Study On Film Forming Characteristics Of Tremella Polysaccharide

In this paper,The polysaccharides from Tremella fuciformis was extracted by pressurized hot water extraction.We optimize the extraction technology parameters,purify tremella polysaccharide(TP),analyze monosaccharide composition,preliminary structure and its antioxidant activity,at the same time,the rheological properties of TP solution and film forming characteristics were analyzed,and the relationship between the rheological and film-forming was studied.Subsequently,the preparation and research of the polysaccharide composite film of TP and sodium alginate(SA)were carried out at different mixing ratios.It provides some scientific basis for the further processing of tremella and the application of edible film.The results are as follows: 1.Optimization of extraction process of TP to separate and purify monosaccharide composition and structure analysisThe Polysaccharide(TP)was extracted from tremella fuciformis by pressurized hot water method.The polysaccharides were isolated and purified,the composition and structure of monosaccharides were identified and analyzed.The optimum extraction technology was determined by orthogonal experiment.The optimum parameters were as follows: liquid ratio 1:7512(g/mL),extraction temperature 120 ?,extraction pressure 1.0 MPa,extraction time 40 min.Under the condition of the extraction yield of polysaccharide was(70.25 ± 0.08)%.The homogenous tremella polysaccharide(TP-1-1)was isolated and purified by DEAE-52 cellulose column and Sephadex G-100 column chromatography respectively.The results of UPLC showed that TP-1-1 was composed of Man,Gal,Glc and Ara monosaccharides with different molar ratios.The molar ratios were 7.36:18.10:8.39:4.93.Infrared spectrum indicated that TP-1-1 had the characteristic structure of polysaccharide.2.Determination of antioxidant activity of TPBoth TP and homogenized polysaccharide TP-1-1 obtained by separation and purification had a certain scavenging effect on hydroxyl radical and superoxide anion radical,and showed a good scavenging ability in a certain concentration range,and the scavenging ability was positively correlated with the mass concentration of the sample.3.Rheological properties of tremella polysaccharide solution(TPS).The rheological properties show that TPS showed a shear-thinning(pseudoplastic)behaviour,and its pseudoplasticity was more obvious at a concentration of 2.00%.The Power-law model was used to evaluate the viscosity curves of TP,and its viscosity and consistency indices both increased as the concentration increased,whereas both indices decreased as the concentration decreased.The viscosity of TPS changed as the pH changed: TPS had a higher viscosity at pH=6 and a lower apparent viscosity at pH=2 and pH=10.There was a negative correlation between the viscosity and temperature of the TPS system.In dynamic viscoelasticity,TPS behaved as a weak gel at a concentration of 2.00% at high frequencies and possibly as a true gel at higher concentrations.The rheological properties show that TP can be used as an edible film material.4.Properties and structure analysis of edible film of TPEdible film of TP was prepared,And the mechanical,optical and water soluble properties of edible film of TP with different concentration were studied.The results showed that the edible membrane prepared by 1.50% TPS had the best mechanical properties(tensile strength(TS): 15.05 MPa,elongation at break(EAB): 23.35 %),good light transmittance,water solubility and water vapor permeability.The results of FTIR and SEM showed that there were strong hydrogen bond interactions among TP? glycerol and water molecules,the interaction was strongest and the compatibility was best when the concentration of TP was 1.50% and 1.75%.5.Properties and structure analysis of tremella polysaccharide composite filmThe polysaccharides of tremella fuciformis and sodium alginate were blended according to different proportions,and the mass ratio was(1:3,2:2,3:3).The rheological properties of the blend solution showed that sodium alginate significantly improved the viscosity of the film solution,but the phenomenon of shear thinning still existed.The mechanical properties and light transmittance of the composite film were improved.The optimal ratio of tremella polysaccharide/sodium alginate(TP-SA)in was 2:2,the TS of the film was 46.92 MPa(two times higher than that of TP),the EAB was 13.53%,and the water solubility,light transmittance and water vapor permeability were also improved.FTIR showed that there was a strong hydrogen bond between TP and SA molecules,which promoted the formation of a dense network structure between them,and the polysaccharide molecules and sodium alginate in the polysaccharide composite film had a good compatibility.SEM showed that the composite membrane of tremella polysaccharide and sodium alginate had regular and dense cross sections without obvious phase separation,which indicated that the composite film had good compatibility among various components.When the complex ratio was TP:SA= 2:2,the surface morphology and structure of the membrane reached the best.