Performance Optimization Of Chitosan Starch Antibacterial Composite Membrane And Evaluation Of Fresh - Keeping Effect

The objective of this paper is to improve the physical and antimicrobial properties of the chitosan-starch composite films by adding different concentrations of polyvinyl alcohol, CaSO4, nanometer zinc oxide, exert its preferable preservation effect.The paper firstly optimizes the physical properties of chitosan- starch antibacterial composite film, including structural and mechanic properties.Add different concentration of polyvinyl alcohol, CaSO4 and nano zinc oxide in chitosan-starch composite film, then using the single factor test and orthogonal test to optimize the preparation conditions of the composite films. The mechanical properties, structure characteristics, transmission of light and water vapor transmission coefficient served as evaluated indexes. The experimental results show that the comprehensive performance of composite film is best when the polyvinyl alcohol concentration is 0.06%, CaSO4 is 0.09% and nano zinc oxide is 0.6%.Under the condition, the tensile strength of composite film reach 34%, water vapor transmission coefficient reach approximately 3g.cm/(cm2.S.Pa) and the light transmittance is more than 90%.Then we used E. coli, Staphylococcus aureus and Aspergillus Niger as test strains and evaluated the antibacterial performance of chitosan-starch antibacterial composite films. The results showed that composite films had good inhibitory function on the growth of the three kinds of bacteria when the concentration of nano zinc oxide was equal or more than 0.6%.The bacteriostatic circle diameter of the three kinds of bacteria are 24.47±0.5mm、23.43±0.65mm、18.03±2.73 mm, respectively.Finally, we evaluated the preservation effect of chitosan-starch antibacterial composite films after optimizing on red grape. After storage at 3±1 ℃for 60 days, the results showed that the weightlessness rate of blank test group(grapes do not do any processing) of red grape was more than 30%. The fresh fruit rate of grapes was only 18% and had lose edible value,A lot of mold grow on PE film groups(use PE films wrapping grapes) and the fresh fruit rate of grapes was only 20%. The weightlessness rate of chitosan-starch composite films group without nanometer zinc oxide(directly wrapping grapes) reached 23%, the surface of grapes shows slightly dry, and the fresh fruit rate of grapes was approximately 40%. The weightlessness rate of chitosan-starch composite films group with nano zinc oxide(directly wrapping grapes) was 18% and the fresh fruit rate of grapes was more than 60%.The results show that the optimization of chitosan-starch antibacterial composite films has perfect application value. The research has provided some interesting data to support the further development of chitosan-starch edible films.