title: The effect of solvent composition on grafting gallic acid onto chitosan via carbodiimide.
abstract: The primary antioxidant (AOX) activity of chitosan can be introduced by grafting of phenolic compound - gallic acid (GA) to its amino and/or hydroxyl groups. The objective of this study was to investigate the effect of ethanol (EtOH) concentration (0%, 25%, 50%, and 75% in water) on efficiency of grafting GA onto chitosan in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinimide (NHS). The grafting was confirmed by FTIR and the efficiency was quantified as Folin's total phenolics. When pure deionized water was used as a sole solvent (0% EtOH), GA was grafted to chitosan at the largest extent (285.9mg GA/g chitosan). As the concentration of EtOH increased, the grafting efficiency proportionally decreased. NMR studies showed that EtOH inhibited grafting of GA by prohibiting the production of the intermediate - NHS ester. The results confirm that the concentration of EtOH in grafting solution significantly affects grafting efficiency of GA on chitosan.
authors.affiliation: Department of Food Science and Technology, University of Tennessee, 2510 River Drive, Knoxville, TN 37996, United States.
authors.forename: Ping
authors.initials: P
authors.lastname: Guo
authors.affiliation: Center for Renewable Carbon, University of Tennessee, 2506 Jacob Drive, Knoxville, TN 37996, United States.
authors.forename: John D
authors.initials: JD
authors.lastname: Anderson
authors.affiliation: Center for Renewable Carbon, University of Tennessee, 2506 Jacob Drive, Knoxville, TN 37996, United States.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Bozell
authors.affiliation: Department of Food Science and Technology, University of Tennessee, 2510 River Drive, Knoxville, TN 37996, United States. Electronic address: LanaZ@utk.edu.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Zivanovic
mesh_terms: D002234:Carbodiimides / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D005707:Gallic Acid / Q000737:chemistry*; D010084:Oxidation-Reduction; D012995:Solubility; D012997:Solvents / Q000737:chemistry*; D013388:Succinimides / Q000737:chemistry
chemical_list: D002234:Carbodiimides; D012997:Solvents; D013388:Succinimides; C074139:1-ethyl-3-(3-dimethylaminoethyl)carbodiimide; D000431:Ethanol; D005707:Gallic Acid; D048271:Chitosan; C001426:N-hydroxysuccinimide
keywords: Antioxidant packaging; Chitosan; Gallic acid; Grafting