title: Effects of acidic functional groups on dielectric properties of sodium alginates and carrageenans in water.
abstract: This study investigated the dielectric properties of sodium alginates and carrageenans in water at frequencies between 100 MHz and 20 GHz in regard to water-hydrocolloid interactions via acidic functional groups. Both sodium alginates and carrageenans showed conduction loss at lower frequencies and dielectric loss at higher frequencies. Reduction and desulfation of sodium alginates and carrageenans, which decreased the numbers of acidic functional groups, decreased their conduction loss. In addition, H(+)-form carrageenans showed the highest ionic conduction. Correlational analysis of dielectric properties and related physical parameters showed that the loss tangent (tanδ) of the hydrocolloid solution was determined by the conductivity of the aqueous solution. Especially at pH below 2, strong H(+) conduction was associated with high tanδ probably due to the Grotthuss mechanism. The molecular dynamics of free water and H(+), viscosity conditions were also suggested to be associated with dielectric property of water-hydrocolloid system.
authors.affiliation: Oceanography Section, Science Research Center, Kochi University, Akebono-cho 2-5-1, Kochi 780-8520, Japan. Electronic address: stsubaki@kochi-u.ac.jp.
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Tsubaki
authors.affiliation: Oceanography Section, Science Research Center, Kochi University, Akebono-cho 2-5-1, Kochi 780-8520, Japan; Usa Marine Biological Institute, Kochi University, Inoshiri, Usa, Tosa, Kochi 781-1164, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Hiraoka
authors.affiliation: Department of Applied Science, Faculty of Science, Kochi University, Akebono-cho 2-5-1, Kochi 780-8520, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Hadano
authors.affiliation: Center for Advanced Marine Core Research, Kochi University, B200 Monobe, Nankoku, Kochi 783-8502, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Okamura
authors.affiliation: Department of Applied Science, Faculty of Science, Kochi University, Akebono-cho 2-5-1, Kochi 780-8520, Japan.
authors.forename: Tadaharu
authors.initials: T
authors.lastname: Ueda
authors.affiliation: Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji 611-0011, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishimura
authors.affiliation: Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji 611-0011, Japan.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Kashimura
authors.affiliation: Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji 611-0011, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Mitani
mesh_terms: D000143:Acids / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry*; D002351:Carrageenan / Q000737:chemistry*; D017097:Electric Impedance; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D000143:Acids; D000464:Alginates; D006603:Hexuronic Acids; D014867:Water; D020723:Glucuronic Acid; D002351:Carrageenan
keywords: Carrageenan; Dielectric measurement; Microwave heating; Sodium alginate