Preparation Of Pea Protein Gel By Heat Treatment And Enzymatic Treatment And Its Properties

Pea is the third bean crop after soybean and peanut.It has high nutritional value,low price and low sensitization.At present,the focus of pea processing in China is mainly on the utilization of pea starch,and the use of pea protein as feed causes waste of resources.Gelation is an important functional property of proteins that contributes to the development of food diversity.Studies have shown that moderate modification of protein can improve gelation,and pea protein is not as functional as soy protein.Therefore,modification of pea protein contributes to the research and application of pea protein gel.In this study,pea was used as raw material.After degreasing,the pea protein was extracted by alkali-soluble acid precipitation process.The pea protein gel was prepared by heat treatment and enzyme treatment.The preparation conditions of pea protein gel were optimized,and the two pea protein gels were prepared.The physical and chemical properties and protein structure were analyzed.The main results are as follows:1.Preparation of pea protein gel by heat treatment and optimization of optimum process conditions:(1)The pea protein has good gelatinity and can be processed at a high temperature(80 ° C ? 100 ° C)to form a gel;(2)The optimal process parameters for the preparation of pea protein gel by heat treatment were determined by single factor and response surface test: protein concentration22%,p H 9.0,heat treatment temperature 95 ° C,heat treatment time 20 min.Under these conditions,the hardness of the pea protein gel was 0.05 ± 0.00 N,which was basically consistent with the theoretical value.2.Preparation of pea protein gel by flavor protease treatment and optimization of optimal process conditions:(1)Enzyme treatment of pea protein can form a gel under low temperature conditions(55?75 °C),and the hardness of the gel increases with the increase of temperature;while the heat-treated pea protein can not form a gel under the same conditions.;(2)The optimal process parameters for the preparation of pea protein gel by enzyme treatment were determined by single factor and orthogonal test: protein concentration 18%,enzyme amount 6 U/g,p H value 6.0,enzyme treatment temperature 70 °C,enzyme treatment time 50 min.The hardness of the pea protein gel prepared under the conditions was 1.32±0.01 N,which was basically consistent with the theoretical value.3.Analyze the physicochemical properties and protein structure of two pea protein gels:(1)The rheological properties of the pea protein gel were analyzed by rheometer.Theresults showed that the pea protein isolate without heat treatment and enzyme treatment was in a flowing state and could not form a gel.The pea protein isolate after heat treatment and enzyme treatment showed A clear gel characteristic curve was obtained;the creep and recovery characteristic curves of the pea protein gel showed that the two differently treated pea protein gels exhibited typical viscoelastic characteristics,of which the flavor protease-treated pea protein gel The elasticity is the best.(2)Solubility analysis results indicate that the formation of two differently treated pea protein gels is affected by hydrogen bonding,electrostatic interaction,and disulfide bonds,hydrophobic bonds,and non-covalent bonds.SDS-PAGE electrophoresis analysis of the pea protein gel samples showed that the composition of the heat-treated pea protein gel protein did not change significantly,while the concentration of the electrophoresis band of the pea protein gel treated with the flavor protease was significantly reduced.(3)Four-dimensional analysis of two differently treated pea gel proteins by Fourier transform infrared spectroscopy revealed that heat treatment had a certain effect on the random curl of pea protein,and had no significant effect on other structures;The treated pea protein did not undergo major changes in its traits.(4)Analysis of the tertiary structure of two differently treated pea protein gels revealed that the chemical force analysis of the pea protein gel samples showed that the hydrogen bond contribution of the pea protein gel prepared by heat treatment > the contribution of the ionic bond > The contribution of hydrophobic interaction,while the ionic bond is not the main chemical force of low temperature pea protein gel;the combination of surface hydrophobicity change and red shift of fluorescence spectrum indicates that after heat treatment and enzyme treatment,the original structure of the protein is destroyed.Hydrophobic groups are exposed,gels are formed by water-transport interaction;the content of exposed sulfhydryl groups and total sulfhydryl groups is increased after heat treatment,indicating that heat treatment exposes the sulfhydryl groups embedded in the protein molecules,and may cause the second part present in the molecules.Sulfur bond cleavage;the decrease in the total sulfhydryl group and exposed thiol content of the pea protein gel treated by the flavor protease may be due to the enzymatic treatment of the protein by the enzyme to combine the exposed thiol group with other groups to form a disulfide bond.