title: Characterization of physicochemical properties of carboxymethyl agar.
abstract: A series of carboxymethyl agars (CMAs) with different degree of substitution (DS) were prepared, and their properties were determined and analyzed. The results showed that with the increase of DS, the dissolving temperature, the gelling temperature, the gel melting temperature, the gel strength, the gel hardness, the gel fracturability, and the solution apparent viscosity of CMA all decreased, except that its gel cohesiveness and gel springiness increased. The variation process of agar molecules in solution from coil to helix could be observed by measuring the optical rotation of the solution at such a low concentration, at which even the solution could not form a gel. The gel skeleton microstructures of both agar and CMA were of porous network structure, and the pore size of CMA became smaller and denser with the increase of its DS. After carboxymethylation, the agar hygroscopicity was improved, but its thermal stability was lowered.
authors.affiliation: College of Chemical Science and Engineering, Qingdao University, Qingdao 266071, China.
authors.forename: Mingzhao
authors.initials: M
authors.lastname: Cao
authors.affiliation: College of Chemical Science and Engineering, Qingdao University, Qingdao 266071, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Chemical Science and Engineering, Qingdao University, Qingdao 266071, China.
authors.forename: Jimei
authors.initials: J
authors.lastname: Luan
authors.affiliation: College of Chemical Science and Engineering, Qingdao University, Qingdao 266071, China. Electronic address: zhangxdqd@hotmail.com.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000362:Agar / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D008745:Methylation; D044366:Transition Temperature; D014783:Viscosity
chemical_list: D002264:Carboxylic Acids; D005782:Gels; D000362:Agar
keywords: Agar; Carboxymethylation; Gelling temperature; Optical rotation; Thermal stability