Properties of starch-based foam formed by compression/explosion processing

Single-use foam packaging is used by manufacturers to protect and preserve a wide array of food and industrial products. Starch is one possible altern ative material for making foam products. Starch-based foam was made using a compression/explosion process to study its properties and potential for si ngle-use packaging. A feedstock was first prepared which consisted of wheat (WS), corn (CS) or potato starch (PS) that was formed into aggregates (1-3 mm) and conditioned to moisture levels ranging from 8 to 20%. The conditio ned aggregates were loaded in an aluminum compression mold heated to 230 de greesC and compressed for 10 s with 3.5 MPa force. The force was instantane ously released resulting in an explosive release of steam as the starch fee dstock expanded and filled the mold. The moisture content of the feedstock influenced the density and compressive properties of the foam. Wheat, corn and potato starch feedstock with 17, 17 and 14% moisture content, respectiv ely, produced foam with some physical and mechanical properties similar to those of commercial food containers. The starch foam had the general shape of the mold and appeared similar to polystyrene, The microstructure of the foam revealed a cellular structure with mostly closed cells less than 1 mm in diameter. However, some regions of the foam had a microstructure similar to that of expanded polystyrene except that the cells were much small (< 0 .1 mm). (C) 2001 Published by Elsevier Science B.V.