Effects of modification sequence on structures and properties ofhydroxypropylated and crosslinked waxy maize starch

摘要

The effects of modification sequence on chemical structures and physicochemical properties of hydroxypropylated (HP) and crosslinked (XL) waxy maize starch were investigated. The physicochemical properties, including pasting, gelling, and thermal properties, were studied. The chemical structures of dual-modified starches and their beta-limit dextrins were characterized with high-performance liquid chromatography. The HP-XL starch had higher Brabender viscosity than did the XL-HP starch at both pH 7 and 3; however, both showed similar gelling properties. Significantly higher onset and peak gelatinization temperatures, gelatinization enthalpy, and lower retrogradation were observed for the HP-XL starch. The HP-XL starch also exhibited significantly higher beta-amylolysis limit and higher content of low molecular weight saccharides in its isoamylase-debranched starch, suggesting its structure was more accessible to enzymatic attack than the XL-HP starch. Structural analyses revealed different distribution patterns of modifying groups between the two modified starches. The results indicate that the modification sequence altered the susceptibility to enzymes, changed the locations of substitution, and modified the physicochemical properties of the HP and XL waxy maize starches.