Abstract
Osmotic dehydration was examined as a preventive method of tissue softening of agricultural products by the freezing injury. Carrot and potato tissues were dehydrated in 50% (w/w) sucrose solution at 10℃ for 24 hours. Injury of cell plasma membrane by freezing-thawing or osmotic dehydration was analyzed by the electrical measurement. Rheological properties of cell tissues were determined by the vibrating reed method. Cell plasma membrane of carrot tissue was relatively resistant to osmotic dehydration. Therefore, viscoelasticity of rehydrated carrot tissue pretreated by the osmotic dehydration before freezing-thawing showed 2-3 times higher that of control without osmotic dehydration, suggesting the effect the osmotic dehydration to prevent tissue softening after freezing-thawing. On the contrary, cell plasma membrane of potato tissue received a serious damage by the osmotic dehydration so that pretreatment by the osmotic dehydration was not effective for the prevention of freezing injury in this case. This result suggested some difference in the cell membrane structure between potato and carrot.
