The effect of enzymatic pretreatments on subsequent octenyl succinic anhydride modifications of cornstarch

Cornstarch granules were allowed to react with a-amylase and then esterified with octenyl succinic anhydride (OSA). The paste properties and the distribution of octenyl succinate (OS) groups of OS-starch granule were studied. Results show that the alpha-amylase pretreatments significantly decreased the degree of substitution (DS) of OS-starch compare with a non-pretreated control group, while the retrogradation properties, freeze-thaw stability and shearing resistant stability of alpha-amylase pretreated OS-starch didn't change markedly. Enzymatic pretreatment appears to influence the distribution of the OS groups from being mostly on the surface and amorphous part of the starch granules to being in the inner amorphous and crystalline regions of the granules, as shown by X-ray photoelectron spectroscopy (XPS) and lintnerisation studies. (C) 2009 Elsevier Ltd. All rights reserved.