Esterification Of Canna Starch And The Research Of Its Application Characteristics

Canna starch, a kind of non-staple food crops, has advantages in high amylose content and high molecular weights, has attracted many researchers. This paper was aimed to explore the method and feasibility of using canna starch as raw material to prepare starch-based composites, which will enrich the comprehensive utilization and high value-added conversion of canna starch.In the subject, cetate/polyvinyl alcohol (SA/PVA) composite films were prepared through esterification modification of high-amylose canna. The structures of esterified starch and SA/PVA composite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD), scanning electron microscope (SEM) and so on. The viscosity, freeze-thaw stability, transparency and sink coagulation performance of the esterified starch were also tested, as well as the mechanical property, water absorbency and light transmission of the SA/PVA composite film.The results of XRD showed that the crystal structure of canna starch belonged to A type, and the esterification modification did not change its original crystal with a exception of reduced crystallinity. SEM images showed that the canna starch was oval polyhedron, and esterification destroyed the surface structure of starch particles, making them stripped or eroded to be smaller.Additionally, we found that esterification reduced the start paste viscosity of starch ester effectively. With increasing of degree of substitution, freeze-thaw stability, light transmittance and sink coagulation property of starch were enhanced, and the starch acetate obtained the best performance.A series of SA/PVA composite films were prepared by changing four factors of PVA, additive, antibacterial agent content and blending time. Their mechanical properties, water absorbency, light transmittance and antibacterial performance were compared. The results showed that the optimal preparation condition of SA/PVA composite film was that:PVA 25wt%, urea 3wt%, potassium sorbate 0.6wt%, blending time 1.5 h.SEM analysis found that with the increase of PVA content, the surface of SA/PVA composite film was smoother, denser, and the gap of cross section and wrinkle were gradually reduced, tending to be smoother. The result indicated that the compatibility of PVA and starch was improved, and hence improved the film-forming ability and mechanical property of starch ester.Antibacterial experiment results showed that the increase of antibacterial agent concentration improved the antibacterial effect on both coli and staphylococcus aureus, especially the effect on escherichia. Taking all aspects of performance of the composite film into account, the amount of antimicrobial base was 0.6wt%.