ABSTRACT
Edible Œlms and coatings offer potential to extend the shelf life and improve the quality of virtually any food system. Edible Œlms and coatings can control moisture, oxygen, carbon dioxide, ¤avor, and aroma transfer between food components and the atmosphere surrounding the food. Several reviews are available on edible Œlm and coating systems (Gennadios et al., 1997; Krochta and De Mulder-Johnston, 1997; Arvanitoyannis and Gorris, 1999; Baldwin, 1999). The functional, sensory, nutritional, barrier, and mechanical properties of an edible coating can be altered by the addition of various chemicals in minor amounts (Krochta and De Mulder-Johnston, 1997; Debeaufort et al., 1998; Min and Krochta, 2005; Lin and Zhao, 2007). Films are usually regarded as stand alone, formed separate of any eventual intended use. Coatings involve formation of Œlm directly on the surface of the object they intend to protect or enhance in some manner (Krochta, 2002). One of the unique functions of both edible Œlms and coatings is the capability to incorporate functional ingredients into the Œlm or coating matrix to enhance its functionality. This may include
1. Improving basic Œlm or coating functionality, such as plasticizers for improved mechanical properties or emulsiŒers for increased stability and better adhesion
2. Enhancing food quality, stability, and safety by incorporating antioxidants, antimicrobials, nutraceuticals, ¤avors, and color agents
6.1 Introduction 157 6.2 Plasticizers 158
6.2.1 Plasticizers in protein Œlms and coatings 159 6.2.2 Plasticizers in polysaccharide Œlms and coatings 166
6.3 EmulsiŒers 167 6.4 Antimicrobial agents 170 6.5 Antioxidants and antibrowning agents 173 6.6 Nutrients, ¤avors, and colorants 175 6.7 Nanoparticles 176 References 177
Edible Œlms and coatings have received increasing interest because Œlms and coatings can carry a diversity of functional ingredients. Plasticizers, such as glycerol, acetylated monoglycerides, polyethylene glycol, and sucrose, are often used to modify the mechanical properties of the Œlm or coating. Incorporation of these additives may cause signiŒcant changes in the barrier properties of the Œlm. For example, the addition of hydrophilic plasticizers usually increases the water vapor permeability of the Œlm. Other types of Œlm additives often found in edible Œlm formulations are antimicrobial agents, vitamins, antioxidants, ¤avors, and pigments (Krochta et al., 1994). A greater emphasis on safety features associated with the addition of antibacterial agents is an active area of research in edible Œlm and coating technology (Cha and Chinnan, 2004). Application of nanoparticles to edible Œlms and coatings is another new research area. In this chapter, we will discuss intended and unintended effects of food additives on Œlm and coating properties.
