Assessment of the influence of amylose-LPC complexation on the extent of wheat starch digestibility by size-exclusion chromatography

Abstract

Amylose forms inclusion complexes with lysophosphatidylcholine (LPC), that decrease the susceptibility of amylose to amylase degradation. This study on the influence of complexation on starch susceptibility to amylase explains the nature of this protective effect. Wheat starch suspensions (9% w/w) containing 0.5–5% LPC were subjected to hydrolysis by porcine pancreatic α-amylase at 37°C for several digestion times. The digesta were analysed by size-exclusion chromatography (SEC). The molar mass distribution was closely dependent on the digestion time and amount of LPC. This study precisely demonstrates the alteration of the digestion profile of starch on a molecular level, influenced by amylose-LPC complexation; however the effect depends on the digestion time. During 15 and 30min digestion, inclusion complexes not only protect amylopectin in the initial hydrolysis stage, but also demonstrate lower susceptibility of the molecular amylose complexes to amylase hydrolysis. Digestion for 240min resulted in a lower oligosaccharide peak concentration, in the presence of a high LPC concentration, which is related to less degradation of complexed amylose fraction.