Studies On Mechanism And Characteristics Of Konjac Glucomannan Fraction/Carrageenan Blend System

Konjac glucomannan(KGM)is the main component of konjac,which is one kind of Araceae herbaceous plants.Through intermolecular hydrogen bonds,KGM formed strong synergyistic interaction with carrageenan,xanthan gum,chitosan,isolated soybean protein and some other polymers,which improved the rheology,gelling and film-forming properties of the system.What's more,recent studies showed the functional characteristics of KGM closely related to its molecular weight(Mw).Different Mw KGM,the functional properties were also different.Based on this,this parper take different Mw KGM fragment and carrageenan as material,prepared different KGM fragment/carrageenan blend system.The forming mechanisms of the blend systems were investigated.Then,the rheological and film-forming properties of the blend systems were studied.The main results are as follows:1.Ultraviolet(UV)and attenuated total reflection flourier transformed infrared(ATR-FTIR)spectroscopy results showed,the UV and ATR-FTIR spectrogram were similarly.Reducing the Mw of KGM fragment did not lead to the main functional group of blend system changed,neither new group formed,nor old group disappeared.Raman spectroscopy analysis result showed blend system at 2900 cm-1 has an absorption peak.It's CH vibration absorption peak.And with the reducing of KGM fragment Mw,the blend system abosorbtion increased at first,then reduced.This indicated appropriate reduce the molecular weight of KGM,conducived blend system to form more intermolecular hydrogen bonds.The interaction between KGM fraction and carrageenan enhance.X-ray diffraction analysis showed all KGM fragment/carrageenan blend systems belonged to amorphous material,but they are also existed microcrystalline structure.2.Rheology analysis showed KGM fragment/carrageenan blend solutions are pseudoplastic fluid.With the increasing of shear rate,the viscosity of solution decrease.And with the reduceing of KGM fragment Mw,the viscosity of solution decrease rapidly.With the reducing of total sugar concentration,the viscosity of solution decrease.With the content of carrageenan increase,the viscosity of solution increase at first,then decrease.With the adding of K+,the viscosity of solution increase obviously.However,adding Na+ and Ca2+,the viscosity of solution decrese a little.3.SEM observation showed appropriate decreasing the Mw of KGM fragment can make the blend film smoother.But decreasing the Mw further,the blend film will much cruder.This because appropriate decreasing the Mw of KGM fragment,can enhance the intermolecular hydrogen bonds between KGM and carrageenan.But KGM fragment Mw decreaseing further,the intermolecular hydrogen bonds between KGM and carrageenan become weaken.DSC analysis result showed range from-60? to 220?,KGM fragment/carrageenan blend film has only one absorption peak.This means KGM fragment and carrageenan are compatible.The respective structure of KGM fragment and carrageenan are disrupte.There are intermolecular interactions between KGM and carrageenan.Mechanical property tests showed,with the decreasing of KGM fragment Mw,the tensile strength of blend film increased at first but then decreased.In contrast,with the decreasing of KGM fragment Mw,the broken tensile rate and the moisture absorption of blend film decreased at first then increased.Hygroscopic property tests showed,with the decreasing of KGM fragment Mw,the moisture absorption of the blend film decreased at first but then increased.Water-resisting property tests showed,blend films has good short time water resistance,but with the time increasing,the water resistance of blend films decreased quickly.And reducing the Mw of KGM fragment,the water resistance of blend film increased at first but then decreased.Oil resistance property tests showed that all the blend films have good oil resistance.