| Pea protein has a low price and balanced nutrition.However,it is a high-quality plant protein resource.It is currently mainly used for the production of animal feed,and its advantages are not fully utilized.Pea protein is mixed with water,then sheared,heated,cooled and shaped to obtain meat analogues products by high-moisture extrusion technology.The meat analogues has similar to structure with animal muscle fibers.It can expand the application range of pea protein in the food industry.In this study,pea protein was used as the main raw material and processed by high-moisture extrusion technology.Texture analyzer,colorimeter,scanning electron microscope,rheometer,differential scanning calorimetry,fourier transform infrared spectrometer,fluorescence spectrophotometer,SDS-polyacrylamide gel electrophoresis and other technical means were used to analyze meat analogues.The main conclusions were as follows:(1)The effects of extrusion process parameters including extrusion temperature(100℃～180℃),moisture content(45%～65%)and screw speed(120 rpm～240 rpm)on pea protein-based meat analogues were studied.Specific mechanical energy,pressure and torque of the extrusion system parameters significantly decreased with the increase of the extrusion temperature and moisture content(P<0.05).Scanning electron microscopy images showed that increasing the extrusion process parameters promoted the formation of pea protein fiber structure,improved the order of fibers and reduced the number of stomata.Moreover,extrusion made structure of meat analogues more compact.The analysis of electrophoresis pattern showed that increasing the extrusion temperature and water content were beneficial to the aggregation of protein subunits and promoted the organization of protein to form fibers.Increasing the screw speed might cause the dissociation of aggregates and macromolecular proteins.Fourier transform infrared spectroscopy showed that the content of β-sheets significantly decreased,the content of random coils and β-turns significantly increased with the increasing effect of extrusion(P<0.05).Fluorescence spectroscopy showed that with the increase of extrusion temperature,moisture content decreased and screw rotation speed increased,and the protein absorption peaks occurred red shift and the fluorescence intensity became lower.The tertiary structure of the protein was destroyed.The increased of extrusion temperature and moisture content significantly improved the texture properties,degree of texturization,water holding capacity,oil holding capacity and sensory quality of meat analogues(P<0.05).The correlation analysis results showed that there was a significant or extremely significant relationship between extrusion system parameters and meat analogues quality properties,and the changes in system parameters can predict or regulate meat analogues quality.The response surface analysis method optimized the extrusion process,and obtained the optimal extrusion process parameters: extrusion temperature 140°C,moisture content 60%,and screw speed 150 rpm.(2)With the increased of gluten content from 0% to 40%,the apparent viscosity,elastic modulus and viscosity modulus of the mixed raw materials decreased.When the gluten content of more than 20%,the apparent viscosity of the raw materials did not change significantly.Specific mechanical energy,pressure and torque decreased significantly with the increased of the gluten content(P<0.05).When the gluten content of 40%,the specific mechanical energy,pressure and torque reached a minimum,respectively709.41 k J/kg,21.83 bar and 0.90 N.m.The microstructure of meat analogues changed after adding gluten.The fibrous shape transformed into the lamellar shape,and the pea protein fibers were distributed in the three-dimensional network structure of gluten.The gluten improved significantly the texture properties,degree of texturization,color and sensory quality of meat analogues(P<0.05).When the gluten content of 20%,the degree of texturization and sensory evaluation scores of meat analogues reached the maximum values of 1.53 and 82.04.(3)The analysis results of the pea protein-based meat analogues extrusion texturing process showed that from the raw material to the extrusion process,the disulfide bond content significantly increased,and the hydrophobicity of protein surface significantly decreased(P<0.05).The heat enthalpy and denaturation temperature of protein increased firstly and then decreased.The apparent viscosity of protein decreased firstly and then increased.The apparent viscosity in the melting zone was the lowest.In the die zone,the degree of protein aggregation increased,and the apparent viscosity increased.During the extrusion process,no new subunits appeared and no peptide bonds were formed.β-sheet decreased by4.22%,and β-turn increased by 3.82%(P<0.05).During the extrusion process,the protein absorption peak occurred red shift,the fluorescence intensity decreased.The protein tertiary structure was destroyed. |
