Effect of high‐pressure CO₂ injection on the physicochemical properties and lipoxygenase activity of extruded rice bran

Abstract

Background and Objectives Rice bran is rich in nutrients but not very stable and available, so extrusion of it broadens its utilization value. The objective was to investigate the effects of extrusion parameter variables on the physicochemical properties and lipoxygenase activity of extruded rice bran. The extrusion parameter variables were set as extrusion temperature (80, 90, 110, 140°C); CO2 injection, and no CO2 injection; screw speed (200, 300 rpm). Findings CO2 injection significantly affected the expansion characteristics and lipoxygenase activity of extruded rice bran. It better inhibits lipoxygenase activity and at a fixed screw speed of 200 rpm, the bulk density of extruded rice bran with CO2 injection was higher than that of conventional extrusion. After extrusion, the soluble dietary fiber content was significantly increased in the extruded samples compared with the raw material. In contrast, the content of dietary fiber was not significantly affected by CO2 injection. Conclusions Compared with the conventional extrusion method, the CO2‐injected extrusion has significant effects on the expansion characteristics and nutritional composition. Extrusion with CO2 injection can reduce lipoxygenase activity more effectively. Significance and Novelty The results prove that CO2 extrusion can inhibit the lipoxygenase activity, and change the physicochemical properties of rice bran compared with conventional extrusion. It provides a basis for the application of CO2 as a medium in extruded rice bran food and a new process for processing rice bran by‐products.