Edible films and coatings from biopolymers with specific properties have received increasing
attention since 1990s. Edible films are thin layers of edible material that are used to
encapsulate food and pharmaceutical products. They are formed on the surface of a food as a
protective or decorative coating, or placed between food components to separate them. They
can also be found as wrappings and pouches used to segregate sensitive ingredients in mixes,
or as a means of delivering just the right amount of a prepackaged ingredient.
Edible films have been applied to meat, poultry, fruits, vegetables, grains, confectionery
products, heterogeneous foods, any of which can be fresh, frozen, cured or processed.
Currently in the food and pharmaceutical industry, edible coatings and films are developed
from proteins, lipids, resins and polysaccharides. Each of these polymers possesses its own
combination of properties, addressing the needs of individual products. They can be used as a
monolayer or combined to form emulsions and bilayers.
The most important functionalities of an edible film or coating include control of mass
transfers, mechanical protection, and sensory appeal. Control of mass transfers involves
preventing foods from desiccation, regulating microenvironments of gases around foods, and
controlling migration of ingredients and additives in the food systems. Edible coatings on freash
fruit can provide an alternative to modified atmosphere storage by reducing quality changes
and quantity losses through modification and control of internal atmosphere of indivitual fruits.
Modification of internal atmospher by the use of edible coatings can increase disorders
associated with high carbon dioxide or low oxygen concentration, even though ingress of
oxygen may reduce food quality owing to oxidation of the aroma components in the food.
Also edible film with greater water vapour permeability is desirable for freash products ,
although an extremely high water vapor permeability is also not desirable as it can result in
excessive moisture loss of fruit during storage.
Adequate mechanical strength of an edible film is necessary to protect the integrity of
packaging throughout distribution. The sensory properties of an edible coating or film are a key
factor for acceptance of final products.
The development and characterization of edible films and coatings have increasly attracted the
attention of biochemists, biotechnologists, and physicists, among others, mainly to the large
variety of applications served by sing biopolymers. Particularly, the capability of edible films to
regulate moisture, lipid migration, and gas transport, can be used to improve food quality and
extend the life of foodstuff. In addition, edible films play an important role in the covering of
thermolabile compounds like vitamins, aroma, and flavours, and other food additives like
antioxidants, antimicrobial agents and colorants providing an efficient method to preserve their
characteristics during food processing.
One of the most important factors in the preparation of edibe films regards the choice of
ingredients. In last few years, the use of biomolecules, e.g. proteins, lipids, and polysaccharides,
has received special attention.