Structure and Function of Starch-Based Edible Films and Coatings

Abstract

Edible films and coatings satisfy a variety of needs and meet specific product challenges for a large number of food applications. There is a general lack of agreement as to what constitutes a coating. A layer of seasoning on a snack or an oil spray applied to a cracker or a baked product, are examples of edible coatings. Further examples include soft, hard and chocolate panning in confectionery; application of carnauba wax to a gummy candy to preserve individual piece identity; application of icings or glazes to baked goods, use of caramel coatings for popcorn, and enrobing or dipping items in chocolate. Layers of barbeque sauce or fruit glaze on meats are coatings. Seasonings added to a chip, extruded corn collet or a rub applied to a chicken wing are often referred to as coatings. Tempura, battered and breaded fried appetizers are dependent upon coatings for their crunchy texture and eating quality. Egg wash layer added to yeast-leavened baked items for gloss is a protein-based aqueous edible coating. Liquid between air cells in foam could be described as a solute-stabilized edible film. The early Apollo astronauts ate foods coated with starch-based films to prevent the crumbs from becoming airborne and floating around the weightless environment of the cabin.

There are also examples of less traditional coatings and films, which are often freestanding or self-supporting. Edible packaging has been a topic of interest for many years, though few if any commercial examples exist. An invisible, edible coating would likely be more acceptable to consumers than petroleum-based plastic packaging. Edible coatings can make excessive packaging unnecessary, which is also perceived as a positive consumer benefit.