Effects Of Gellan Gum On Properties Of Potato Starch And Study On Their Interaction

Starch is abundant in nature,and possesses extensive applications in food fields.However,native starch does not satisfy the requirements of production because of its instability under heat and acidic conditions.Starch-hydrocolloids systems often improve the properties of native starch and are used in food.In the present study,the effects of gellan gum on properties of potato starch were investigated by physical blending potato starch(PS)with gellan gum(GG).On the basis a guiding significance for the actual production can be found.This study investigated the effects of gellan gum on pasting and rheological properties of potato starch firstly.Rapid viscosity analyzer(RVA)showed that gellan gum significantly changed the pasting curves of potato starch.Gellan gu m caused a significant decrease in peak viscosity and breakdown values at concentration of gellan gum ? 3.0%.However,gellan gum caused a slight increase in peak viscosity and breakdown values at concentration of gellan gum ? 3.0%.Steady rheological measurements results showed that the potato starch and potato starch-gellan gum mixtures exhibited shear-thinning flow behavior.Dynamic rheological measurements revealed that the G' and G'' of the mixtures decreased with the increasing of gellan gum concentration when the addition levels of gellan gum were lower than 3.0%,but increased with the increasing of gellan gum concentration.Concentration of leached amylose measurements results showed gellan gum could caused a decrease of leached amylose.Furthermore,this study investigated the effects of gellan gum on microstructure,starch granule swelling and the mobility of the water molecule.The results showed that the addition of gellan gum caused T2 to decrease,as well as the mobility of the water molecule was decreased by adding gellan gum.It was a reason that the starch granules became less swollen in the mixtures.The scanning electron microscope(SEM)observation of samples confirmed that the starch granules appeared prominently coated with gellan gum,which made some starch granules unbroken.The effect of gellan gum on the retrogradation of potato starch was investigated by means of rotational rheometer,differential scanning calorimetry(DSC),X-ray diffraction(XRD)and Low Field-Nuclear Magnetic Resonance(LF-NMR).DSC gelatinization thermograms and XRD(stored for 0 d)results also proved that gellan gum could suppress the gelatinization of potato starch.The dynamic time sweep of samples suggested that the addition of gellan gum promoted the short-term retrogradation of potato starch.DSC retrogradation curves showed that gellan gum increased the retrogradation enthalpy of amylopectin.XRD(stored for 0 d and 7 d)results showed that recrystallinity of potato starch increased 9.84%,but that of mixtures increased 9.97%,10.71%,11.24% and 11.80% respectively with the increase of gellan gum concentration from 0.4% to 3.0%.LF-NMR data indicated that the T23 signal could only be observed in the mixtures.Meanwhile,retrogradation measurements intuitively proved that gellan gum promoted the retrogradation of potato starch.However,mixtures could form gel at low concentration of potato starch with calcium ions.In addition,gellan gum could also improve texture and water holding capacity of gel with calcium ions.The paper investigated the effect of gellan gum on films' properties.Fourier transform infrared spectroscopy(FTIR)and SEM were used to highlight the starch based films.The results suggested that potato starch and gellan gum had excellent blend miscibility.Moisture sorption isotherms were also studied and Guhhenheim-Anderson-de Boer(GAB)sorption models were tested to fit the experimental data.The monolayer moisture content(M0),the sorption parameters,increased initially and then decreased with the increase of gellan gum concentration.The addition of gellan gum to potato starch decreased the elongation at break(EAB),but improved the tensile strength(TS),values of water vapor permeability(WVP)and oil permeability(OP)leading to an improvement of barrier properties of the films.