Study On The Preparation And Properties Of Active Composite Films Based On Soybean Polysaccharide And Essential Oils

Food packaging plays an important role in protecting food from the external environment and prolonging the shelf life of food.The problem of environmental pollution caused by traditional petroleum based synthetic plastic food packaging is becoming more and more serious.With people’s yearning for a better life and the improvement of ecological environmental protection awareness,people begin to pursue biodegradable and environmentally friendly biomass based packaging.soluble soybean polysaccharide(SSPS)is a kind of renewable and edible dietary fiber produced by the production of soybean protein isolate,soybean milk and bean curd.It has excellent film forming performance,oxidation resistance and stability.Essential oils(EOs)are natural active substances extracted from plants.They have excellent antibacterial and antioxidant properties and have been recognized as safe food additives by FDA.In order to broaden the application field of SSPS and realize the low value transformation of soybean by-products,this study took SSPS as the matrix and introduced essential oils as the active substance to develop the active food packaging materials.On this basis,carboxymethyl chitosan,Pullulan polysaccharide and nano zinc oxide were added to improve their physicochemical properties,and a series of active composite films based on SSPS/EOs were developed,and their physicochemical properties,antibacterial activity and oxidation resistance were analyzed.The main research contents are as follows:Firstly,tea tree essential oil(TTEO)and nano zinc oxide(Zn O)were introduced into SSPS matrix to prepare an active packaging film with dual antibacterial mechanism.The results showed that the introduction of TTEO increased the antioxidant activity of SSPS film from 46.79% to 67.71%.The addition of TTEO or Zn O can improve the UV barrier and antibacterial properties of the film.However,when TTEO and Zn O both are added,SSPS/TTEO/Zn O composite film shows the best UV barrier,water vapor barrier ability and antibacterial activity.At the same time,the antibacterial test results showed that the antibacterial effect of SSPS composite films was in the order of SSPS/TTEO/Zn O > SSPS/Zn O > SSPS/TTEO,indicating that TTEO and Zn O have synergistic antibacterial effect.These studies prove that SSPS/TTEO/Zn O composite film can be used as an ideal packaging matrix for food preservation.Secondly,in order to improve the physical properties of SSPS/lavender essential oil(LEO)system,carboxymethyl chitosan(CMCS)was introduced to prepare SSPS/CMCS/LEO antibacterial coating material.The effects of CMCS and LEO on the physicochemical properties of SSPS composite film were studied,and its application in banana preservation was preliminarily explored.The study on optical properties and morphology showed that SSPS and CMCS have good compatibility.The introduction of CMCS significantly improved the mechanical properties,barrier properties,thermal stability and other macro properties of SSPS film.When the content of LEO was 1%,the inhibition rate of SSPS/CMCS/LEO coating film against Staphylococcus aureus and Escherichia coli was 90.1% and 82.8%,respectively.Compared with SSPS/CMCS coating,SSPS/CMCS/LEO emulsion coating can significantly prolong the shelf life of bananas stored at room temperature.Finally,SSPS/PLN composite film was prepared with SSPS and Pullulan polysaccharide(PLN)as raw materials.Different contents of LEO and clove essential oil(CEO)were added into SSPS/PLN film matrix,and the effects of concentration and type of essential oil on the properties of SSPS/PLN composite film were studied.The results showed that with the increase of LEO concentration,the tensile strength of SSPS/PLN film decreases gradually,the elongation at break,the UV barrier ability and the color difference increases,the water vapor transmittance and water solubility decrease.The addition of LEO and CEO reduces the thermal stability of the film.SSPS/PLN composite film containing CEO exhibited better antioxidant and antibacterial properties when the two essential oils were at the same concentration.