Biocatalytic Synthesis and Characterization of Starch Ferulate Based on Ultrasonic Pretreatment of Substrate

To improve the hydrophobicity and biological activity of corn starch, starch ferulate was prepared by Novozym 435 lipase catalyzed transesterification of ultrasonic pretreated corn starch and ethyl ferulate. The ferulic acylation of starch was confirmed by UV and Fourier transform infrared spectroscopy (FT-IR). Starch ferulate was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). In addition, the hygroscopicity and free radical scavenging ability of esterified starch (ES) were evaluated. In the results, the maximum degree of substitution (DS) of ES was 0.0728 under the optimal ultrasonic pretreatment conditions, which was much higher than that of 0.0142 without ultrasonic pretreatment. The XRD and DSC analysis showed that ferulic acylation destroyed the crystalline structure of corn starch to a certain extent. Moreover, ferulic acylation can improve the hydrophobicity and free radical scavenging ability of starch. In conclusion, ES obtained with ultrasonic pretreatment followed by enzyme catalysis can improve physical and chemical properties of starch. Ultrasonic provides an effective method for synthesizing high-quality modified starch and lays a theoretical foundation for expanding the application of corn starch.