Alternatives to synthetic plastics used in ovenable trays for frozen f
oods are of interest because of environmental and food safety concerns
. A new technique for making a compression molded starch-based plastic
is described that uses starch foams rather than starch powders as a f
eedstock. Starch foams were compressed between polished, unheated plat
ens into plastic sheets from which tensile bars were cut. The starch p
lastic had the highest tensile strength when compressed greater than 6
9 MPa. Starch powders that were compressed under identical conditions
did not form a cohesive starch plastic. Initially, the tensile strengt
h of the starch plastic derived from starch foams was comparable to th
at of polypropylene. However, tensile and flexural strength decreased
with time for starch plastics stored at room temperature or -20 degree
s C. The functional properties of samples that were baked in contact w
ith three different food types (low moisture, high moisture, oily) wer
e studied. The tensile and flexural strength of polypropylene samples
were not affected by baking treatments. However, the starch plastic sa
mples lost both tensile and flexural strength and formed numerous blis
ters in some treatments. Maltose was blended into the starch plastic i
n efforts to reduce the hygroscopicity of the starch and decrease blis
ter formation. While maltose significantly reduced the hygroscopicity
of the starch plastic, it did not prevent blister formation. (C) 1997
Elsevier Science B.V.