Study On The Effect Of Soluble Dietary Fiber On The Structural Properties Of Soybean Protein Emulsion Gels And New Product Development

In this study,soybean protein（SPI）and soluble dietary fiber（SDF）were taken as the research objects,and the effects of SPI content,Ca²⁺concentration,TG enzyme addition and other treatment conditions on the structural properties,rheological properties,water holding capacity（WHC）and other functional properties of emulsion gel in the process of enzyme salt ion bidirectional crosslinking were studied.The preparation process of protein emulsion gel was preliminarily determined.The effects of inulin,resistant dextrin and stachyose on the properties of gel were investigated,and stachyose was optimized to establish a composite emulsion gel system.Through in vitro simulated digestion and in vivo metabolic kinetics experiments,the effects of SPI-stachyose emulsion gel on the stability and bioavailability of vitamin D₃were investigated,and a high dietary fiber gel product was finally developed.The main conclusions are as follows:（1）The structure and properties of SPI emulsion gel prepared by different concentrations of SPI,Ca²⁺,and TG enzyme were studied;With the increase of Ca²⁺concentration,the viscoelastic properties and WHC of emulsion gel first increased and then decreased;With the increase of TG enzyme addition,the viscoelastic properties of gel first increased and then decreased.When the enzyme addition exceeded 30 U,it had little effect on the WHC of emulsion gel,while the viscoelastic properties of gel showed a downward trend.The optimal addition amounts for SPI,Ca²⁺,and TG enzymes are 10.49%,9.25 m M,and 31.58 U,respectively.（2）The formation and structural properties of emulsion gel prepared by adding SDF with different molecular weights were studied.In terms of texture properties,the addition of inulin had no significant effect on the texture of emulsion gel,while resistant dextrin and stachyose could significantly improve the hardness and elasticity of gel.In addition,the addition of inulin and resistant dextrin in gel did not change the viscoelastic properties of gel,while stachyose could significantly improve the viscoelasticity of gel.In terms of WHC,the addition of SDF could increase the proportion of gel bound water.In terms of gel structure,SDF and protein form covalent cross-linking,in which stachyose could improve the thermostability of gel,increase the content of protein secondary structure,and make the prepared gel structure more compact.（3）Vitamin D₃was selected as the active ingredient for embedding,and the digestion characteristics of different embedding systems were evaluated through in vitro digestion experiments and pharmacokinetic experiments.The results of in vitro digestion experiment and pharmacokinetics experiment showed that the emulsion gel with SPI-stachyose as the gel matrix had the highest bioavailability and embedding rate of vitamin D₃,which reduced the probability of vitamin D₃contacting with the external environment,thus increasing its content in intestinal fluid.In addition,the maximum blood concentration of vitamin D₃embedded in SPI-stachyose gel is the largest in vivo,and it takes the longest time to reach the maximum concentration,indicating that the stable three-dimensional network structure of SPI-stachyose gel is conducive to extending the retention time of vitamin D₃in vivo,and improving the bioavailability of vitamin D₃.（4）The effect of the addition of sucrose,sodium citrate and carrageenan on the sensory score of gel was investigated.Through single factor test and orthogonal test,the optimal formula of gel product was determined as follows:the addition of sucrose was 10%,the addition of sodium citrate was 1%,and the addition of carrageenan was 0.6%...