g (d.b.).