DisplayTitle

Effect of Extruding Wheat Flour at Lower Temperatures on Physical Attributes of Extrudates and on Thiamin Loss When Using Carbon Dioxide Gas as a Puffing Agent

¹Kraft Foods, 275 Cliff St., Battle Creek, MI 49014. ²Food Science and Human Nutrition Department, Michigan State University, East Lansing, MI 48824. ³Department of Agricultural Engineering, Michigan State University, East Lansing, MI 48824. ⁴Corresponding author. Phone: 517-355-8474 ext 119. Fax: 517-353-8963. E-mail: dolank@msu.edu

Wheat flour with 0.3% (w/w) thiamin was extruded on a twin-screw laboratory-scale extruder (19-mm barrel) at lower temperatures and expanded using carbon dioxide (CO₂) gas at 150 psi. Extrusion conditions were die temperature of 80°C and screw speed range of 300–400 rpm. Control samples were extruded at a die temperature of 150°C and screw speed range of 200–300 rpm. Dough moisture content was 22% in control samples and 22 and 25% in CO₂ samples. Expansion ratio, bulk density, WAI, and %WSI were compared between control and treatment. CO₂ injection did not significantly increase expansion ratio. Bulk densities in the CO₂ extruded samples decreased when feed moisture decreased from 25 to 22%. The products using CO₂ had lower WAI values than products puffed without CO₂ at higher temperatures. The mean residence time was longer in CO₂ screw configurations than in conventional screw configurations. Thiamin losses were 10–16% in the control samples. With CO₂, thiamin losses were 3–11% at 22% feed moisture, compared with losses of 24–34% at 25% moisture. Unlike typical high-temperature extrusion, thiamin loss in the low-temperature samples decreased with increasing screw speed. Results indicate that thiamin loss at lower extrusion temperatures with CO₂ injection is highly dependent on moisture content.