Publication no. C-1997-0821-07R |  VIEW ARTICLE

Influence of Particle Size on the Twin-Screw Extrusion of Corn Meal (1).

B. W. Garber (2), F. Hsieh (2,3), and H. E. Huff (2). (1) Contribution of the Missouri Agricultural Experiment Station, Journal Ser. 12,603. (2) Departments of Biological and Agricultural Engineering and Food Science and Human Nutrition, University of Missouri, Columbia, MO 65211. (3) Corresponding author. E-mail: <fu-hung_hsieh@muccmail.missouri.edu> Cereal Chem. 74(5):656-661. Accepted June 11, 1997. Copyright 1997 by the American Association of Cereal Chemists, Inc.

Effects of particle size (50-1,622 µm), screw speed (200-400 rpm), and feed moisture content (19-22%) on twin-screw extrusion of corn meal were investigated using a full-factorial design. Torque, specific mechanical energy, and product temperature generally showed no change within the commonly used particle-size range (100-1,000 µm), but each value dropped significantly as the particle size increased >1,000 µm. Die pressure was influenced by the three-way interaction of particle size, screw speed, and feed moisture content. The highest moisture level (22%), largest particle size (1,622 µm), and two lowest screw speeds (200 and 300 rpm) were the only conditions where the starch was <97.5% of transformation (gelatinization). Consequently, these two conditions also showed the least expansion and hardest product.