In situ laminating process for baked starch-based foams

Single-use foam packaging made of extruded polystyrene (EPS) or coated paperboard (PB) is used for numerous food and beverage products. Considerable commercial interest is focused in developing new technologies for making single-use food containers that are partially or totally degradable in composting facilities. Wide interest has developed in a baking technology for making starch-based food containers with a hinged lid that appear similar to clamshell containers made of EPS. However, the starch-based food containers are brittle and moisture sensitive and must be coated after baking to provide an adequate moisture barrier. The present study describes an in situ method of baking and laminating the starch-based foams in a single step. The procedure involves a dough formulation consisting of starch, fiber and magnesium stearate that is placed in a mold-heated to 160 degreesC between two sheets of laminate. Sheets of laminate material tested included foil, tissue paper, weighing paper, polyvinyl alcohol film and polyvinyl chloride film. The laminated foams generally had a higher density, tensile strength, elongation to break and flexural strength than the non-laminated sample. All of the laminate materials decreased the water vapor permeance. Foam samples laminated with foil, polyvinyl alcohol (PVOH, processed at 130 degreesC) or polyvinyl chloride sheets had the lowest permeance values and had mechanical properties in the same range as those of commercial containers made of EPS or coated paperboard. Published by Elsevier Science B.V.