Study On The Change Of Soybean Meal In Extrusion Processing And Its Effect On Ruminant Digestibility

The degradation of protein and the metabolism of ammonia in ruminant rumen feed have always been remarkable problems.The mechanical force generated in the extrusion process will denature the protein by destroying the molecular structure,and Maillard reaction will occur in the process,which will reduce the ammonia production rate in rumen and improve the utilization rate of protein.Extrusion processing is instantaneous and efficient,energy consumption is reduced,and production cost is saved.It is a new technology for preparing rumen feed for ruminants with high efficiency.In this paper,the preparation method of ruminant rumen protein powder was studied by extrusion technology.The research contents are as follows: Firstly,the influence of the change of extruder operating parameters(barrel temperature,material water content,screw speed)on system parameters(torque,die pressure,unit mechanical energy,etc.)in the extrusion process was studied by system analysis method;Secondly,by measuring the properties of the extrudate(browning degree,color difference,solubility,surface hydrophobicity,digestibility,etc.),the optimal parameters were obtained.The research results show that:(1)The change of operating parameters has a great influence on extruder system parameters.The die pressure decreases with the increase of barrel temperature and water content,and the die pressure reaches the maximum at 110 ℃ and 15% water content.With the increase of screw speed,the die pressure tends to decrease.With the increase of water content,the torque decreases.When barrel temperature and screw speed increase,torque generally shows a decreasing trend.When the water content is15%,the temperature is 110 ℃ and the screw speed is 275 rpm,the torque is the maximum.With the increase of barrel temperature and material moisture content,SME decreases;With the increase of screw speed,SME will also increase.When the water content is 15% water,the temperature is 110℃ and the screw speed is 450 rpm,the SME is the largest.When adding glucose with different contents,the die pressure,torque and SME will decrease with increasing glucose addition,and the die pressure,torque and SME will be the highest when glucose content is 1%.The experimental results show that there is correlation and mutual influence among extruder system parameters,which can be used to estimate extruder system parameters and control extrudate quality better.(2)The degree of Maillard reaction is inversely proportional to the moisture content of materials;Is proportional to the temperature;It is not affected by the speed of screw.The higher the p H value,the greater the Maillard reaction degree.The Maillard reaction degree will be different when adding different amounts of glucose.The Maillard reaction degree is the strongest under the conditions of 15% water and150℃,and the Maillard reaction degree is the highest when phosphate buffer solution with p H=6.5 is added.There is a correlation between absorbance and color of samples,and absorbance is negatively correlated with L*,positively correlated with a*,positively correlated with △ E*,and has no significant effect on b*,so Maillard reaction degree can be determined according to L*,a* and △E*.(3)Protein denaturation by extrusion leads to changes in solubility and surface hydrophobicity.The digestibility of crude protein and dry matter in rumen of extruded feed is different under different conditions.After 24 h culture,the degradation rate of the sample feed and the Maillard reaction degree of the sample showed an obvious trend,and a regression equation could be obtained,which could be applied to actual production.