Preparation And Characterization Of Starch Based Film Containing Cinnamaldehyde/Cyclodextrin Complex

Food-borne diseases and environmental pollution caused by petroleum based nondegradable packaging materials have attracted widespread attention in recent years.The use of biological materials to prepare bio-based active packaging has become a new trend in the food packaging industry.In the paper,high amylose corn starch and konjac glucomannan were used as the main film-forming materials and the effect of preparation process on the performance of high amylose corn starch/konjac glucomannan composite film was investigate.The cinnamaldehyde/cyclodextrin complex was incorporate into the composite film to prepare a new biodegradable bioactive packaging film with outstanding mechanical,barrier and antibacterial properties.The main contents and conclusions were as follows:(1)The optimum conditions of the preparation of high amylose corn starch/konjac glucomannan composite film were determined by single-factor and orthogonal experiment: the high amylose corn starch concentration was 2.6%,the amount of konjac glucomannan was 0.4%,the plasticizer glycerol dosage was 1.5%,the amount of filmforming solution was 100 m L,and the drying temperature was 50 °C.The tensile strength of the composite film was 14.324 MPa and the elongation at break was 53.11% after optimization.(2)The effects of ?-cyclodextrin and cinnamaldehyde/?-cyclodextrin complex on the mechanical and barrier properties of the high amylose corn starch/konjac glucomannan composite film were investigated.The thickness of the composite films increased gradually with the addition of ?-cyclodextrin and its complex.The tensile strength values of the composite films were improved and achieved the highest values when the contents of ?-cyclodextrin and the complex were 1.5% and 2.0% respectively,which were 13.766 MPa and 23.881 MPa,respectively.The incorporation of ?-cyclodextrin and its complex also reduced the water content in the composite films and improved the water vapor resistance.The composite films containing 1.5% of ?-cyclodextrin and 2.0% of the complex showed the flattest and compact surfaces.(3)The effects of ?-cyclodextrin and cinnamaldehyde/?-cyclodextrin complex on the intermolecular interaction between the two polysaccharides in the composite film were discussed using X-ray diffraction,Fourier transform infrared spectroscopy and thermal stability analyses.The crystallinity and proportions of short-range order structure of starch in the composite films decreased after the incorporation of ?-cyclodextrin and the complex.The decomposition temperatures of the composite films increased from309 °C to 337 °C and 348 °C,respectively.The influence of ?-cyclodextrin and its complex on the interaction between polysaccharide molecules was mainly in two ways(a)the scattering into the film-forming solution promoted the uniform dispersion of the components under stirring,which provided opportunities for the polysaccharide chains to get close to each other;(b)the exclusion and aggregation in the film-forming process,accelerating the high amylose corn starch to interact with konjac glucomannan more compactly.The hydrophobic effect and low compatibility between the cinnamaldehyde/?-cyclodextrin complex and the polysaccharide system promoted the dispersion and association of polysaccharide molecules better than ?-cyclodextrin.(4)The controlled release of cinnamaldehyde in the composite film containing cinnamaldehyde/?-cyclodextrin complex and the antibacterial ability of the film on Staphylococcus aureus and Escherichia coli were evaluated.The results showed that the controlled release effect of ?-cyclodextrin on cinnamaldehyde was the best when the addition amount of the complex was 2.0%.High temperature and high humidity environment accelerated the diffusion and release of cinnamaldehyde.The inhibition zone appeared in the Staphylococcus aureus agar medium when the addition amount of the complex exceeded 2.0%,which indicated that the antibacterial films had obvious inhibitory effects against of Staphylococcus aureus.The reproduction of Staphylococcus aureus and Escherichia coli after inoculating on the composite films were completely inhibited when the complex content above 2.0% and 2.5%.The fresh-keeping effect of the antibacterial composite film on bread was investigated.The commercially available polyethylene film as a control.The composite packaging film containing 2.0% of cinnamaldehyde/?-cyclodextrin complex can effectively inhibit the growth of mold in bread compared with the polyethylene film.