title: Visualisation of xanthan conformation by atomic force microscopy.
abstract: Direct visual evidence obtained by atomic force microscopy demonstrates that when xanthan is adsorbed from aqueous solution onto the heterogeneously charged substrate mica, its helical conformation is distorted. Following adsorption it requires annealing for several hours to restore its ordered helical state. Once the helix state reforms, the AFM images obtained showed clear resolution of the periodicity with a value of 4.7nm consistent with the previously predicted models. In addition, the images also reveal evidence that the helix is formed by a double strand, a clarification of an ambiguity of the xanthan ultrastructure that has been outstanding for many years.
authors.affiliation: Asylum Research an Oxford Instruments Company, Halifax Rd., High Wycombe, Buckinghamshire, HP12 3SE, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Moffat
authors.affiliation: Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK.
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Morris
authors.affiliation: Hydrocolloids Research Centre, Institute of Food Science & Innovation, Faculty of Science & Engineering, University of Chester, Parkgate Road, Chester CH1 4BJ, UK.
authors.forename: Saphwan
authors.initials: S
authors.lastname: Al-Assaf
authors.affiliation: Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK. Electronic address: patrick.gunning@ifr.ac.uk.
authors.forename: A Patrick
authors.initials: AP
authors.lastname: Gunning
keywords: Atomic force microscopy; Counterions; Structural conformation; Xanthan