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

Abstract

Carrot powder and cornmeal were extruded at ratios of 0:100, 10:90, and 20:80 with and without CO injection at die temperatures of 80, 100, and 120 °C. The effects of the composition of the extrudate, die temperature, and CO 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) ( < 0.05). The injection of CO significantly affected the ER, WAI, WSI, lightness, redness, microstructure, total phenolic content, and the 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity of extrudates ( < 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 ( < 0.05). The study demonstrated that extrusion with CO injection and addition of carrot powder may improve the nutritional quality and structure-forming ability of extrudates.

Effects of different blowing agents on physical properties of extruded puffed snacks made from yellow pea and red lentil flours

“…A higher yellow pea extrudate density with CO 2 injection compared to N 2 injection and conventional extrusion may be due to the differences in the solubility of CO 2 as compared to N 2 (approximately 1.5–2 orders of magnitude difference in their solubility in water at ambient temperature and pressure [Gevantman, ]). A higher extrudate density with CO 2 injection was also seen in barley flour supplemented and vitamin fortified corn extrudates (Bilgi Boyaci et al, ; Masatcioglu, Gokmen, et al, ; Masatcioglu, Yalcin, et al, ) at a relatively low temperature (i.e., 80 °C) and in carrot powder supplemented cornmeal extrudates (Samard et al, ) at a temperature similar (i.e., 130 °C) to what is used in this study. A decrease in extrudate density and an increase in expansion index, although not statistically significant, in the presence of N 2 gas injection were also reported for puffed yellow pea snacks at the same temperature as in this study (Koksel & Masatcioglu, ).…”

“…It has been previously reported that hardness and crispiness have an inverse relationship (Oliveira et al, ). This trend is heavily dependent on die temperature, screw speed, and moisture content (Ding et al, ; Lohani & Muthukumarappan, ; Samard et al, ). The selected temperature, screw speed, and moisture content in this study did not allow this trend to be observable when comparing the conventional and physical blowing agent‐assisted extrudates.…”

“…The most common physical blowing agent in food extrusion is CO 2 in its supercritical or subcritical form. The use of CO 2 during extrusion to enhance texture and structure of foods has been investigated in a variety of products such as sorghum flour, cornmeal, waxy rice, and wheat (Lohani & Muthukumarappan, ; Samard et al, ; Shen, Gil, & Ryu, ; Singkhornart et al, ) but not for pulse products. Moreover, the use of physical blowing agents other than CO 2 is quite rare in food extrusion, especially for higher protein and/or fiber containing raw materials such as pulses, with only one recent study focusing on N 2 gas as a physical blowing agent during extrusion cooking of yellow pea flour (Koksel & Masatcioglu, ).…”

“…However, several studies have reported that desirable characteristics such as overall expansion are reduced when high concentrations of proteins and/or fibers are present (Philipp, Emin, Buckow, Silcock, & Oey, 2018;Philipp, Oey, Silcock, Beck, & Buckow, 2017;Ryu & Ng, 2001). The use of physical blowing agents (such as gases) can remedy such challenges, since they provide nucleation sites for bubble formation and growth, in addition to steam expansion observed during high temperature (>100 C) extrusion (Koksel & Masatcioglu, 2018;Samard, Singkhornart, & Ryu, 2017;Singkhornart et al, 2014).…”

“…The most common physical blowing agent in food extrusion is CO 2 in its supercritical or subcritical form. The use of CO 2 during extrusion to enhance texture and structure of foods has been investigated in a variety of products such as sorghum flour, cornmeal, waxy rice, and wheat (Lohani & Muthukumarappan, 2017;Samard et al, 2017;Shen, Gil, & Ryu, 2013;Singkhornart et al, 2014) but not for pulse products.…”