Effect of twin-screw extrusion parameters on quality attribute and comprehensive utilization of soybean meal in ruminants: Insight into protein structure, antioxidant activity and in vitro digestion

To investigate the effects of twin-screw extrusion parameters on glucose and soybean meal extrusion protein structure, antioxidant activity, and in vitro digestion, extruded soybean meal was prepared under different content of glucose (1–7%), feeding speed (40–120 rpm) and barrel temperature (120–160 °C). The increase in neutral detergent insoluble crude protein and a decrease in nitrogen solubility index were the primary drivers of the increase in rumen undegraded crude protein (RUP), which was comparable to the content of glucose. With regard to the variables of feeding speed and barrel temperature, the α-helix/β-sheets of the protein secondary structure exhibited a biphasic response, initially decreasing and subsequently increasing, which was similar to the observed change in RUP. For optimal utilization of the superior quality protein in soybean meal by ruminants, we recommend extrusion parameters of 2.5% glucose, a feeding speed of 80 rpm and a barrel temperature of 140 °C. [Display omitted] •Extrusion-assisted MR increased RUP (CP) through changed secondary structure.•The more D-glucose and slower feeding speed, the more significant enhancement of antioxidant of ESBM.•Excessive D-glucose added extrudate showed degraded by rumen microbes, leading to wastage.•Lower feeding speed increased the α-helix/β-sheets of the secondary structure while reducing RUP (CP).•Excessive barrel temperature led to excessive heat treatment of ESBM.