| Soybean meal,whose production is four times higher than that of the soybean oil,is a by-product of oil processing process.On account of its high content protein from 40%to 55%,soybean meal is often used as animal feed.Therefore,it is very significant that soybean meal’s protein is transformed into directly edible food products by some special methods.In this paper,firstly,extrusion technology was used to pretreat the soybean meal.And then the pretreated soybean meal was used for the extrusion texturization.By exploring the characteristics of the texturized products,the better extruded product will be applied to sausage production.Eventually,the availability and edibility of soybean meal will be improved.1.On the basis of single factor experiment,the central composite experimental BBD was used to determine the optimum parameters of the pretreatment of the soybean meal in the first extrusion process,which used Design-Expert software and mathematical models.Results indicated that the optimum technological parameters were:46%material moisture,201 r/min screw rotation speed,21.8 kg/h feeding speed,99.5℃ barrel temperature.Under the condition of these parameters,the water holding capacity could gain 2.12.Infrared spectroscopy and scanning electron microscopy suggested that its β-sheet increased while the globular structure became flake and porous structure in certain degree achieving the effect of pretreatment.2.The L16（45）orthogonal experiment and principal component analysis were used to optimize the extrusion texturization（secondary extrusion）in which the pretreated soybean meal,pig blood and starch were as the main materials.Results indicated that the optimal conditions were as follows:180℃ barrel temperature,13%pig blood,5%starch,320 r/min screw rotation speed,27 kg/h feeding speed.The final product（was called II for short）realized the perfect combination of plant and animal protein with rich nutrition and edibility.3.According to the above optimization of process parameters,the extruded product I was produced with the raw soybean meal.By comparing the properties of the Ⅰ and Ⅱ,the results suggested that the water absorption of II was significantly higher than that of I,while the volume density of II was smaller than that of I.Under different time and different cooking temperature conditions,the water holding capacity of II was significantly higher than that of I.The soluble dietary fiber of II was obviously higher than that of I.And the protein digestion rate in vitro of II was much higher than that of I.Electron microscope scanning images intuitively pointed out that the II had neat structure,organized order and close hierarchy,which was superior to I.Finally,the results confirmed the importance of the pretreatment of the soybean meal in the first extrusion process.4.Using the extruded product Ⅱ as the main raw material,L9（34）orthogonal experiment were conducted to get the optimum formula of the sausage.Results showed that the optimal ingredients of sausage were as follows:100%soybean protein II,35%wheat gluten,25%pumpkin powder,1.5%carrageenan,160%water.The color of the sausage was bright yellow,and the taste of the sausage was delicious.The sausage also had full-bodied bean fragrance,smooth surface and tightening organization.Comparing this sausage with commercial sausages,we found that in terms of appearance,this sausage needed to improve in some way.However,the sausage had the characteristics of convenience and ready-to-eat,which proved the feasibility of the extruded product added to the food. |
