Influence of Thickness on Ice Crystal Formation in Strawberry during Freeze-drying

This study demonstrates the capability of X-ray Micro-computed Tomography (XMT) technique to characterize the internal ice crystal microstructure of fresh strawberry after freezing. The method requires freeze-drying of the sample to remove frozen water before scanning to indicate ice crystal and internal structure of the material. Results are presented for the 2-D ice crystals formed within strawberry frozen at different rates. The dendrite spacing of ice crystals has been related to the freezing conditions of the material. Moreover ice crystal parameters such as size, volume and width can be measured by using the technique. The overall results indicate that the ice crystal distribution within strawberries diverse with the axial distance of the material from its cooling surface and thickness of the samples. In the latter stage the ice crystal size is bigger when the material is far from the cooling surface while the smallest ice crystal size will be formed from the thickness of the materials.