title: Effect of molecular weight reduction by gamma irradiation on chitosan film properties.
abstract: The present work aimed the influence of molecular weight (MW) reduction by irradiation with (60)Co and polymer concentration on some physical properties of chitosan films. Irradiation of chitosan with a MW of 275.221 kDa and 74.74% of deacetylation degree was performed using a (60)Co source to provide doses of 5, 10, 20 and 50 kGy to obtain chitosans with molecular weights of 247.847, 221.563, 126.469 and 77.063 kDa, respectively. Films were prepared via the solution casting method. Film-forming solutions (FFS) of chitosan irradiated or not, were prepared at 1.5 and 2% (w/v) in a solution of lactic acid at 1% (v/v) and 0.1% (v/v) of Tween 80. The FFS were poured into glass plates of 400 cm(2) and dried at 60 °C during 10h without airflow. The decrease of MW and increase of chitosan concentration increased the tensil strength and water vapor permeability while decreased the elongation at break of the films. The chitosan MW did not significantly influence (p>0.05) the water solubility of films within a same polymer concentration. There was a decrease in the films' brightness with the increase of concentration and a decrease of the MW of irradiated chitosan, while the b* values of films increased and there was an increasing tendency of their apparent opacity.
authors.affiliation: Pharmacy and Food Institute, University of Havana, St. 222 No. 2317, ZC 13600 Havana, Cuba. Electronic address: marioifal@gmail.com.
authors.forename: Mario A
authors.initials: MA
authors.lastname: García
authors.affiliation: Pharmacy and Food Institute, University of Havana, St. 222 No. 2317, ZC 13600 Havana, Cuba.
authors.forename: Liliam
authors.initials: L
authors.lastname: Pérez
authors.affiliation: Drugs Research and Development Center, Ave. 26 No. 1605, Havana, Cuba.
authors.forename: Nilia
authors.initials: N
authors.lastname: de la Paz
authors.affiliation: Food Industry Research Institute, Carretera al Guatao km 3 ½, Havana, CP 19200, Cuba.
authors.forename: Juan
authors.initials: J
authors.lastname: González
authors.affiliation: Radiobiology Department, Center for Technological Applications and Nuclear Development, St. 30 No. 502, Playa, Havana, Cuba.
authors.forename: Manuel
authors.initials: M
authors.lastname: Rapado
authors.affiliation: Pharmacy and Food Institute, University of Havana, St. 222 No. 2317, ZC 13600 Havana, Cuba.
authors.forename: Alicia
authors.initials: A
authors.lastname: Casariego
mesh_terms: D048271:Chitosan / Q000737:chemistry* / Q000528:radiation effects; D018857:Food Packaging / Q000295:instrumentation; D005720:Gamma Rays; D019344:Lactic Acid / Q000737:chemistry; D008970:Molecular Weight; D010539:Permeability; D011136:Polysorbates / Q000737:chemistry; D012995:Solubility; D013227:Steam; D013718:Tensile Strength
chemical_list: D011136:Polysorbates; D013227:Steam; D019344:Lactic Acid; D048271:Chitosan
keywords: Chitosan; Films; Gamma irradiation; Mechanical properties; Water vapor permeability