Preparation And Properties Of Gelatin/chitosan Antimicrobial Food Packaging Film

With the concerns about food safety and human health,the development of antibacterial food packaging has gradually become the hot issues.Biofilms based on natural biomacromolecules?such as gelatin,cellulose,chitosan?have great potential in food packaging application because of the low cost,biocompatibility,biodegradation and processability.Generally,films with single component cannot fully meet the requirements of food packaging due to the weak mechanical properties and low block to O₂ and water.Hence,composite films with multicomponents are normally used to solve the problems.However,the low antibacterial properties of natural-biomacromolecule based films limit the application in antibacterial food packaging.Capsaicin,the extract of red chili,is a common food coloring and flavoring agent with strong antibacterial properties and significant inhibition against Gram bacteria and fungi.The interaction between capsaicin and natural biomacromolecules can endow excellent antibacterial property to natural-biomacromolecule based films.Herein,the gelatin/chitosan composite films were taken as the substrate with capsaicin embedded inside the composite films to promote the mechanical properties and physicochemical properties.The antibacterial performance of different loading capsaicin against E.coli as the representative bacteria was investigated.The main research contents and results are showed as follows:?1?The physicochemical properties and antimicrobial properties of gelatin/chitosan composite films were studied by embedding capsaicin.The optimum film forming process of gelatin/chitosan was determined by orthogonal test.The optimum preparation conditions were showed as follows:chitosan concentration of 1%?g/mL?,chitosan to gelatin volume ratio to be 1:1,glycerol of20%?g/g?and gelatin concentration of 3%?g/mL?.The capsaicin/gelatin/chitosan composite films were prepared by the mixture of ethanol and water.Scanning Electron Microscope?SEM?results showed that capsaicin separated out in the composite film to form a rough surface and caused loose inner structures without the change of the thickness of the films.Mechanical tests showed that with the increasing contents of capsaicin,the tensile strength of the composite films increased with decreased elongation at break.Meanwhile,the water vapor permeability,the water solubility and the water content of the composite films all decreased.The hydrophobicity of the composite films increased with the addition of capsaicin.The UV-vis spectra indicated the excellent transparency and UV block properties.The standard colony counting method results exhibited good inhibition against E.coli and more than 4%capsaicin in the films could achieve excellent antibacterial activity.?2?The physicochemical properties and antimicrobial properties of gelatin/chitosan composite films were studied by the incorporation of capsaicin-loaded Fe ^?-HMOF-5.The hollow Fe ^?-HMOF-5 was successfully prepared by one-pot solvothermal method.The capsaicin was loaded into the Fe^?-HMOF-5 by immersion and absorption.XRD patterns confirmed the crystal structure of Fe ^?-HMOF-5.The capsaicin-loaded Fe ^?-HMOF-5/gelatin/chitosan composite films were prepared by casting method.Transmission Electron Microscopy?TEM?images showed the successful incorporation of capsaicin.SEM images exhibited that capsaicin-loaded Fe^?-HMOF-5 did not change the inner structures of capsaicin-loaded Fe ^?-HMOF-5/gelatin/chitosan composite films.The mechanical tests indicated that with the increasing contents of capsaicin-loaded Fe ^?-HMOF-5,the tensile strength of the composite films increased with decreased elongation at break.In the meantime,the hydrophilicity of capsaicin-loaded Fe ^?-HMOF-5 increased the water vapor permeability and the water solubility of the composite films.Compared with the composite films with imbedded capsaicin,the capsaicin-loaded Fe ^?-HMOF-5 composite films were more hydrophilic.The UV-vis spectra indicated good transparency and UV block properties.The standard colony counting method results exhibited excellent antibacterial activity against E.coli.This study proved that capsaicin-loaded Fe ^?-HMOF-5 was an effective antibacterial agent.