Study On Gelatinization And Film Forming Characteristics Of High Amylose Corn Starch

High amylose corn starch has become one of the film forming material for if good film-forming and gelling properties,however,the high amylose corn starch granules were compactness which limited the its application in newly biodegradable material.It has been reported that the calcium chloride,as a starch solvent with high stability and environment-friendly,which can destroy the starch granule structure and increase the solubility in water under normal temperature.In addition,ultrasound wave can destroy the starch granules and increase the homogenous of film-forming dispersion.At present,there were less researches on the preparation of high amylose corn starch film treated by Ca Cl₂/ultrasound corresponding.The research used the high amylose corn starch as mainly film-forming material to prepare starch film and optimized the prepare technology by single factor and orthogonal experiment.We investigated the influences of Ca Cl₂content and ultrasound/Ca Cl₂corresponding treatment on genitalization and film-forming properties by rheology,mechanical,microscopic technology,DSC,X-ray,FTIR,water vapor permeability.A biodegradable bio-based packaging film with good mechanical properties and antibacterial ability was prepared.The main contents and research conclusions include:（1）Used the single factor and orthogonal experiment to determine the optimal technology conditions of high amylose corn starch film preparation:the starch content was 4%（w/w,based on film dispersion weight）,dry time was 10 h,dry temperature was45℃.After optimization,the tensile strength and elongation at break of film was 1.17MPa,37.06%respectively.（2）We investigated influence of the content of calcium chloride on gelatinization and film-forming of high amylose starch.At the stress rate range of 1～400 s^-1,the apparent viscosity of starch dispersion increased as the increasing of Ca Cl₂content.The mechanical test results showed that the tensile strength and elongation at break of starch film increased and then decreased as the increasing of Ca Cl₂content.The film has best mechanical properties when Ca Cl₂content was 8%（w/w）,and its tensile strength and elongation at break was 2.79 MPa,25.13%respectively.The results analysis of surface micromorphology showed the surface roughness decreased as the Ca Cl₂content increasing,and the film surface became smoother.（3）Utilized the ultrasound wave treated the Ca Cl₂/starch dispersion to prepare the starch film and used the single factor and orthogonal experiment to determine the optimal technology conditions of ultrasound:the ultrasound time was 60 min,the ultrasound power was 25%,and the ultrasound temperature was 70℃.After optimization,the tensile strength and elongation at break of film was 3.12 Mpa,84.24%respectively.（4）We investigated the influence of the ultrasound/Ca Cl₂treatment on gelatinization and film-forming properties of high amylose corn starch.The images of SEM and optical scope showed that the surface of HACS granules has cracks and less number of starch granules deformation after ultrasound or Ca Cl₂treatment.The results of X-ray,FTIR and DSC showed the crystallinity and short range orderliness of HACS obviously decreased,and the gelatinization temperature and enthalpy decreased after ultrasound/Ca Cl₂compared with ultrasound or Ca Cl₂.The rheological test results showed that the apparent viscosity was increased as the increasing of ultrasound power and time,and the starch in aqueous got better solution after lower power and long time of ultrasound treatment.The tensile strength and elongation at break increased,and the water vapor permeability index decreased.According to the above research,the reason of ultrasound/Ca Cl₂co-treatment increased the gelatinization and film-forming properties of HACS include:（a）Ca Cl₂destroys the starch granules inner structure,increased the solution of starch in aqueous.（b）Ultrasound wave loosen the starch granule surface,and increased the solution of starch in aqueous further.（c）During the process of film-forming,the chelation between starch chains and Ca²⁺ions increased the crosslinking of starch chains,inhibited the retrogradation of starch,enhanced the mechanical and barrier properties.（5）Calcium chloride in the film formation solution was removed by ion exchange method,and the natural antibacterial agent cinnamon essential oil was added to prepare high amylose corn starch composite film.Used the single factor and orthogonal experiment to determine the optimal content of polyvinyl alcohol,glycerin,cinnamon essential oil in composite film.After optimization,the tensile strength and elongation at break of film was 15.74 MPa,13.10%respectively.The results of antibacterial test indicated that the composite film showed obvious ability of inhibition,and the rate of antibacterial was 88.14%,86.15%respectively.