Research Of Making The Chitosan/nanometer TiO₂ Antimicrobial Film And Its Capabilities

With the exaltation of the life level,the consumers like the high quality,nutrient and fresh food more and more.The growth of the microorganism not only is the important reason that makes product putrefied to change its character,and some microorganism possibly do harm to the human body.The antibacterial packing can kill or inhibit microorganism on food surface in the processing, storage,transportation and the treating processes,and also lengthen shelf life and security.In this text,chitosan and TiO₂ were composited to make a new kind of antibacterial films which were green and edible.Then,choosed the most appropriate process parameters of making films; comparative analyzed the differences between chitosan film and chitosan/TiO₂ antibacterial preservative film in sensory and mechanical properties,permeance properties of water vapor and atmosphere,and in antibacterial properties.At last,the film was used to pack strawberry,and its preservative effects was studied.Partâ… :Making and properties of chitosan film.Different chitosan film was made by different solution concentration of chitosan (0.5%,1%,1.5%,2%,2.5%)and by adding different amount of propanetriol(0%,0.4%,0.8%),and under different drying condition(dry under ambient temperature for 96h,under 20℃in loft drier for 48h,under 40℃in loft drier for 24h,under 60℃in loft drier for 12h,under 80℃in loft drier for 6h).Choosed the most appropriate process parameters of making the films through comparative analyzing the differences between chitosan film and chitosan/TiO₂ antibacterial preservative film in sensory properties,mechanical properties and permeance properties of water vapor and atmosphere. The result showed that the most appropriate process parameters were:solution concentration of chitosan:2%;adding amount of propanetriol:0.4%and dry condition was under 40℃in loft drier for 24h.Partâ…¡:Making and properties of chitosan/nanometer TiO₂ antibacterial preservative film.Making chitosan/nanometer TiO₂ antibacterial preservative film according to the most appropriate process parameters in Partâ… by adding different amount of TiO₂(0%,1%,2%,3%,4%). Through electron microscope we found that nanometer TiO₂ had good compatibility with chitosan solution.NanometerTiO₂ relatively uniformly distributed in the film although with few micro-aggregate which exist in the level of nanometer size.The research showed that:1)The film became more and more opacity with adding more nanometer TiO₂.2)Except adulteration rate of 3%, after adding nanometerTiO₂ all the film's water resistance(R),tensile strength in wet(σ_t(wet))and in dry(σ_t(dry))were increased,thereinto,l%increased most.3)With increasing the amount of nanometerTiO₂,film's antimicrobial activity to Escherichia coli and Staphylococcus aureus had a tendency of increase first then decrease,arid adulteration rate of 3%had the strongest.In summery, 1%is the best adulteration rate.Partâ…¢:Differences between chitosan film and chitosan/TiO₂ antibacterial preservative film in sensory and mechanical properties,permeance properties of water vapor and atmosphere,and in antibacterial property.The result showed that:1)Compared with chitosan film,chitosan/TiO₂ antibacterial preservative film'sσ_t(wet)increased 25.63%and R increased19.15%,which compensated the limitation of chitosan film inσ_t(wet),2)Chitosan film and chitosan/TiO₂ antibacterial preservative film had similar atmosphere properties and their rate of atmosphere property of CO₂ and O₂ were close to 4,which is very important to the freshness of fruits.3)Chitosan film's antimicrobial activity is strong and fast but chitosan/TiO₂ film's is stronger,faster and can last for a long time.After touched with bacterial liquor for 24h,the respective antimicrobial activity to Escherichia coli and Staphylococcus aureus were 98.3%and 95.5%,after 48h were 96.9%and 94.2%,besides,under glimmer chitosan/TiO₂ film still had good antimicrobial activity.Partâ…£:Compared the preservation effect of chitosan film and chitosan/TiO₂ antibacterial preservative film.The result showed that:Their effect were close and chitosan/TiO₂ antibacterial preservative film's was a little better.Used chitosan film and chitosan/TiO₂ antibacterial preservative film to pack strawberry can keep strawberry fresh for 5 days under ambient temperature and 12 days in cold storage with only little blet.