RELATIONSHIPS BETWEEN MICROSTRUCTURE AND MECHANICAL PROPERTIES OF CELLULAR CORNSTARCH EXTRUDATES RODERICK AGBISIT 1 , SAJID ALAVI 1,3 , ENZHI CHENG 1 , THOMAS HERALD 2 and ALLEN TRATER 1 * 1 Department of Grain Science and Industry 2 Institute of Food Science Kansas State University Manhattan KS 66506 Received for Publication March 3, 2006 Accepted for Publication January 12, 2007 ABSTRACT Relationships between mechanical properties and microstructure of brittle biopolymer foams were investigated using noninvasive imaging as a tool. Cornstarch was processed in a twin-screw extruder to produce brittle foams with varying microstructure. X-ray microtomography was used to measure microstructure features of the foams, including average cell diameter (2.07–6.32 mm), cell wall thickness (0.13–0.25 mm) and cell number density (18–146 cm -3 ). Mechanical properties, including compression modulus (2.2–7.8 MPa), crushing stress (42–240 kPa), number of spatial ruptures (2.6–3.6 mm -1 ), average crushing force (22–67 N) and crispness work (6.4–22 N·mm), were determined instrumentally. Compression modulus had a reasonably good fit (R 2 = 0.72) with the Gibson–Ashby model for brittle foams, while crushing stress did not fit as well (R 2 = 0.41). Cellular characteristics had moderate to high correlation (|r| = 0.48–0.81) with mechanical properties, and provided significant insight into the deformation mechanism of the foams. PRACTICAL APPLICATIONS Mechanical properties of extruded biopolymeric foams are largely deter- mined by their microstructure, but the relationships involved have not been properly understood. This study used mechanical testing in combination with 3 Corresponding author. TEL: 785-532-2403; FAX: 785-532-4017; EMAIL: salavi@ksu.edu * Present address: Frito Lay R&D, 7701 Legacy Drive, Plano, TX 75024 Journal of Texture Studies 38 (2007) 199–219. All Rights Reserved. © 2007, The Author(s) Journal compilation © 2007, Blackwell Publishing 199