Edible Fims and Coatings from Plant Origin Proteins

Abstract

This chapter discusses the film formation ability and associated functional properties of a number of plant proteins, namely those extractable from corn, soybean, wheat, cottonseed, and other crops. Soy protein films are typically prepared from Soy protein isolate (SPI) by drying thin layers of cast film forming solutions. The drying temperature and RH that determine the drying rate of cast solutions can also affect the film structure and properties. The high oxygen-barrier capability of SPI films could be utilized in the manufacture of multilayer packaging, where protein films would function as the oxygen barrier providing layer. SPI coating on precooked meat products could control lipid oxidation and limit surface moisture loss. Further, wheat gluten (WG) films have been produced by collecting the surface skin formed during the heating of WG solutions to temperatures near boiling. Application of WG-based materials can be envisioned for the coating of seeds, pills, and foodstuffs, and for making cosmetic masks, polishes, or drug capsules. There are other plant proteins of limited availability that may be of interest, due to a unique property they provide to films or an advantage with regard to film formation. Limited availability may be because of relatively low production of the protein source or limitations in recovering the protein as a coproduct from a process. The nature, recovery, film formation, and film properties of protein obtained from peanut, rice, pea, pistachio, and grain sorghum are also described in this discussion.