title: Effect of polysaccharide structure on mechanical and thermal properties of galactomannan-based films.
abstract: Films were prepared from guar gum and locust bean gum galactomannans. In addition, enzymatic modification was applied to guar gum to obtain structurally different galactomannans. Cohesive and flexible films were formed from galactomannans plasticized with 20-60% (w/w of polymer) glycerol or sorbitol. Galactomannans with lower galactose content (locust bean gum, modified guar gum) produced films with higher elongation at break and tensile strength. The mechanical properties of films were improved statistically significantly by decreasing the degree of polymerization of guar gum with mannanase treatments (4 h) of 2 and 10 nkat/g, whereas 50 nkat/g produced films with low elongation at break and tensile strength. Galactomannans with approximately 6 galactose units per 10 mannose backbone units resulted in films with 2 peaks in loss modulus spectra, whereas films from galactomannans with approximately 2 galactose groups per 10 mannose units behaved as a single phase in dynamic mechanical analysis.
authors: Department of Applied Chemistry and Microbiology, University of Helsinki, FI-00014, Helsinki, Finland. kirsi.s.mikkonen@helsinki.fi
authors: Kirsi S
authors: KS
authors: Mikkonen
authors: Hannu
authors: H
authors: Rita
authors: Harry
authors: H
authors: Helén
authors: Riku A
authors: RA
authors: Talja
authors: Lea
authors: L
authors: Hyvönen
authors: Maija
authors: M
authors: Tenkanen
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002621:Chemistry / Q000379:methods*; D005685:Galactans / Q000737:chemistry*; D005690:Galactose / Q000737:chemistry / Q000031:analogs & derivatives; D005696:Galactosidases / Q000378:metabolism; D005990:Glycerol / Q000737:chemistry; D008351:Mannans / Q000737:chemistry*; D008422:Materials Testing; D015233:Models, Statistical; D053149:Plant Gums / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D013012:Sorbitol / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014242:Trichoderma / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D011134:Polysaccharides; D014867:Water; C012990:galactomannan; D013012:Sorbitol; C007894:guar gum; D005696:Galactosidases; D005990:Glycerol; D005690:Galactose