Preparation And Application Of Chitosan-based Antibacterial Preservative Film

Chitosan was a kind of natural biological macromolecule,which had very good film-forming properties,however its application was limited due to its narrow antibacterial range and poor antimicrobial ability.The chitosan-based antibacterial film,which adding a certain amount of antibacterial,can achieve the purpose of antibacterial and extending the shelf life.The chitosan-based antibacterial film was optimized by the comprehensive performance of the film as an index,and various performance parameters of the optimized film were analyzed.The optimized film was used in the storage and preservation test of snap beans to investigate the effect of optimized chitosan-based antibacterial film on the storage and preservation of snap bean.The results are as follows:1 The influence of adding amount of namycin and adding amount of nano-TiO₂ and stirring temperature on antibacterial activity of chitosan-based composite film fluid was investigated,Yeast,Aspergillus niger,Staphylococcus aureus and Shigella as the bacteriostatic objects.The optimum conditions for the chitosan-based compounding solution were obtained by response surface methed as follows:the dosage of namamycin was 0.075%,the dosage of nano-TiO₂ was0.08%,and the stirring temperature was 50?,bacteriostasis circle diameter on Yeast was?36.03±0.70?mm,bacteriostasis circle diameter on Aspergillus niger was?44.73±0.59?mm,bacteriostasis circle diameter on Staphylococcus aureus was?27.21±0.62?mm and bacteriostasis circle diameter of Shigella was?27.71±0.51?mm.2 Chitosan was used as the base material,natamycin and nano-TiO₂ were added as antibacterial agents,glycerol was used as plasticizer to prepare chitosan-based antibacterial preservative film.The optimization of single factor and response surface was carried out with the tensile strength and elongation at break as the main evaluation indexes,and the optimum technological conditions for chitosan-based composite film were as follows:The addition of glycerol was 0.8%,the amount of polyvinyl alcohol was 0.75%,the addition of nanamycin was0.075%,and the addition of nano-TiO₂ was 0.08%?mass/volume ratio?.Under this condition,the performance parameters of the chitosan-based antimicrobial cling film were as follows:the tensile strength was?12.37±0.76?MPa,the elongation at break was?34.08±0.87?%,the film thickness was?0.65±0.45?mm,the moisture permeability was?563±1.78?g/?m²·24h?,the light transmittance was?57.4±0.96?%,and the haze was?90.8±0.93?%.The showed that the chitosan-based antimicrobial cling film showed a smooth,continuous,detailed structure by observation of scanning electron microscopy?SEM?and infrared spectroscopy?FTIR?,chitosan hasgoodcompatibilitywithpolyvinylalcohol,natamycinandnano-TiO₂.The Thermogravimetric analysis results showed that the chitosan-based antibacterial cling film had good thermal stability.3 In order to test the practical fresh-keeping effect of chitosan-based antibacterial cling film,the snap beans were used as test materials for storage and preservation,and the storage effect of chitosan-based antibacterial cling film on the snap beans was investigated.The results showed that:the chitosan-based antibacterial cling film can effectively reduce the weight loss rate and rot rate of the snap beans,delay the reducing of superoxid dismutase?SOD?and the decrease of Vc content and sugar content,inhibit the increas of respiratory intensity,delay the production of respiratory peaks,effectively inhibit the increase of malondialdehyde?MDA?content in snap beans,decrease the rate of yellowing,delay the nutrient loss of snap beans,and prolong the storage time at the temperature of 10°C and the relative humidity of 65%.