The Effects Of Konjac Glucomannan And Micromolecule On Crystal Structure Of Gellan Family Gum

Crystalline is the most original and stable phase,which is the start of gaining comprehensive understanding of conformation and characters.Nowadays,people pay more and more concernson the research of polysaccharide crystalline state,but the complexity and particularity of the structure of polysaccharides has become the bottleneck in the field.Study on the factors affecting the crystalline phase of polysaccharides could be vital important.Based on the researches of KGM helical conformation and the liquid crystalline state,and the synchrotron radiation X-ray fiber diffraction methods of the cooperation team of Purdue University,the effects of KGM and micromolecule on the crystalline state of gellan family polysaccharides were studied.This paper attempted to use synchrotron radiation X-ray fiber diffraction techniques to study the effects of diffeerent factors on characteristics and type lattice of gellan family polysaccharide crystalline,analyzed the internal molecular conformation,rheology and melt stability.The main results are as follows:(1)KGM had different effects on gellan family polysaccharides.As for optimal diutan gum(DG)and wellan gum(WG),KGM molecular chain could conduct different kinds of interactions with gellan gum molecule chain.KGM had a synergistic effect with DG and WG which contributed a more compact and well-aligned arrangement of molecules,what's more,the molecular helical structure had been changed,which could promote the formation of orthorhombic crystal structure,and the diffraction layer lines became more clear,improving the sol rheology.However KGM had no synergies with HAG and LAG,and damaged their crystalline state,which caused the reduction of sol rheology.There was little difference between heating and microwaving treatment.(2)The effects of metal ions on optimal DG and WG could becontrolledby valence metal ions.The synchrotron radiation X-ray diffraction results showed that the trigonal crystal structure(Lattice parameter is a=b?c)of optimal DG was constituted by three times single screw under the action of a monovalent metal ions,whose main intermolecular interaction was-COO---M+--W--M+---OOC-and-COO---M+--W-M+---OC-,but the trigonal crystal structure of optimal DG and WG was constituted by three times double screw under the action of divalent metal ion,whose main intermolecular interaction was-COO---M2+---OOC-and-COO---M2+---OC-.The rheological results indicated that the cross-linking of a monovalent metal ion didn't significantly improve the rheology character of optimal DG and WQ while the cross-linking of the divalent metal ion enhanced the interaction between optimal DG and WG,and the rheology of the system had been significantly improved,the melt stability was enhanced.(3)The non-covalent forces in maintaining crystalline stablility of optimal DG and WG was mainly metal bonding force,hydrogen bonding force and others are the secondary forces.The addition of urea,to some extent,undermined the crystalline structure of DCa and WCa,interrupted spiral intermolecular hydrogen bonds,showed the class of crystalline,and different concentrations of urea had almost no effect on rheology of optimal DG,while low concentrations of urea enhanced the rheological characteristic of WG through the complications.Guanidine hydrochloride did not destroy the crystalline structure of DCa and WCa completely,but the trigonal dislocated to orthorhombic.This result verified ionic bond was the major non-covalent force in maintaining DCa and WCa.Rheological results showed guanidine hydrochloride could significantly improve the performance of DCa and WCa gel at low temperatures,which may be related to the nature of the electrolyte guanidine hydrochloride.(4)The calcium ions and KGM had exclusive coexistence impact on gellan gum sugar class crystalline.Addition of Ca2+ could make KD and KW to transform from amorphous amorphous to crystalline trigonal system,enhancing rheology and melt ability.But KGM could reduce the lattice size of DCa and WCa and weaken rheology.KGM and divalent metal ions could promote the formation and growth of crystals of optimal DG and WG,and improve their melting and rheological stability.However,when they both were present,KGM could block the interaction between the divalent metal ions with optimal DG and WG.