title: Preparation of starch-poly-glutamic acid graft copolymers by microwave irradiation and the characterization of their properties.
abstract: Graft copolymers of waxy maize starch and poly-γ-glutamic acid (PGA) were produced in an aqueous solution using microwave irradiation. The microwave reaction conditions were optimized with regard to temperature and pH. The temperature of 180°C and pH7.0 were the best reaction conditions resulting in a PGA graft of 0.45% based on nitrogen analysis. The average graft content and graft efficiency for the starch-PGA graft copolymer prepared at 180°C and pH7.0 were 4.20% and 2.73%, respectively. The starch-PGA graft copolymer produced at 180°C and pH7.0 could absorb more than 20 times its own weight amount of water and form a gel. The preliminary rheology study revealed that the starch-PGA graft copolymer gel exhibited viscoelastic solid behavior while the control sample of waxy starch showed viscoelastic liquid behavior.
authors.affiliation: National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, 1815 North University Street, Peoria, IL 61604, USA. Electronic address: james.xu@ars.usda.gov.
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Xu
authors.affiliation: National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, 1815 North University Street, Peoria, IL 61604, USA.
authors.forename: Elizabeth F
authors.initials: EF
authors.lastname: Krietemeyer
authors.affiliation: National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, 1815 North University Street, Peoria, IL 61604, USA.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Finkenstadt
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Solaiman
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Ashby
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Garcia
mesh_terms: D065966:Absorption, Physicochemical; D008872:Microwaves; D009584:Nitrogen / Q000737:chemistry; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D012212:Rheology; D012995:Solubility; D013213:Starch / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: C511775:poly(gamma-glutamic acid); D014867:Water; D011099:Polyglutamic Acid; D013213:Starch; D009584:Nitrogen
keywords: Graft copolymers; Poly-glutamic acid (PGA); Starch