Restrictive Hydrolysis Of Octenylsuccinate Starch And The Stabilization Mechanism Of Its Emulsion

Octenylsuccinic anhydride modified starch(OS-starch) was prepared using acid and/or enzyme treatment to change the structure of starch molecule. The objective of this study was to elucidate the in?uence of OS-starch structure on the stability of oil-in-water emulsions.1、OS-starch was prepared by combining OSA modification of starch and β-amylase hydrolysis. Emulsion stability, droplet size distribution were studied to evaluate the emulsions, and the structure of OS-starch was analyzed using FT-IR, SEC and 1HNMR spectrum to understand the structure-function relationship. Results showed that with β-amylolysis, the average molecular weight of OS-starch decreased while degree of substitution(DS) and degree of branching(DB) increased. OS-starch prepared by using higher β-amylase concentration displayed a better emulsion stability and emulsions showed low apparent viscosity. But increasing the concentration of OS-starch led to big differences in viscosity, the more viscous of the emulsion, the better stability showed.2、After acid treatment, molecular wieght(Mw) of waxy maize starch decreased, paste viscosity of starch decreased. The X-ray diffraction reveal that reaction mainly occur at amorphous region, and esterification reaction also occured there, and lead the decrease of DS of OS-starch with hydrolysis-mild acidolysis. Appropriate acid-treated waxy maize starch was choosed for a further modification, the reasults showed that acid-treated OS-starch was more susceptible to β-amylase, the starch was hydrolyzed exhaustively at the lower enzyme concentration of 1.0%(w/w). After hydrolysis by β-amylase, DS and DB increased and Mw decreased what was consistent with the foremer results. Two OS-starches H-OSE and H-HOSE was used to make emulsion and showed similar emulsion stability.3、Physicochemical properties of M-HOSE(concentration of β-amylase was 0.5%, w/w), M-OSE(concentration of β-amylase was 1.0%, w/w), PG2000 and GA were compared. The clarity of M-OSE(10.4%) was higher than M-OSE(7.4%), and have better solubility. There was little effect of p H, ionic strength, and temperature on emulsions stabilized by GA or three modified starches, which was attributed to strong steric stabilization. After centrifugation, emulsions stabilized by PG2000 and GA remained stable, but oil layer of emulsion made by M-HOSE and M-OSE appeared. At 0.5: 9.5 mass ratio of modified starch to oil, M-HOSE showed the best stability, the photograph showed that M-HOSE remain stable, and the emulsion stabilized by GA has completely disrupted.