title: Effects of micro electric current load during cooling of plant tissues on intracellular ice crystal formation behavior and pH.
abstract: Cryopreservation techniques are expected to evolve further to preserve biomaterials and foods in a fresh state for extended periods of time. Long-term cryopreservation of living materials such as food and biological tissue is generally achieved by freezing; thus, intracellular freezing occurs. Intracellular freezing injures the cells and leads to cell death. Therefore, a dream cryopreservation technique would preserve the living materials without internal ice crystal formation at a temperature low enough to prevent bacterial activity. This study was performed to investigate the effect of micro electrical current loading during cooling as a new cryopreservation technique. The behavior of intracellular ice crystal formation in plant tissues with or without an electric current load was evaluated using the degree of supercooling, degree of cell deformation, and grain size and growing rate of intracellular ice crystal. Moreover, the transition of intracellular pH during plant tissue cooling with or without electric current loading was also examined using the fluorescence intensity ratio to comprehend cell activity at lower temperatures. The results indicated that micro electric current load did not only decrease the degree of cell deformation and grain size of intracellular ice crystal but also reduced the decline in intracellular pH due to temperature lowering, compared with tissues subjected to the same cooling rate without an electric current load. Thus, the effect of electric current load on cryopreservation and the potential of a new cryopreservation technique using electric current load were discussed based on these results.
authors.affiliation: Graduate School of Mechanical Engineering, Kanagawa Institute of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa 243-0292, Japan. Electronic address: s1291001@cco.kanagawa-it.ac.jp.
authors.forename: Takako
authors.initials: T
authors.lastname: Ninagawa
authors.affiliation: Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Ueda 3-18-8, Morioka, Iwate 020-8550, Japan. Electronic address: ykawa@iwate-u.ac.jp.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kawamura
authors.affiliation: Department of Mechanical Engineering, Oita National College of Technology, 1666 Maki, Oita, 870-0152, Japan. Electronic address: konishi@oita-ct.ac.jp.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Konishi
authors.affiliation: Graduate School of Mechanical Engineering, Kanagawa Institute of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa 243-0292, Japan. Electronic address: narumi@me.kanagawa-it.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Narumi
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D004560:Electricity; D005615:Freezing; D006863:Hydrogen-Ion Concentration; D007053:Ice; D059828:Plant Cells
chemical_list: D007053:Ice
keywords: Electric current load; Ice crystal; Intracellular freezing; Intracellular pH; Plant; Supercooling