Preparation, Properties And Application Of Chitosan/Soy Protein Isolate Composite Films

Plastic was the preferred choice of packaging materials that had the advantages of low price, high strength and corrosion resistance. But plastic packaging films not easyed to degraded and causeed environmental problem, such as white pollution. The degradable packageing composite materials research and development is necessary. Chitosan(CS) has good properties of non-toxic, side-effect free, film-forming, biodegradable and antibacterial. Soybean protein isolated(SPI) has the advantage of high solubility, extensive sources, low price, biodegradable and film-forming.In this thesis, firstly, CS and SPI were used as substrate, glycerol as plasticizer, CS/SPI composite film was prepared by solution blending method. Secondly, the CS/SPI composite film was cross-linked by sodium citrate and ferulic acid. The influence of sodium citrate and ferulic acid on packing properties of CS/SPI composite film was evaluated. Then Nisin and tea polyphenols(TP) were used as functional additives, Nisin-CS/SPI cross-linked composite film and TP-CS/SPI cross-linked composite film were prepared through solution blending method. The prepared CS/SPI cross-linked composite film, Nisin-CS/SPI cross-linked composite film and TP-CS/SPI cross-linked composite film were applied to storages of beef.1. With CS and SPI as material, glycerin as plasticizer, CS/SPI composite film were prepared, the effects of SPI content and glycerol content on visual, mechanical, water solubility and water vapor permeability of the films were investigated. The results showed that SPI content was 20% and glycerin dosage of 1%(v/v), the CS/SPI composite film had good properties.2. Sodium citrate and ferulic acid as cross-linker, CS/SPI cross-linked composite film was prepared. The influence of sodium citrate and ferulic acid on the packing properties of CS/SPI cross-linked composite film was evaluated. The results showed that the molecular interaction of composite film was increased by sodium citrate and ferulic acid. The mechanical properties, water vapor barrier properties and antioxidant property of CS/SPI composite film was improved.The CS/SPI composite film of the DPPH radical scavenging activity was enhanced by 1.72 times when sodium citrate content was 0.03%(w/v). The water solubility and water vapor permeability of composite film was lowest when ferulic acid content was 0.1%(w/v). With increasing of ferulic acid concentration, the composite film of the DPPH radical scavenging activity was increased. Added 0.03% sodium citrate-0.1% ferulic acid the composite film had good properties.3. Nisin-CS/SPI cross-linked composite film was prepared with the addition of Nisin. The results showed that cross-linked composite film have antibacterial activities. The antioxidant property of cross-linked composite film was improved. With increasing of Nisin concentration, for staphylococcus aureus, escherichia coli and pseudomonas aeruginosa inhibition of capability was enhanced, the mechanical properties of the Nisin-CS/SPI cross-linked composite film decreased, the transparence declined, while water solubility and water vapor permeability increased.4. TP-CS/SPI cross-linked composite film with different amounts of TP was prepared. The results showed that antioxidant property, the mechanical properties and water vapor barrier properties of films were significantly increased with increasing of TP concentration, while the transparence declined.5.The CS/SPI cross-linked composite film, Nisin-CS/SPI cross-linked composite film and TP-CS/SPI cross-linked composite film were used for beef storage to investigate effectiveness of preserving. The results showed that as for beef wrapped with cross-linked composite film, the rises of pH value, TBA value and TVB-N value were delayed, the total number of microorganisms were inhibited effectively, the deterioration process was delayed during storage. Which TP-CS/SPI cross-linked composite film of inhibition of the oxidation of unsaturated fatty acids beef has played a good role, Nisin-CS/SPI cross-linked composite film effectively suppressed growth and reproduction of bacteria.