Studies On Preparation And Properties Of Films Based On Yam Starch

Yam starch,low cost and renewability,is the main ingredient of dry matter of yam.In this work,yam starch was used as raw material and the optimal conditions were determined to prepare yam starch films.Texture analyzer,scanning electron microscope,differential scanning calorimeter,infrared spectrometer and so on were applied to investigate the reaction mechanism between yam starch and plasticizers,enhancers,nanomaterials.The analysis of the chemical composition of yam starch used in this paper showed the following values expressed as dry base percentage:ash 0.35,lipids 0.45,protein 1.20 and starch 98.00.Thickness,tensile strength,elongation at break (E) and water vapor permeability were used as measures in four single factor experiments and orthogonal experiment.The yam starch films were prepared in optimal conditions as follows:starch concentration was 4.0%,glycerol concentration was 40%,drying temperature was 80?,pasting time was 30min.Propylene glycol,glycerol,diethylene glycol and ethylene glycol were used to study the influence on combination properties of yam starch films.The results showed that the plasticizers and yam starch could form strong hydrogen bond.Plasticizers could improve combination properties of yam starch films to some extent.Plasticizing effect depended on the number of hydrophilic groups and the size of molecular weight of plasticizers.The results showed that yam starch films plasticized by GLY processed the maximum value in E,WVP,moisture content and solubility and the minimum value in TS compared with the other plasticizers.FT-IR and thermal analysis results showed that plasticizer could form more stable network structure with yam starch than yam starch themselves and improve the thermal stability of yam starch films.SEM results showed that the section of plasticized yam starch films were rougher than pure yam films for compatibility.CMC,sodium alginate,gelatin and carrageenan were used to study the influence on yam starch films.The results showed that the enhancers could improve the mechanical properties of yam starch film and reduce the WVP and improve the solubility in water.FT-IR results showed that carrageenan,gelatin and sodium alginate form more stable hydrogen bond with yam starch than yam starch themselves.SEM analysis showed that adding enhancers could make the section of yam starch film smoother than before.SiO2,TiO2 and montmorillonite were studied on the influences of yam starch film.The results showed that the nanomaterials could form more compact network structure with yam starch than yam starch themselves and nanomaterials could improve the TS of yam starch films and reduce the E,water content and solubility of the films.DSC results showed that nanomaterials could enhance the thermal stability of yam starch film and improve the heat sealing.SEM analysis showed that adding nanomaterials made the section of yam starch film rough.