Effects Of Natural Fermentation And Sodium Alginate Addition On The Structure And Properties Of Wheat Starch

Wheat is a kind of nutritious and healthy cereal which is rich in starch,protein and ash since the beginning of civilization.It is well known that the quality characteristics of wheat-based foods are largely related to structure of starch during food processing.When heated,starch absorbs water,swells,and forms a paste,which plays an important role in starch-based products and also allows its wide use as a thickening agent,stabilizer,and texturizer in food and non-food industries.However,native starch has many innate disadvantages,such as syneresis,retrogradation,and textural change Therefore,this work investigated changes of multi-scale structures fermented starch,in additions,the changes of multi-scale structures and retrogradation properties of native:wheat starches(NS)modified by fermentation and by addition of sodium alginate(AG).The change of multi-scale structure in wheat starch between fermented and adding sodium alginate is as follows:(1)The results showed that fermentation reduced weight-average molecular weight(Mw)and slightly eroded the starch granule surface.An obvious increase in relative crystallinity from X-ray diffraction was observed in all fermented starch(39.3 8-42.27%)when compared with native starch(37.15%).Data from small angle X-ray scattering revealed that fermentation increased the crystalline layer and decreased the amorphous region of the starch granules.The intensity of absorption related to hydrogen bonding by FT=IR(3,000-3,600 cm-1)also increased in fermented starch.The rapid viscosity analysis results showed that fermented starch had a lower peak viscosity and final viscosity,and a lower setback value than native starch.The present results reveal that fermentation is an effective method to modify wheat starch and suggest its potential to improve the quality of starch-based foods.(2)This work investigated changes of multi-scale structures and retrogradation properties of native wheat starches(NS)modified by fermentation and by addition of sodium alginate(AG).AG adhered on the surface of NS granules.The AG adhesions were more abundant in fermented starch(FS)than in NS.Compared with addition of AG alone,dual modification by fermentation and AG together showed greater effect on increase of the weight-average molecular weight and reduction of the relative crystallinity and double helix degree of NS.Small angle X-ray diffraction revealed that dual modification increased the amorphous region of NS more significantly than did single AG treatment.(3)Additionally,dual modification greatly slowed the increase of relative crystallinity,and enthalpy(?H)of NS paste during storage.Present study proposed that fermentation combined with AG changed multi-scale structures and retarded the retrogradation of NS by increasing interaction of AG with NS in the amorphous region.