Studies On The Soy Protein/Polyvinyl Alcohol Biodegradable Film Modified By Transglutaminase

In this thesis, soybean protein and polyvinyl alcohol as the main film material,the tensile strength, elongation, transmittance and water absorption of the films werecompared to index for the evaluation of the films. In order to investigate the effect ofthe temperature of reaction, pH of reaction and mass fraction of TG on the propertiesof soy protein/PVA composite film. In ensuring the composite film has a certainmechanical properties and light transmittance,the H2O penetration rate, O2penetration rate,CO2penetration rate of the composite films were compared to indexfor the evaluation of the films. The structure of the soy protein/PVA composite filmand the composite film modified by TG was characterized.In this experiment, figspreservation with soybean protein/PVA composite film and the degradationproperties of the composite film were studied. Experimental results show that:1、The single-factor experiments results showed that, the reaction temperature,reaction pH, the mass fraction of TG had effect on tensile strength, elongation,transmittance and water absorption of soybean protein/PVA composite film.Theorthogonal experiment results showed that when the pH of reaction is5.0, temperatureof reaction is55℃, mass fraction of TG is0.20‰, soy protein/PVA composite filmhas the best performance. The impact of the three factors in descending order of thecomposite film is that reaction pH>the reaction temperature> the mass fraction of TG.2、The single-factor experiments results showed that, the reaction temperature,reaction pH, the mass fraction of TG had effect on the H2O penetration rate, O2penetration rate,CO2penetration rate of soybean protein/PVA composite film.When the pH of reaction is5.5, mass fraction of TG is0.20‰, temperature of reactionis53℃, soy protein/PVA composite film has the best performance. The orthogonalexperiment results showed that reaction pH has the biggest influence on the film,followed by the mass fraction of TG, followed by the reaction temperature. TGcrosslinking of the composite film reduced the moisture permeability andpermeability.3、The structure of the soy protein/PVA composite film and the composite filmmodified by TG was characterized through differential scanning calorimetry, fouriertransformation infrared spectrometer and scanning electron microscope. The resultshowed that both soy protein/PVA composite film and the composite film modified by TG had good hot workability, compatibility and thermoplastic, there was seriouslymicro phase separation phenomenonon the soy protein/PVA composite film.TGexpand the molecular structure of soy protein prompting the formation of a strongnetwork structure,thus improving the overall performance of the composite film.4、In preservation experiment, TG modified soybean protein/PVA compositefilm with figs matching degree higher than the commercially available polyethyleneplastic wrap and soy protein/PVA composite film. TG modified soybean protein/PVA composite film slowed down firmness rate of decline and consumption rate ofsoluble solids and VC.5、In degradation experiment, the two kind of films,weight loss rate had littledifference.The degrade effect of under outdoor natural conditions films generallybetter than in the indoor temperature and humidity conditions films.When thedegradation time arrived the ninth day, two kinds of films both in indoor temperatureand humidity conditions or outdoor natural conditions, weight loss rate all aboved60%.When the degradation of time reached the161th day, indoor temperature andhumidity conditions, soybean protein/PVA composite film and TG modified soybeanprotein/PVA composite film weight loss rate reached63.96%,64.11%,respectively;outdoors under natural conditions, weight loss rate reached65.96%and66.94%,respectively. TG can improve the mechanical properties of soy protein/PVAcomposite film, and did not affect the degradation of performance.