Abstract
Carrot, broccoli and potato tissue were osmotically dehydrated by immersion in 50%(w/w) sucrose solution and their rheological properties were measured before and after freezing-thawing-rehydration. Although the dynamic elasticity and viscosity became smaller after freezing-thawing as compared to the fresh sample, the dehydrated samples, except potato, showed much higher retention of rheological properties than the untreated sample. In measurement of impedance, the radius of the Cole-Cole arc, an index of the intactness of cell plasma membrane, showed good correlations with the rheological properties for carrot and broccoli. The osmotically dehydrated sample showed much less drip than the untreated sample after freezing-thawing-rehydration. These results indicate that osmotic dehydrofreezing protects the cell structure, in particular the cell plasma membrane, against freezing injury to give reduced softening after freezing-thawing.
