Abstract: In order to extend the shelf life of ginger and obtain a composite coating film with excellent antibacterial and preservative properties, composite coatings of chitosan (CS) and konjac glucomannan (KGM) were prepared by casting method, and modified by gingerin and in situ synthesized nano-SiOx. The composite coatings were characterized by scanning electronic microscopy, X-Ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) and their physicochemical properties were measured. The influence of the microstructure and physiochemical properties of the composite coatings on their preservation effect on ginger was explored. The results showed that after the addition of gingerin, the elongation at break of the composite coating was increased from 30.70% to 34.81% (P < 0.05), and tensile strength from 17.97 to 24.41 MPa (P < 0.05). While O2, CO2 and light transmittance did not change significantly (P > 0.05), water vapor transmittance was significantly reduced (P < 0.05). After subsequent addition of in situ synthesized nano-silicon based oxide (SiOx), the elongation at break of the composite coating film was increased to 38.82%, and tensile strength to 28.72 MPa (P < 0.05). Both O2 and CO2 transmittance increased significantly (P < 0.05), and light transmittance decreased slightly, whereas water vapor transmission rate did not change significantly (P > 0.05). KGM/CS composite coatings reduced mass loss, the contents of total phenolic compounds and flavonoids in ginger rhizomes during storage. Meanwhile, KGM/CS inhibited the decrease of soluble sugar, and extended the shelf-life. The composite coatings co-modified by gingerin and in situ synthesized nano-SiOx had better preservation properties as compared to either modifier alone.

Key words: ginger, chitosan, konjac glycosan, composite coating, preservation