A new bacterial exopolysaccharide (YAS34). II. Influence of thermal treatments on the conformation and structure. Relation with gelation ability.
This paper describes an original mechanism of evolution of a polysaccharide system occurring during thermal treatments. Under its native conformation, the YAS34 polymer presents a solution character in the dilute and semi-dilute regimes. However, the zero shear rate viscosity indicates existence of interchain interactions which disappear on the deacetylated polymer. Thermal treatments over the temperature of conformational change produce a progressive and irreversible evolution of the physical properties when the polymer is under its sodium salt form. This evolution was related to a modification of the arrangement of acetyl substituents. The heated polysaccharide gives thermoreversible gel which is very elastic. A gelation mechanism is proposed based on formation of helical segments connecting the network.
Villain-Simonnet
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Centre de Recherches sur les Macromolécules Végétales, CNRS, B.P. 53, affiliated with Joseph Fourier University, 38041, Grenoble, France.
Milas
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Rinaudo
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D000107:Acetylation; D002236:Carbohydrate Conformation; D005780:Gelatin / Q000737:chemistry; D006361:Heating; D007700:Kinetics; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012996:Solutions
D011135:Polysaccharides, Bacterial; D012996:Solutions; D005780:Gelatin