title: Influence of reaction parameters on carboxymethylation of rice starches with varying amylose contents.
abstract: The influence of reaction parameters on the carboxymethylation of rice starches with different amylose contents was investigated. Rice starches with varying amylose contents showed various degrees of susceptibility to the reaction conditions. The maximum degree of substitution (DS) for all three rice starches was obtained under similar reaction conditions which involved a reaction medium consisting of isopropanol-water at the ratio of 90:10, a molar ratio of NaOH:AGU at 1.5 and a reaction temperature and time of 40°C and 3 h. Under these conditions, the DS for all rice starches was similar; however, when the reaction was performed under conditions using lower NaOH concentration, the effect of starch types on the DS was observed. The results could be explained in terms of the granular/structural features of the different rice starches, their degrees of granular swelling as influenced by the reaction conditions and the accessibility of the etherifying reagents to starch molecules.
authors.affiliation: Cassava and Starch Technology Research Unit, National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Pathum Thani, Thailand.
authors.forename: Kunruedee
authors.initials: K
authors.lastname: Sangseethong
authors.affiliation: Kasetsart Agricultural and Agro-Industrial Product Improvement Institute, Kasetsart University, Bangkok, Thailand.
authors.forename: Pathama
authors.initials: P
authors.lastname: Chatakanonda
authors.affiliation: Cassava and Starch Technology Research Unit, National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Pathum Thani, Thailand.
authors.forename: Rungtiva
authors.initials: R
authors.lastname: Wansuksri
authors.affiliation: Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Bangkok, Thailand. Electronic address: aapkrs@ku.ac.th.
authors.forename: Klanarong
authors.initials: K
authors.lastname: Sriroth
mesh_terms: D000688:Amylose / Q000737:chemistry*; D007700:Kinetics; D008745:Methylation; D012275:Oryza / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013213:Starch / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D012997:Solvents; D014867:Water; D012972:Sodium Hydroxide; D013213:Starch; D000688:Amylose
keywords: Amylose content; Carboxymethylation; Reaction conditions; Rice starch