DOI: 10.1094/CC-82-0305 |  VIEW ARTICLE

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.

A. H. Schmid (1), K. D. Dolan (2–4), and P. K. W. Ng (2). (1) Kraft Foods, 275 Cliff St., Battle Creek, MI 49014. (2) Food Science and Human Nutrition Department, Michigan State University, East Lansing, MI 48824. (3) Department of Agricultural Engineering, Michigan State University, East Lansing, MI 48824. (4) Corresponding author. Phone: 517-355-8474 ext 119. Fax: 517-353-8963. E-mail: <dolank@msu.edu> Cereal Chem. 82(3):305-313. Accepted October 14, 2004. Copyright 2005 AACC International, Inc.

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 (CO(2)) 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 CO(2) samples. Expansion ratio, bulk density, WAI, and %WSI were compared between control and treatment. CO(2) injection did not significantly increase expansion ratio. Bulk densities in the CO(2) extruded samples decreased when feed moisture decreased from 25 to 22%. The products using CO(2) had lower WAI values than products puffed without CO(2) at higher temperatures. The mean residence time was longer in CO(2) screw configurations than in conventional screw configurations. Thiamin losses were 10–16% in the control samples. With CO(2), 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 CO(2) injection is highly dependent on moisture content.