Self Supporting Edible Films

Self Supporting Edible Films

Self-supporting Edible Films

by Bhupendra Singh (Assistant Director) Indian Institute of Packaging

At present the most commonly used packaging materials for food packaging are Metals, Glass, Plastics, Foil and Wax board containers for protection against external contamination, the effects of atmospheric oxygen and moisture, and for protection against mechanical damage. The food has to be removed or separated from the package at the time of use.

In contrast to this we can have packages in the form of films or coatings on the food product, which becomes an integral part of the food, the food can be consumed as such. These packages are known as edible packaging and they are the packaging materials of the future.

Edible films and coatings are protective barriers while also being an edible portion of the packaged or coated food. The protective functions served by the film include oxygen, moisture and aroma barriers, as well as physical damage prevention. Active ingredients and seasonings can be incorporated into the edible films and coatings. They may carry antioxidants, antimicrobial agents, colorants, flavors, fortified nutrients, and/or spices.

by- Bhupendra Singh

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Self Supporting Edible Films

An edible coating is a thin layer that is deposited on the surface of a food and is consumed. This layer is not self-supporting hence they are used to improve handling properties or to prevent moisture loss (wax coatings on fruits and vegetables). It is also used as an adhesive to seasonings on snack foods (e.g. salt on dry roasted peanuts) and to increase shelf life and reduce the need of packaging material. Wax coatings have disadvantages when used as moisture barriers since they tend to crack upon handling or with changes in temperatures. Most research on edible coatings has been done with cellulose ethers, starch, hydroxypropylated starch, corn zein, wheat gluten, soy protein and milk proteins

Development of the self-supporting edible films has been the subject of tremendous research since the last decade. The advantages is using the self-supporting edible films is that these films can be prepared by casting solutions of proteins, carbohydrates and lipids, in different combinations and compositions. Their properties are found to be affected considerably by different factors at different stages in the process.

Films made from natural products are gaining increasing scientific and commercial interest in self-supporting edible films. These films are not only biodegradable but may also be recyclable as well as acceptable for human consumption and pharmaceutical applications. Multiple uses, ease of disposal and the replacement of petroleum-based raw materials with renewable agricultural products make these types of films excellent materials for commercial development.

Various self- supporting edible films currently available are made from a variety of polysaccharides, vegetable proteins and lipids. Polysaccharides used in edible films include alginate, pectin, cellulose, modified cellulose, agar, carrageenan and starches among others. Proteins, other than collagen, used in making films or coatings for foodstuffs include gelatin, casein and albumin and various vegetable proteins such as wheat and corn gluten and soy. Lipid films used as coatings include fatty acid glycerides and various waxes such as paraffin and beeswax. Platicizer’s may also be included in the

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Self Supporting Edible Films

mixtures in order to increase film flexibility. The self-supporting edible films are advantageous in that all materials are derived from agricultural products.

The primary function of using edible film is to retard undesirable migration of moisture grease or oil and gaseous component (O2, CO2 or other volatile flavors), prevent the food from microbial invasion, mechanical damage and breakage and isolate reactive ingredients

Although most of the developed self-supporting edible films show desirable oxygen permeability, they still lack in moisture barrier and mechanical properties when compared with synthetic polymeric films.

Other benefits of using edible packaging materials as compared to ordinary packaging materials is as given below -

Their cost is generally low

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They reduce packaging waste as they become an integral part of the food and are biodegradable

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They can enhance the organoleptic, mechanical and nutritional properties of foods, as they are suitable for wrapping small pieces for portions of food.

They can also be used inside a heterogeneous food for providing barrier between the heterogeneous components.

These additional benefits together with tougher environmental legislation, consumer expectations for a variety of fresh foods, need for extended shelf life foods and opportunities for new foods with edible barriers have stimulated the interested in edible packaging.

The self-supporting edible films have a variety of applications. They are useful as coatings, adhesives, controlled release carriers or food wrappings. Edible films may also

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Self Supporting Edible Films

be used for such purposes as the fabrication of bags containing soup mixes that are added to boiling water for "instant" soup.

Films and fibers may also be prepared by a melt process, which involves mixing the components together with sufficient water to allow the pectin and starch to melt at a temperature below their decomposition temperatures. For making films, a tubular film can be made with cool air being blown through the center of the tube to both cool the film and to impart a biaxial stress to the film. The extrusion process can be utilized to make articles of varied shapes and profiles by using appropriate dies.

Self-supporting edible films having higher mechanical strength can easily be used as wrapper for low moisture and confectionery items. In food packaging the use of multilayer barrier films poses a problem during recycling, as each layer is difficult to separate.

By using pouches made from self-supporting edible films the problems associated with the recycling of the films can be overcome. Because of the tensile and mechanical strength of the product, conventional procedures such as printing and coating may be performed on the finished product, even in film form. This allows for edible products to be made with printing on the wrap, with the wrap itself being edible (and even flavored by inclusion of flavors into the fibrous material). Because of the water resistance of the materials, the wrap itself could be washed for sanitary purposes and the entire article, wrapper and all, eaten and digested.

Self-supporting edible films made from glucomannan can be casted in the form of a thin film on the surface of the sausage or it can be sprayed onto the sausage surface or extruded sausage can be passed through glucomannan solution.

The fast dissolving orally consumable self-supported edible films can be used to deliver breath deodorizing agents, antimicrobial agents and salivary stimulants to the oral cavity. The films can also be used to deliver pharmaceutically active agents. The konjac flour

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Self Supporting Edible Films

gels have been reported for use as self-supporting edible films for use as a collagen replacement.

Though the concept of using self- supporting edible films seems to be simple the total replacement of the synthetic packaging materials still needs lots of research inputs as well as government support. The development of these films is still in nascent stage but it will see a bright future.

References: 1. Chen; L., Ruan; R. R., Johnson; J. E., Addis; P. B., Xu; Li, Yi,; L., U. S. Patent 5,817,381 (1998) 2. Fishman; M. L. and Coffin; D. R., U. S. Patent 5,451,673 (1995) 3. Merritt, II F. M., U. S. Patent 5,962,053 (1999) 4. Chen; L, Ruan R. R., Addis; P. B., Xu; Li, Yi,; L., U. S. Patent 6,083,582 (2000) 5. Averbach; B. L. U. S Patent 5,130,150 (1992) 6. Averbach; B. L. U. S Patent 5,130,151 (1992) 7. Wageningen University, Department of Agrotechnology and Food Sciences. Processing of Agricultural Raw Materials for Non-Food Products. P050-217 8. Leung; S. H. S., Leone; R. S., Kumar; L. D., U. S. Patent 6,596,298 (2003) 9. Merritt, II F. M., U. S. Patent 5,695,800 (1997)

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