To improve the yield and stability of VII-type cornstarch-lauric acid complexes and inhibit the digestibility of starch, debranched cornstarch was used to complex with lauric acid under a low complexation temperature and a high complexation temperature (DSL30 and DSL90). Debranching treatment raised the yield of the complexes and the melting enthalpy, which reached 51.4% and 14.26 J/g for the complex DSL90, respectively. Complexes formed at high complexation temperature showed high melting temperature ranged in 102.71 °C-120.30 °C, indicating high thermal stability. As the complexation temperature increased from 30 °C to 90 °C, the complexes transformed from VI-type to VII-type. The combination of debranching treatment and increasing complexation temperature decreased the in vitro digestibility of the complexes. The highest resistant starch content was found in the complex DSL90, which also exhibited a lamellar structure under the scanning electron microscopy. The root mean square deviation under the molecular dynamics simulations of the complexes was lower than that of single amylose, suggesting that the complexation with lauric acid could keep the conformation of the amylose chain stable. Debranching treatment combined with a high complexation temperature may be used as an applicable method to prepare VII-type starch-fatty acid complexes with high stability.
Keywords: Complexation temperature; Debranching treatment; Molecular dynamics simulation.
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