Study On Preparation And Performance Of Non-Crystal Crosslinked Octenyl Succinic Anhydride Modified Starch

Using non-crystal starch (N-NS) as raw material,sodium trimetaphosphate (STMP) and Octenyl Succinic Anhydride (OSA) as modification agent, non-crystal cross-linked octenyl succinic anhydride starch ester (N-COSAS) was synthesized by one-step process(N-1-COSAS) and three-step process(N-3-COSAS), respectively. The influences of amount of STMP, crosslinking time, crosslinking temperature, crosslinking pH, esterification time, esterification temperature and esterification pH on the physicochemical properties of the two pruducts such as degree of substitution(CP), combined phosphorus(DS), intrinsic viscosity(η), transparency, and blue value were comparatively studied by single factor experiment and orthogonal experiment. The functional groups, morphology, crystal structure and thermostability of the products were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction and differential scanning calorimetry (DSC), respectively.The physicochemical measurement showed that the CP, DS and η for N-1-COSAS were greater than those for N-3-COSAS. The phenomenon of shear thinning for N-COSAS paste with some thixotropy was in accordance with the exponential curve change rule, and its relationship with temperature was conformed to Arrhenius equation. Meanwhile, the transparency, apparent viscosity and melting point of N-COSAS were lower than those of native starch (NS), and the anticoagulation for N-COSAS was weaker than that of NS. But the acid resistance and alkali resistance for N-COSAS were better than those of NS. Moreover, the efficiently technological conditions for preparation of low viscosity N-COSAS by one-step process were that:the amount of STMP1.5%(based on the mass of starch), cross-linking time4h, cross-linking temperature45℃, cross-linking pH10.0, esterification time3h, esterification temperature35℃, and esterification pH8.5.The structure test show that a new absorption peak at about1600cm-1appeared in the FT-IR spectrum of the two starch esters, which demonstrated that the esterification reaction were occurred in the two processes. The crystallinity of N-COSAS with a V-type crystalline structure was lower than that of NS, and the dispersion degree of diffraction peaks for N-COSAS was similar to those of N-NS. The particle surfaces of N-COSAS were rougher than that of N-NS. In addition, thermostabilities of N-COSAS were better than that of N-NS.