Octenyl Succinic-Modified Starch Complexes with Dipalmitoyl Glycerol Isomers

Starch-lipid complexes are generating great research interest due to their promising health benefits. However, there remains a big challenge for preparing typical V-type crystalline starch-diacylglycerol or triacylglycerol complexes. In this study, two diacylglycerol (DAG) isomers ((1,2 dipalmitoyl glycerol; 1,2 DPG) and (1,3 dipalmitoyl glycerol; 1,3 DPG)) were used to prepare the V-type crystalline starch-lipid complexes and to understand the role of molecular conformation in the formation of starch-DAG complexes using a modified previous protocol in which the complexing parameters were optimized. Multiple structural analyses showed that octenyl succinic anhydride (OSA)-maize starch (MS) interacted with 1,2 DPG and 1,3 DPG to form the typical V-type crystalline complexes, with more single helical complexes and their V-type crystalline aggregates formed between OSAMS and 1,2 DPG than between OSAMS and 1,3 DPG. Molecular dynamics simulations predicted that the two alkyl chains of 1,2 DPG were wrapped together into the amylose helices, whereas those of 1,3 DPG interacted separately. The encapsulation of the two alkyl chains of 1,2 DPG by AM helices together is proposed to enable the complexes to stack more readily into crystalline aggregates. This study has significance for the preparation of starch-DAG complexes with desirable functional properties.