Chemical changes in soybean and corn processed by extrusion

The effects of temperatures of extrusion process on characteristics of nitrogen and carbohydrates fractions, ether extract, in vitro protein digestibility and trypsin inhibitor factor of soybean and corn. The experiment was conducted in a completely randomized design, with three replicates in a 5 x 4 factorial arrangement, with five combinations of soybean and corn (100% soybean, 75 soybean and 25 corn, 50 soybean and 50 corn, and 25 soybean and 75 corn, 100% corn, % DM) and four temperatures of extrusion (without extrusion and extrusion at 80, 100 or 120 degrees C). The process of extrusion promoted increase in the lipid fraction and reduction in levels of neutral detergent fiber (NDF) and acid detergent fiber (ADF), which changed according to the proportion of soybean and corn and the temperature of processing, consequently, the levels of neutral detergent insoluble protein (NDIP) and acid detergent insoluble protein (ADIP) reduced. The same trend was observed in levels of lignin, which were lower in combinations with up to 50% of soybean, processed at 120 degrees C. The extrusion, regardless of temperature, promoted increasing of A fraction of carbohydrates. The B2 and C fractions decreased with the increase of soybean in the combinations. Extrusion reduced the A, B1 and C nitrogen fractions in combinations containing soybean. Extrusion increase B2 fraction except for 100% corn. Lesser alterations were observed in the B3 fraction. Extrusion did not alter in vitro protein digestibility of soybean and corn, however, reduces the amount of trypsin inhibitor factor of when the combinations of these grains are extruded at 120 degrees C.