Composite coatings or multilayer coatings on paper packaging
materials, applied either in the form of an emulsion or in successive
layers (multilayer coating), have been prepared to combine
the good structural and gas-barrier properties of hydrocolloid coatings
with the good moisture-barrier characteristics of lipids. In a
previous study, Khwaldia (2010) processed a water vapor-barrier
packaging material with paper, caseinate, and paraffin wax. She
found that the greatest reduction in paper water vapor permeability
(WVP) is achieved by addition of a wax layer to the paper already
coated with caseinate, due to the high resistance to moisture transfer
of the paraffin wax. Unfortunately, the content of paraffin wax
of packaging materials makes it difficult to separate, recycle or
compost them after use.