Effects Of Legume Protein On The Physicochemical Properties Of Buckwheat Starch And Its Application

Buckwheat,rich in nutrients,has a complete range of amino acids,which components include rutin and flavonoids with better health care effect.In recent years,buckwheat is widely used as healthy food ingredient,but its processing characteristics and taste are not desirable.In order to improve the processing characteristics of buckwheat flour,this study mainly investigated the effects of mung bean protein,adzuki bean protein,black bean protein and soybean protein on the gelatinization,rheological,thermal,texture and microstructure of buckwheat starch.The interaction mechanism between four legume proteins and buckwheat starch was investigated.Adding four kinds of legume flour to buckwheat flour can significantly improve the brittleness of buckwheat flour?p<0.05?.This study provided reference for the upcoming research of legume protein and buckwheat starch interaction and the development of buckwheat products.The main results are as follows:1.Study on the effect of four legume proteins on the physical and chemical properties of buckwheat starch.The effects of four legume proteins on the gelatinization,rheological properties,thermal properties,texture properties and microstructure of buckwheat starch were studied by RVA,rheometer,DSC and texture analyzer.The RVA test results showed that the peak viscosity decreased significantly?p< 0.05?when the ratio of buckwheat starch to mung bean protein,adzuki bean protein,black bean protein and soybean protein was 8:2,the peak viscosity decreased from 4481 MPa?s to 1738 MPa?s,1597 MPa?s,1954 MPa?s and 1421 MPa?s.The regeneration value decreased from 1988 MPa?s to 965 MPa?s,1030 MPa?s,1318 MPa?s and 1522 MPa?s,respectively.The rheological test results showed thatthe apparent viscosity of the mixed system decreased,the K value decreased with the increase of the proportion of four legume proteins,the system was pseudoplastic fluid,the storage modulus G' and loss modulus G" decreased significantly,and the tangent value of loss angle increased.The results of DSC showed that the initial gelatinization temperature?T_O?and peak temperature?T_P?of the system increased after adding four legume proteins.When the ratio of buckwheat starch to mung bean protein,adzuki bean protein,black bean protein and soybean protein was 8:2,the enthalpy value?? H?decreased from 6.60 J/g to 5.54 J/g,5.70 J/g,5.56 J/g and 5.57 J/g,respectively.The results of texture test showed that the hardness and chewiness of the mixed gel decreased significantly?p<0.05?.Scanning electron microscopy?SEM?showed that compared with buckwheat starch gel,the pore size of the mixed gel increased,the pore wall became thinner,and the gel network structure was loose.2.Study on the effect of four legumes on the properties of buckwheat dough.The changes of water holding capacity,texture properties and tensile properties of buckwheat dough were studied by NMR and texture analyzer.The results of NMR analysis show that the main form of water in dough is weak coalescence water.Compared with buckwheat dough without legumesflour,the peak area A₂₁of coalescence water reaches 407.733 when the amount of mung bean flour is 23%,and the peak area A₂₁of coalescence water reaches 124.7482 when the amount of adzuki bean flour is 25%.When the content of black bean flour was more than 11% and that of soybean flour was more than 12%,the free water appeared in the dough,and the water holding capacity was declined.The results of texture test showed that the hardness and chewiness of the dough decreased significantly with the increase of soybean flour?p< 0.05?,and the viscosity of buckwheat dough without soybean flour was 18.28,compared with 236.91,239.83,374.34 and 389.07 when mung bean flour,adzuki bean flour,black bean flour and soybean flour were the maximum addition.The results of tensile test showed that with the increase of legumes flour,the tensile force of the dough decreased,the tensile displacement of the dough increased significantly?p< 0.05?,the tensile displacement of the dough of adzuki bean flour did not change significantly?p< 0.05?,and the tensile displacement of the dough of black bean flour and soybean flour increased first and then decreased.With the addition of soybean flour,the texture of the dough is soft,but the processing performance of the dough is reduced.Therefore,it is determined that the addition amount of mung bean flour,adzuki bean flour,black bean flour and soybean flour are 23%,25%,11% and 12% respectively.3.Study on the effect of four legumes on the brittleness of buckwheat.The shear hardness and brittleness of each kind of legumes were measured by texture analyzer,and the effects of different legumes on the properties of the surface were compared.The results of texture analysis showed that the difference of shear hardness and brittleness between different legumes flour was significant,and the hardness of the surface decreased and the brittlenesss of the surface increased after adding four legumes flour.Among them,the influence on the shear hardness of the flat surface is adzuki bean flour,mung bean flour,black bean flour and soybean flour.The effect on the brittleness of the noodle was from adzuki bean flour,mung bean flour,soybean flour and black bean flour.It shows that the addition of adzuki bean flour has the most significant effect on the quality of instant noodles.