Effect Of Extrusion On The Characteristics Of Soybean Dregs Compound Powder And Its Application

Soybean dregs is a by-product of the processing of legumes,and a very nutritious food resource.Soybean dregs are rich in dietary fiber,which has an important role in promoting digestion and excretion of the human body.However,almost of these dietary fibers are insoluble dietary fibers,which are not easily absorbed by the human body.Therefore,they are often used in animal feed or directly discarded.In this paper,soybean dregs were used as the main raw material.Mixing with low-gluten flour,it was processed by extrusion technology to increase the content of soluble dietary fiber in soybean dregs and improve the quality of soybean dregs.Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),and scanning electron microscopy(SEM)were used to determine the properties of the soybean dregs compound powder after extrusion,and then the mechanism of the soybean dregs compound powder during the extrusion process was analyzed.And by analyzing the rheological properties of the soybean dregs compound powder,the application of the soybean dregs compound powder in cookies was adjusted to produce a high-quality healthy and leisure food--cookie,while providing a theoretical basis for the high-value utilization of bean powder.The soybean dregs were used as the main raw material,and the low-gluten flour was mixed to obtain the soybean dregs compound powder,which was extruded.The soluble dietary fiber content was taken as an index,and material moisture,extrusion temperature,and screw speed as single factors,the response surface method was used to optimize the extrusion puffing process.The optimal extrusion parameters were obtained when the material moisture content was 30 %,the extrusion temperature was 180 °C,and the screw speed was 160 r/min.The soluble dietary fiber content in the soybean dregs compound powder after extrusion and expansion was increased from 3.21 % to 15.47 %.Through FTIR and Particle Size analysis,the functional groups and particle size of the soybean dregs compound powder before and after extrusion were analyzed.The thermal stability was analyzed by DSC,the structure was characterized by SEM,and the water retention and oil retention of the soybean dregs compound powder before and after extrusion were measured.The water holding capacity of the soybean dregs compound powder was increased from 3.45 g/g to 4.86 g/g,and the oil holding property was increased from 2.27 g/g to 4.85 g/g.The number of functional groups of C-H bond,C-O bond,and-OH bond in the soybean dregs compound powder after extrusion increased,the intensity of the absorption peak increased,and the sugar absorption peak was obvious.After extrusion,the particle size of the soybean dregs compound powder reduced from 180.4 μm to 140.2 μm,and the endothermic peak temperature increased from 118.86 °C to 146.16 °C.It has a high degree of thermal stability.The structure changed from smooth and tight to rough and irregular,with obvious faults.After the soybean dregs compound powder is extruded,the structure becomes loose and porous,the chemical bonds were broken,and the macromolecular insoluble compounds are cracked to produce smaller molecular soluble compounds,which ultimately improves the water and oil retention.Soybean dregs were mixed with low-gluten flour to make batter,and its rheological properties were studied.The soybean dregs compound powder with different substitution amount of soybean dregs is used for extrusion treatment,and compared to cookie batter make from unextruded soybean dregs compound powder.When the amount of soybean dregs replacement in the unextruded soybean dregs compound powder is 30 %,the storage modulus and loss modulus of the cookie batter reach the maximum values of 4195.6 Pa and 2245.1 Pa,the low-frequency loss coefficient of cookie batter made from unextruded soybean dregs compound powder reaches a minimum of 0.535.When the amount of soybean dregs replacement is 25 %,the cookie batter made from unextruded soybean dregs compound powder reaches a minimum value of 0.777 at high angular frequency.When the amount of soybean dregs replacement in the soybean dregs compound powder after extrusion is 30 %,the storage modulus and loss modulus reach the maximum values of 6032.3 Pa and 1669.7 Pa,the cookie coefficient of the cookie batter made by soybean dregs compound powder after extrusion reaches a minimum value of 0.277 at low angular frequencies.When the amount of soybean dregs replacement is 35 %,the cookie coefficient of the cookie batter prepared by soybean dregs compound powder after extrusion reaches a minimum of 0.359 at high angular frequencies.In the measurement of creep and creep recovery,the cookie batter made from the soybean dregs compound powder after extrusion is lower than of unextruded soybean dregs compound powder.Finally,it was determined that the optimum amount of cookies was prepared when the amount of soybean dregs replacement in the unextruded soybean dregs compound powder was 25 %,and the optimum amount of cookies was prepared when the amount of soybean dregs replaced in the extruded soybean dregs compound powder was 35 %.The extruded soybean dregs compound powder was used as a raw material,a cookie was prepared.The sensory score of the cookie was as an indicator,butter whipping time,cookie baking temperature,and cookie baking time as the single factor,the best process parameters were obtained through orthogonal optimization experiments: butter whipping time of 8 min,and cookie baking temperature of 180 °C,cookie baking time 26 min.Under the optimal parameters,the sensory score of the cookie could reach 90,and the hardness was 1113 gf,which was similar to the commercially available cookie.The correlation between cookie quality and the soybean dregs compound powder index before and after extrusion was as follows: The sensory score was significantly positively correlated with extrusion and soluble dietary fiber content,and significantly negatively correlated with loss modulus and loss coefficient.Hardness is extremely significantly negatively correlated with extrusion treatments,significantly negatively correlated with soluble dietary fiber content,water holding capacity,and storage modulus,extremely significantly positively correlated with loss coefficient,and significantly positively correlated with shear strain.