Effect Of Extrusion Conditions On Processing Properties Of Pea Flour And Its Main Components

Pea is a high-quality nutritious food with many values such as food,vegetables,feed and medicine.Food extrusion technology is also more recognized by the society in refining coarse grains and food processing.Extrusion of high temperature,high pressure,high shear mechanical operations will cause a series of changes in the main components of peas,such as starch gelatinization and the particle structure damage,protein denaturation and the molecular weight changes,resulting in changes in the processing characteristics of pea flour.Therefore,this paper used extrusion micro-extrusion technology,pea flour,pea starch and pea protein as raw materials,and extrusion temperature and material moisture as extrusion conditions to study the changes of processing and microscopic characteristics of pea starch and pea protein.On this basis,the changing conditions of the processing characteristics of pea flour were studied and the change mechanism were analyzed.The effects of adding pea flour on the characteristics of wheat dough and bread quality were further studied.The effects of extrusion temperature and material moisture on pea starch showed that the gelatinization viscosity of extruded pea starch decreased,the resistant starch content increased,the relative crystallinity decreased,and the crystal form changed from C type to A type.The degree of gelatinization and anti-digestibility of pea starch gradually increased with the increase of extrusion temperature and material moisture,and the degree of ordering and crystallinity of starch crystals also decreased significantly.The effects of extrusion temperature and material moisture on pea protein showed that the pea protein?-helix was completely disappeared,the?-sheet was relatively reduced,and the irregular curl content was increased.With the increase of extrusion temperature,the content of?-sheet decreased by 15.4%,random curl increased by nearly 15%,and?-turn decreased by only about 1.5%.Under different water conditions,the changes of the secondary structure of pea protein were different,indicating that there was a significant relationship between the conversion of secondary structure and the influence of material moisture and extrusion temperature.The electrophoretic bands of pea protein gradually became blurred,and the subunit distribution showed a tendency to change from high molecular mass to low molecular mass.The results of the study on the effect of extrusion temperature on the processing characteristics of pea flour showed that the particle diameter of extruded pea flour gradually increased with the increase of extrusion temperature,and the degree of spiral gradually increased.L*gradually decreased,a*and b*gradually increased,and the reaction affecting the color change of pea flour was intensified increased.WAI,WSI,SP,water solubility was better.T₀,T_p,T_c gradually increased,and the degree of gelatinization was higher;The viscosity values of?H and RVA were significantly reduced,and the?H value and RVA characteristic value were not detected when the extrusion temperature was 200?.Gel strength,hardness,elasticity,cohesiveness,adhesion,chewiness and recovery were first decreased and then increased.Therefore,when the extrusion temperature was 150?,the pea flour gel has the strongest heat resistance and shear resistance,high stability,gelatinization degree and ripening degree,and the mouthfeel was more delicate and smooth,and was easy to chew.This is important for the extrusion of pea flour as a convenient preparation product,which satisfies its edible quality such as easy dissolution,water swelling,good brewing and delicate taste,and is also beneficial to improve the basic texture of various compound foods.The effect of material moisture on the processing characteristics of pea flour showed that as the moisture content of the material increased,the surface of the extruded pea flour was rough,loose and porous,and the degree of gelation was higher.L*and b*were gradually reduced,and the total color difference?E was positively correlated with the moisture content of the material.WAI and SP gradually increased;T₀,T_p,T_c gradually increased,the gelatinization temperature gradually increased,the stability of pea flour became better,and?H gradually decreased.When the moisture content of the material was25%,the viscosity value of each characteristic of RVA was the smallest.Gel strength,hardness,elasticity,cohesiveness,adhesion,chewiness and recovery were gradually reduced.It showed that increasing the moisture content of the material can improve the gelatinization degree and water absorption of the extruded pea flour;make the mouthfeel more delicate and smooth,palatable and not sticky.The results of wheat dough characteristics and bread quality after adding pea flour and extruded pea flour showed that compared with the addition of pea flour,the T₂₁1 and A ₂₁1 of the dough after adding the extruded pea flour were reduced,and the degree of freedom of water was lowered.Viscosity and fermentation gas production were reduced,viscoelasticity was increased.The beany smell of peas was significantly reduced,color and odor were closer to whole wheat bread.The TPA characteristic value was lower than that of the whole wheat bread,the taste was soft and easy to chew,and the hardness change during storage was significantly reduced.Therefore,the addition of extruded pea flour can achieve the effect of both increasing nutritional quality without affecting the sensory properties of the bread.This study provides a certain theoretical basis and technical support for the application of extruded pea flour in pasta products.