Effects Of Artemisia Annua Polysaccharides On Gelatinization And Aging Characteristics Of Wheat Starch

Wheat starch(WS)is an important natural plant resource with unique structure,and it has been widely applied as thickener,stabilizer and gelling agent during food processing.To improve the anti-aging property of wheat starch,ASKP and its different structural components(60P,60S)and different molecular weight components(60P1,60P2)was added to prepare the complex system.RVA,DSC,TPA,XRD,FT-IR,LF-NMR and other techniques were used to study the effects of ASKP with different structures and molecular weights on the gelatinization and retrogradation properties of wheat starch and its mechanism.The main results are as follows:(1)ASKP is a kind of natural plant heteropolysaccharide with high viscosity,mainly composed of xylose,arabinose,mannose,glucose and galactose.RVA,DSC,TPA and XRD results displayed that,with the addition of ASKP,the peak viscosity,setback values,gelatinization enthalpy of wheat starch all increased,the retrogradation enthaphy,hardness of starch gel,and relative crystallinity of short-term storage increased,while the retrogradation enthaphy,gel hardness,and relative crystallinity of long-term storage showed a downward trend.Results of FT-IR revealed that ASKP could promote the water retention and intermolecular hydrogen bonding formation.With the addition of ASKP,the spin-spin relaxation time(T2)measured by LF-NMR decreased from 358.47 ms to 274.15 ms,indicating that ASKP could improve the water retention ability of starch paste.(2)60P is mainly composed of xylose,arabinose,glucose,galactose and rhamnose.60P is a high-molecular-weight component separated from ASKP,its main chain is connected by xylan,and its branched chains mainly include arabinose and uronic acid.After 60P was added,the peak viscosity,setback values,and gelatinization enthalpy of wheat starch all increased,the retrogradation enthaphy and gel hardness of short-term storage increased,while the retrogradation enthaphy and gel hardness of long-term storage showed a downward trend.G' value increased with the addition of 60P.With the addition of 60P increased,the relative crystallinity of wheat starch during short-term storage increased from 1.05%to 2.70%,while that during long-term storage decreased from 3.51%to 3.48%.60S is mainly composed of glucose,mannose,galactose and arabinose.60S is a low-molecular-weight component separated from ASKP,and the structure contains acetyl group.After 60S was added,the peak viscosity,setback values,gelatinization enthalpy,retrogradation enthaphy,gel hardness,and relative crystallinity of wheat starch all decreased.G' value decreased with the addition of 60S.FT-IR results demonstrated that 60P had stronger effects than 60S to promote water retention and intermolecular hydrogen bonding formation.In summary,60P played a leading role in ASKP on the gelatinization and retrogradation properties of WS.(3)Xylanase was used to treat 60P(Mw:551 kDa)by enzymatic hydrolysis,and two polysaccharides with lower molecular weight(60P1(Mw:250 kDa)and 60P2(Mw:120 kDa))were obtained without changing the main chain structure.The peak viscosity,setback values,and gelatinization enthalpy of wheat starch increased with the addition of 60P1.With the addition of 60P1,the retrogradation enthaphy and gel hardness of wheat starch increased during short-term storage,while the retrogradation enthaphy and gel hardness showed a downward trend during long-term storage.With the addition of 60P1 increased,the relative crystallinity of wheat starch during short-term storage increased from 1.05%to 2.23%,while that during lon g-term storage decreased from 3.51%to 2.74%.With the addition of 60P2,the peak viscosity,setback values,gelatinization enthalpy,retrogradation enthaphy,gel hardness,and relative crystallinity of wheat starch all decreased.With the decrease of molecular weight,the effect of 60P component on the gelatinization and retrogradation properties of wheat starch gradually approached to the effect of 60S.