Freezing Injury and Rheological Properties of Agricultural Products

Abstract

Time changes in electrical and rheological properties of carrot and potato cell tissues after freezing-thawing or chloroform-vapor treatment were compared to clarify the mechanism of cell tissue softening by freezing injury. Integrity of cell plasma membrane was analyzed by the electrical measurement and rheological properties of cell tissues were determined by the vibrating reed method. Changes in the rheological properties by the chloroform-vapor treatment were assumed to be caused only by the loss of turgor pressure, while those by the freezing-thawing were caused by loss of this pressure and injuries to the cell wall and intercellular structure. The change in the rheological properties of carrot and potato tissue by the freezing-thawing and chloroform-vapor treatment were compared to determine the contribution ratio of the loss of turgor pressure and injuries to the cell wall and intercellular structure, which are known as major causes of softening by freezing injury. Findings showed that the loss of turgor pressure due to plasma membrane injury is the main reason for cell tissue softening by freezing injury while injuries to the cell wall and intercellular structure have an auxiliary role.

PFG-NMR Study for Evaluating Freezing Damage to Onion Tissue

“…22) However, our light microscopy findings revealed minimal changes in onion tissues after exposure to chloroform (Fig. 5).…”

Effect of Freezing on Electrical and Rheological Properties of Food Materials

“…This means that the structure change reflecting the large change in electrical properties for these plant tissues is responsible for the change in the rheological properties. In the plant cell tissue, the loss of turgor pressure by injury of the plasma membrane is considered to be the major cause of softening after freezing-thawing (Ohnishi et al, 2003).…”

“…In plant tissue, this effect brings a large change in rheological properties causing softening (Ohnishi et al, 2003), which is one of the most important types of deterioration in frozen storage. In contrast, the rheological properties of meat tissue hardly change before and after freezing-thawing although it has a cellular structure as well as does plant tissue.…”

Estimation of Damage to Cells of Japanese Radish Induced by High Pressure with Drying Rate as Index

“…Measurement of dielectric properties for fresh agroproduct, indicated characteristic Cole-Cole arcs showing the presence of the cell structure. 11,12,19) The physicochemical (chloroform-vapor, heat, freeze-thaw, and high-pressure over 400 MPa) treated samples did not similarly show Cole-Cole arcs, indicating the disappearance of cell structure. Dielectric measurement was a fast, less-invasive method, but was not as sensitive.…”

“…Fax: +81-22-717-8946; E-mail: shigeakiu@bios.tohoku.ac.jp nique. 19) Dielectric measurement was not sufficient to investigate the differences, in cell damage caused by different treatments.…”