title: Kinetic analysis for the isomerization of cellobiose to cellobiulose in subcritical aqueous ethanol.
abstract: The isomerization of cellobiose to cellobiulose, and other degradation reactions of cellobiose were investigated in subcritical aqueous ethanol with concentrations of ethanol ranging from 0 to 60% (w/w) and at temperatures ranging from 170 to 200 °C. The maximum yield of cellobiulose (ca. 40%) was obtained from the treatment of cellobiose in 60% (w/w) aqueous ethanol at 190 °C. Glucose and fructose were also detected as byproducts. The concentration-time integral method was employed to analyze the rate constants for the isomerization and degradation processes. The rate constant of cellobiose isomerization to cellobiulose was greater than those of the degradation reactions under all experimental conditions, and it increased significantly with treatment temperature and ethanol concentration. However, the use of higher temperatures and ethanol concentrations was restricted due to decomposition of the saccharides and the low solubility of cellobiose, respectively. The effect of initial feed concentration (0.5-5.5% w/w) was also studied. The maximum productivity of cellobiulose, 54.1 kg/(h m(3)-reactor), was accomplished at a feed concentration of 5.5% (w/w) in 20% (w/w) subcritical aqueous ethanol.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Nontanut
authors.initials: N
authors.lastname: Soisangwan
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Gao
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Department of Food Technology, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom 73000, Thailand.
authors.forename: Pramote
authors.initials: P
authors.lastname: Khuwijitjaru
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. Electronic address: adachi@kais.kyoto-u.ac.jp.
authors.forename: Shuji
authors.initials: S
authors.lastname: Adachi
mesh_terms: D002475:Cellobiose / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D005632:Fructose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D007536:Isomerism; D007700:Kinetics; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D002475:Cellobiose; D005632:Fructose; D000431:Ethanol; D005947:Glucose
keywords: Cellobiulose; Isomerization; Kinetics; Subcritical aqueous ethanol