Effects of extrusion with CO2 injection on physical and antioxidant properties of cornmeal-based extrudates with carrot powder.

Carrot powder and cornmeal were extruded at ratios of 0:100, 10:90, and 20:80 with and without CO2 injection at die temperatures of 80, 100, and 120 °C. The effects of the composition of the extrudate, die temperature, and CO2 injection on physicochemical and antioxidant properties of extruded products were studied. The results showed that die temperature had a significant effect on expansion ratio (ER), specific length, piece density, color, water absorption index (WAI), and water solubility index (WSI) (p < 0.05). The injection of CO2 significantly affected the ER, WAI, WSI, lightness, redness, microstructure, total phenolic content, and the 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity of extrudates (p < 0.05). Increasing the proportion of carrot powder in extrudates resulted in better antioxidant properties and higher levels of crude ash, crude fat, crude protein, and redness; however, it resulted in lower WAI, lightness, and yellowness (p < 0.05). The study demonstrated that extrusion with CO2 injection and addition of carrot powder may improve the nutritional quality and structure-forming ability of extrudates.