Effect Of Ion System On Rheological Properties And Structures Of Konjac Glucomannan

Konjac glucomannan is an important plant source of bioactivity polysaccharides.It is very important for konjac glucomannan's further processing to study its properties,enhance its potential value and extend the scope of applications.In this article,konjac glucomannan's rheological properties and micro-conformation changes in different ionic system wered analyzed by means of rheometer,texture analyzers,and other objects detection and spectroscopic means,focusing on the properties of variation and micro-conformation changes of interactions of the iron ions,potassium ions and copper ion with konjac glucomannan;and initially exploring the mechanism of ions interaction resorting to its microscopic structure and system.The findings were obtained as follows.(1)Firstly,the static rheological and dynamic rheological properties of konjac glucomannan in different ion solutions were studied by the numbers,and the results are as follows.When konjac glucomannan hydrosol was in lower concentration,it showed the nature of the Newtonian fluid;when the concentration was larger than 1%,its performance was of non-Newtonian fluid,showing a pseudoplastic viscosity which was decreased with increasing of temperature.Potassium ion,copper ion and other metal ions would result in the increasing of sol solution viscosity.The higher the ion valence was,the greater was impact of viscosity.Under the conditions of this study,konjac glucomannan sol solution was diluted at the presence of iron ion.The konjac glucomannan viscosity and stress were changed significantly on the influence of anions of chloridion,sulfate ion,root carbonate ion.Among of the anions,sulfate ion played an important part in the increases of system viscosity.and improved the gel properties of konjac glucomannan.Chloridion in the system had a similar impact,but the impact was weaker.Konjac glucomannan viscosity decreased as the shear rate increased for the effect of root carbonate ion.With the influence of anion,konjac glucomannan showed the characteristics of shear thinned and changed for shear rate of 0.19s-1.Konjac glucomannan's initial viscosity increased significantly by adding of sucrose,guanidine hydrochloride,glycerol,ethanol and other substances.The modulus of the konjac glucomannan system was affected by the adding of different ions,and the gel temperature point was obviously anticipated,promoting the konjac glucomannan gel.(2)Konjac glucomannan's solution properties and micro-conformation were impacted greatly in iron ion system.The viscosity changed.With the increase of concentrations,the viscosity increased more significantly in the same effect of shear stress and when system was joined in 0.1 mol/L 6mL FeCl3,there was a sharp rise in viscosity whose reduction was larger than this value,and this was the optimal concentration of the reaction.Different pH values had a significant impact on the system.Under acidic conditions,konjac glucomannan sol was in the solution state,however,under alkaline conditions it was still a thick jelly.Then,dynamic rheological properties were studied.It showed that G' and G" appeared intersection in advance compared with single konjac glucomannan gel point with 64? and the low frequencies.It could conclude that coordination role of iron ion and konjac glucomannan occurred,showing a lower modulus and viscosity.Infrared scanning analysis showed with the acidic conditions,the original konjac glucomannan system characteristic absorption peaks had disappeared.It was seen from the graph,iron ion and konjac glucomannan were with the strong interaction between systems,causing changes of the molecular chain structure of konjac glucomannan.UV scanning analysis showed absorption peak of Fe3+-KGM co-ordination system was in 240?250nm,to generate a new complex.And CD analysis showed that the molecular chain structure of konjac glucomannan has some changes.(3)The law and mechanism of potassium ion affecting the characteristics of konjac glucomannan solution and gel properties were discussed with the conclusions and results as follows:konjac glucomannan viscosity and gel strength increased with the increase of the concentration of potassium ion,and also the determination of the modulus was displayed.The dynamic modulus was increased due to potassium ion,and konjac glucomannan's gelling was promoted.UV-visible scanning analysis showed that the absorption peak of K+-KGM system was in 200nm,however,compared to the single konjac glucomannan system,the system peak did not appear significant movement.Infrared scanning results showed characteristic absorption peak of K+-KGM did not occur significantly with the change;different complex absorption peaks appeared in the fingerprint area,and KGM molecules associating happened under the influence of K+,forming more hydrogen bonding and other weak interaction.Round dichroism analysis showed that in potassium ion solution,konjac glucomannan had a 186?207 nm wide distribution with positive cotton effect for peak.Konjac glucomannan had structural changes in potassium ions solution.(4)Solution properties and molecular chain conformation of konjac glucomannan under the influence of copper ions were discussed.Rheological properties research showed that under the influence of copper ion,KGM system still had the nature of non-newtonian fluid of shear thinning characteristic,and when 0.1 mol/L 16mL copper ion was added to 1%konjac glucomannan,the viscosity was influenced most.It showed that Cu2+-KGM system's dynamic rheological properties were stable.Through the ultraviolet spectrum,infrared spectral analysis and CD analysis it is known that copper ion was combined to konjac glucomannan molecules,and coordination function happened,resulting in the konjac glucomannan molecular structure of changes.