Supernatant starch fraction of corn starch and its emulsifying ability: Effect of the amylose content

Abstract

Corn starches with different amylose contents (2.0%, 27.5%, and 49.1%) were gelatinized and centrifuged to obtain the supernatants. It was found that the starch fractions in the three supernatants might be amylose and have similar molecular weight. However, the solid content in the supernatants was in the order of normal corn starch > high-amylose corn starch > waxy corn starch. Contact angle analysis indicated that these supernatant starch fractions had affinity for both water and oil, thus displaying emulsifying ability. Subsequently, the supernatants were used to prepare oil-in-water emulsions. All emulsions had good ionic, pH and thermal stability, while their storage stability was in the order of normal corn starch emulsion > high-amylose corn starch emulsion > waxy corn starch emulsion. In addition, no starch-lipid complex was detected in the emulsion by DSC and XRD analysis. These results suggested that the supernatant starch fractions had emulsifying ability and the stability of obtained emulsions depended on the solid content of the supernatants.