Preparation And Characterization Of Rapeseed Protein Based Nano-silver Antibacterial Composite Film

The waste of food plastic packaging has become a worldwide environmental problem.With arising awareness of environmental protection and health,edible film and degradable packaging tend to be a research hotspot.The content of this study are shown as follows:(1)In the development of edible protein based antibacterial composite films/food inner layer,we made a great improvement in the utilization of rapeseed protein and obtained the processing technical parameters for preparing the rapeseed protein based antibacterial composite film with high mechanical strength and desirable water vapor permeability,and gave advices for the rapeseed protein to be biodegradable and edible packing and use the film to preserve foods.(2)In improving the water vapor permeability and mechanical properties of the protein based film,we made a success in the preparation of nano-silver protein based composite antibacterial film with water vapor permeability and mechanical.(3)when comes to the effect of the antibacterial agents:nano-silver was synthesized and antibacterial activity effect for Escherichia coli and Lester bacilli was evaluated.The main results were shown as follows:First,the aim of the research is select the right plasticizer,through the characteration of the rheological properties of film-forming solution,the mechanical properties,water vapor permeability and the transparency of film,We concluded that the optimum conditions of film preparation is 4%(W/V)10%SRPI/30%SRPI,2%(W/V)glycerol/2%(W/V)sorbitol/1%(W/V)glycerol-1%(W/V)sorbitol as plasticizer and 1.5%(W/V)Twain 20 as an emulsifier.The results of rheological behavior of film-forming solution shows the RPI/10%SRPI film solution has low viscosity and can be used to prepare edible films.Succinylation as a method to improve protein solubility and has no significant(p>0.05)effect on the mechanical properties of the film.The film has high the mechanical properties and water vapor permeability prepared with succinylated rapeseed protein cooperated with 1%(W/V)glycerol-1%(W/V)sorbitol.Secondly,through the study of preparation of succinylated rapeseed protein and hydroxypropyl methyl cellulose(HPMC),we found that compared with the RPI film,the tensile strength of SRPI film increased by 18.7%,elongation at break increased by 38.7%,opacity increased by 121%,a-helix content increased and unordered content decreased in the secondary.When SRPI:HPMC=3:1,the water vapor permeability of the composite film increased by 24.1%,tensile strength increased by 101.3%.a-helix content was not obviously changed and the β-turn content was promoted,which is beneficial to the stability of the protein films.The microstructure of the composite membrane is compact and uniform,which indicates the there is a good compatibility between succinylated rapeseed protein and hydroxypropyl methyl cellulose.This study provides a theoretical basis for the development and utilization of rapeseed protein based composite films.Finally,though the study on antibacterial nano-silver succinylated rapeseed protein/hydroxypropyl methyl cellulose composite film.AgNPs was prepared by the reduction of silver nitrate with maltose in the system of sorbitol as a stabilizer.The size of 25 μM AgNPs was uniform,distributing at 80nm and 500nm and the the dispersion system was stable.The prepared AgNPs was added into the succinylated rapeseed protein/hydroxypropyl methyl cellulose composite film-forming solution to prepare the nano-silver composite antibacterial film.AgNPs has a great inhibition effect for both of two target bacteria,epecially for listeria.The lager concentration of nano-silver the more significant the antibacterial effect is.AgNPs has no significant effect on the film thickness and transparency.With the addition of AgNPs,the tensile strength of the composite film decreases and the elongation at break increases.The vapor permeability of nano-silver antibacterial composite film increases,but the effect is not obvious.Therefore,uccinylated rapeseed protein/hydroxypropyl methyl cellulose antibacterial composite film was prepared by selecting 25μM AgNPs.This experiment provides a new way for the synthesis and application of nano-silver.