Starch, corn fibers, magnesium stearate and PVA
were dry mixed using a Kitchen Aid mixer with a wire
whisk attachment. Batters not containing PVA or
having less than 50-weight parts of corn fibers had guar
gum (1% by weight of starch) added to prevent the
starch from settling. Enough water was added to the
mixture to reach the desired solids content and stirred at
room temperature for 10 min at medium speed (speed
setting 2). Foam trays were prepared using a lab modelbaking
machine (model LB TRO) supplied by Franz
Haas Machinery of America, (Richmond, VA). This
machine consists of two heated steel molds, the top of
which can be hydraulically lowered to meet the bottom
mold during baking. Dimensions of the mold were
217 mm long, 134 mm wide, 19 mm deep, and 3 mm
(plate separation). A 60-cm3 plastic syringe with an
enlarged opening was used to dispense the batter into
the open mold. Enough batter was drawn up into the
syringe and dispensed into the mold to just fill the
mold after foaming and form a complete tray. Baking
temperature was set at 200 C. Baking time was the
minimum required to avoid soft or bubbled trays and it
varied from about 120 to 180 s.