The physicochemical properties of swelled maize starch granules complexed with lauric acid

Starch–lipid complexes were prepared using lauric acid (LA) and three varieties of maize starches differing in amylose content i.e. waxy maize starch (WMS), normal maize starch (NMS) and high amylose maize starch (Hylon V). Starch suspensions were heated below the pasting temperature and then complexed. Effects of amylose content, incubation temperature and LA on the physicochemical properties of swelled starch–LA complexes were investigated. Swelled Hylon V and NMS were easy to form starch–LA complex. Lipid content revealed that the increasing incubation temperature and high amylose content can improve the formation of starch–LA complex. Light microscopy displayed that the Hylon V-LA and NMS–LA complex incubated at higher temperature had irregularly-shaped fragments with strong birefringence. X-ray diffraction pattern of Hylon V-LA and NMS–LA complex changed to V-type polymorphs except for NMS incubated at low temperature (60 °C). The relative crystallinity was depended on the amylose content and incubation temperature. Synergistic effects on thermal properties were observed when the starch–LA complex was prepared under higher incubation temperature and with high amylose content.