BIODEGRADABLE AND EDIBLE PACKAGING MATERIALS

BIODEGRADABLE AND EDIBLE PACKAGING MATERIALS

INTRODUTION

Plastics are being used all over the world. From drinking cups and disposable silverware to parts for automobiles and motorcycles, plastics are continuing to rise. Plastics have been an environmental trepidation because of the lack of degradation. Plastics make up about 20% by volume waste per year. There are over 21,000 plastics facilities in the world, and the employment rate has increased by an average of three percent over the past two and a half decades. Plastics are extremely important to the job market as well as packaging throughout the world. Since plastics are vital to people’s everyday lives, production of biodegradable plastics to make plastics more compatible with the environment is necessary.

Packaging of food that was considered a luxury and source of cost addition in the yesteryears has now become a necessity and source of value addition .But considerable quanta of used packaging material being non biodegradable become a source of visible nuisance and toxic substances that are accidental byproducts of improper disposal of non biodegradable packaging materials are source of concern. Increasing environmental issues, awareness among consumers and growing market of convenience food have increased the need for development of biodegradable packaging materials.

BIO-DEGRADABLE PACKAGING

Biodegradable polymers are a newly emerging field. A vast number of biodegradable polymers have been synthesized recently and some microorganisms and enzymes capable of degrading them have been identified. In developing countries, an environmental pollution bysynthetic polymer has assumed dangerous proportions. As a result, attempts have been made to solve these problems be including biodegradability into polymers in everyday use through slight modifications of their structures.

Biodegradation is a natural process by which organic chemicals in the environment are converted to simpler compounds, mineralized and redistributed through elemental cycles such as the carbon, nitrogen and sulphur cycles. Biodegradation can only occur within the biosphere as microorganisms play a central role in the biodegradation process. Biodegradable polymers are useful for various applications in medical, agriculture, drug release and packaging fields.

Brief History

Biodegradable plastics began being sparking interest during the oil crisis in the 1970’s. As oil prices increased, so did the planning and creating of biodegradable materials. The 1980’s brought items such as biodegradable films, sheets, and mold forming materials. Green materials (or Plant-based) have become increasingly more popular (Mohanty, 2004). This is due impart to the fact that they are a renewable resource that is much more economical then they were in the past

Purpose and Needs of Biodegradable Materials

“Annual expenditure on packaging increased by more than 4% between 1994 and 1996”, according to a report from Pira, the UK packaging consultancy. “Plastic’s share of the total packaging expenditure remained constant over the same period, at 29%”. Since there is an abundant amount of waste in the world, there has been a lot of interest in research devoted to the creating of biodegradable materials.

There are many advantages to creating the biodegradable plastics. Starch-based plastics have been proved to be more environmentally friendly. Starch-based biodegradable plastics have been shown to degrade 10 to 20 times faster than traditional plastics. When traditional plastics are burned, they create toxic fumes which can be damaging to people’s health and the environment. If any biodegradable films are burned, there is little, if any, toxic chemicals or fumes released into the air. Biodegradable plastics have been proved to improve soil quality. This process is performed as the microorganisms and bacteria in the soil decompose the material, and it actually makes the ground more fertile

NATURAL BIODEGRADABLE POLYMERS

Biopolymers are polymers formed in nature during the growth cycles of all organisms; hence, they are also referred to as natural polymers. Their synthesis generally involves enzyme-catalyzed, chain growth polymerization reactions of activated monomers, which are typically formed within cells by complex metabolic processes.

Polysaccharides

ü Starch

Starch is a polymer which occurs widely in plants. Starch based plastics are mainly harvested from wheat, potatoes, rice, and corn.. Starch has been widely used as a raw material in film production because of increasing prices and decreasing availability of conventional film-forming resins. Starch films posses slow permeability and are thus attractive materials for food packaging.

ü Cellulose

Cellulose was isolated for the first time some 150 years ago.Cellulose differs in some respects from other polysaccharides produced by plants, Themolecular chain being very long and consisting of one repeating unit (cellobiose). Cellulose has received more attention than any other polymer since it is attacked by a wide variety of microorganisms, and since it is often used in textiles without additives to complicate the interpretation of results. The biodegradation of cellulose is complicated, because cellulose exists together with Lignin.

ü Chitin and chitosan

Chitin is a macromolecule found in the shells of crabs, lobsters, shrimps and insects. Chitin can be degraded by chitinase. Chitin fibres have been utilized for making artificial skin and absorbable sutures. Modified chitosans have been prepared with various chemical and biological properties. Chitin derivatives can also be used as drug carriers.

Polypeptides of natural origin

ü Gelatin

Gelatin, an animal protein, consists of 19 amino acids joined by peptide linkages and can be hydrolyzed by a variety of the proteolytic enzymes to yield its constituent amino acids or peptide components. Gelatin is a water-soluble, biodegradable polymer with extensive industrial, pharmaceutical and biomedical uses, has been employed for coatings and microencapsulating various drugs, and for preparing biodegradable hydro gels.

ü Bacterial polyesters

The natural polyesters, which are produced by a wide variety of bacteria as intracellular reserve materials, are receiving increased attention for possible applications as biodegradable; melt processable polymers which can be produced from renewable resources.

FACTORS AFFECTING BIODEGRADATION

v Effect of polymer structure

Natural macromolecules, e.g. protein, cellulose, and starch are generally degraded in biological systems by hydrolysis followed by oxidation. It is not surprising, then, that most of the reported synthetic biodegradable polymers contain hydrolysable linkages along the polymer chain; for example, amide enamine, ester, urea, and urethane linkages are susceptible to biodegradation by microorganisms and hydrolytic enzymes. Since many proteolytic enzymes specifically catalyze the hydrolysis of peptide linkages adjacent to substituent in proteins, substituted polymers containing substituent such as benzyl, hydroxyl, carboxyl, methyl, and phenyl groups have been prepared in the hope that an introduction of these Substituent might increase biodegradability

v Effect of polymer morphology

One of the principal differences between proteins and synthetic polymers is that proteins do not have equivalent repeating units along the polypeptide chains. This irregularity results in protein chains being less likely to crystallize. It is quite probable that this property contributes to the ready biodegradability of proteins. Synthetic polymers, on the other hand, generally have short repeating units, and this regularity enhances crystallization, making the hydrolysable groups inaccessible to enzymes. It was reasoned that synthetic polymers with long repeating units would be less likely to crystallize and thus might be biodegradable; indeed, a series of poly(amide-urethane)s were found to be readily degraded by subtilisin.

v Effect of radiation and chemical treatments

Photolysis with UV light and irradiation of polymers generate radicals and/or ions that often lead to cleavage and cross linking. Oxidation also occurs, complicating the situation, since exposure to light is seldom in the absence of oxygen. Generally this changes the material’s susceptibility to biodegradation

MODE OF BIODEGRADATION

1) Microorganisms

· Fungi

Eu mycetes, or true fungi, are microorganisms of particular importance in causing the degradation of materials. Fungi are nucleated, spore-forming, nonchlorophyllous organisms which reproduce both sexually and asexually; most of them possess filamentous, somatic structures, and cell walls of chitin and/or cellulose.

· Bacteria

Schizomycetes, a bacterium, have played an undetermined role in relation to fungi in polymer deterioration. Bacteria present in soil are important agents for material degradation. Particularly affected are cellulosic plant life, wood products, and textiles subject to cellulytic degradation

2) Enzymes

Enzymes are essentially biological catalysts, with the same action as chemical catalysts.

Enzymes are very specific in each reaction.

APPLICATIONS

Packaging

Physical characteristics of packaging polymers are greatly influenced by the chemical structure, molecular weight, crystalline and processing conditions of the polymers used. The physical characteristics required in packaging depend on what item will be packaged as well as the environment in which the package will be stored. Items which must be kept frozen for a period of time require special packaging. Food items require more stringent packaging requirements than nonperishable goods.

The challenge in the development of biodegradable packaging will be to combinepolymers which are truly biodegradable into a laminate film or a film blend which has properties as good as those found in synthetic laminates. For food applications, for example,it may be possible to coat food items with pullulan which has a very low oxygen permeabilityand is edible and to utilize PHBV as an outer packaging which has good flexibility and is amoisture barrier. A film blend of pullulan and PHBV can also be produced254 since bothpolymers can be melt blended under conditions were sufficient moisture is maintained during processing. The addition of pullulan to PHBV may reduce oxygen permeability and increase biodegradability of the blend due to the increased surface area of PHBV exposed following the rapid removal of pullulan due to its water solubility. Several polysaccharide-based biopolymers are being used as possible coating materials or packaging films. They include starch, pullulan and chitosan. The degradation of synthetic polymer films can be accelerated by incorporating starch as filler. LDPE blends with up to 10% corn starch was produced using conventional techniques and was made into bags for groceries or rubbish.

Medical applications

Biodegradable plastics have been developed as surgical implants in vascular and orthopedic surgery as implantable matrices for the controlled long-term release of drugs inside the body, as absorbable surgical sutures, and for use in the eye. Recently the term biomaterial was defined as a nonviable material used in medical device applications that is intended to interact with a biological system.

· Surgical sutures

· Bone fixation devices

· Vascular grafts

· Adhesion prevention

· Artificial skin

· Drug delivery systems

Agricultural applications

Since the introduction of plastic films in the 1930s and 1940s for greenhouse coverings, fumigation and mulching, agricultural applications of polymers have grown at an enormous rate. All principal classes of polymers, i.e. plastics, coatings, elastomers, fibres and watersoluble polymers are presently utilized in applications which include the controlled release of pesticides and nutrients, soil conditioning, seed coatings, gel plantings and plant protection.

· Agricultural mulches

Mulches permit growers to use plastic films to help with plant growth and then photodegrade

in the fields thereby avoiding the cost of removal.Controlled release of agricultural chemicals

Controlled release (CR) is a method by which biologically active chemicals are made available to a target species at a specified rate and for a predetermined time.

· Agricultural planting containers

A small niche for degradable plastics is the use of polycaprolactone for small agricultural planting containers. Although this is a small volume application for degradable plastics, it is presented here because it is one of the few applications in which the polymer used is biodegradable within a reasonable period of time.

Different biodegradable materials

Polylactic acid (PLA): PLA is produced from a renewable resource; corn. The corn is harvested and then milled to extract the starch from the raw materials. From the starch, dextrose is produced. The dextrose is then fermented, transforming into lactic acid Polylactic acid is the most used biodegradable material, because of its wide use range. It can be used for single use cutlery, cups, short-shelf life trays and even in bottles.

Polybutylenes succinate (PBS): Polybuthylenes succianate has been used almost for the same purposes than the PLA. Food packaging and film wrapping applications.

Poly3-hydroxybutyrate (PHB): It has very similar physical properties than Polypropyl- ene so it can be used in different kind of food packaging applications such as bottles, bags and wrapping films.

Polycaprolactone (PCL): It is widely used in medical purposes for now but in the future it can be possible that this material will be one of the packaging materials.

Plastarch material (PSM): Starch based material which is chemically derived to become a biodegradable plastic material, used in food trays, cups and single use cutlery.

EDIBLE PACKAGING

An edible coating or film could be defined as primary packaging made from edible components. In this process thin layer of edible material can be directly coated to a food or formed into a film and be used as a food wrap without changing the original ingredients or the processing method. Edible films and coatings have been used to improve the gas and moisture barriers, mechanical properties, sensory perceptions, convenience, and microbial protection and prolong the shelf life of various products.

History

The concept of employing edible films as protective coatings for foods to prolong storage life is not new. Coating of fresh oranges and lemons with wax to retard desiccation was practiced in China in the 12th and 13th centuries. Although the Chinese did not realize that the full function of edible coatings was to slow down respiratory gas exchange, they found that wax coated fruits could be stored longer than non-waxed fruits. In the 19th century, sucrose was initially applied as an edible protective coating on nuts, almonds, and hazelnuts to prevent oxidation and rancidness during storage. In the 1930s, hot-melt paraffin waxes became commercially available as edible coatings for fresh fruits as apples and pears, and in the 1950s carnauba wax oil-in-water emulsions were developed for coating fresh fruits and vegetables, to improve their appearance, such as their shininess, color, softening, carriage of fungicides, and to better control their ripening and to retard the water loss. Patents on edible films to extend the shelf-life of foods date back to the 1950s, comprising films for frozen meat, poultry and seafood using alginates, fats, gums and starches.

REQURMENTS OF EDIBLE FILMS AND CAOTING

v Should prevent the product dehydration.

v Should control the transmission of gases, vapors and solutes.

v Should provide mechanical protection to foods.

v Should have good mechanical properties.

v Should serve as a carrier for additives, viz. antioxidant, antimicrobial agents, flavors, colorings, nutrients etc.

v Composition should conform to the regulations those apply to the food product concerned.

MATERIALS FOR EDIBLE PACKAGING

The main film forming materials are biopolymers such as proteins, polysaccharides, lipids, resins. They can be used alone or combinations.

PROTEINS

They are commonly used films forming materials. They are macromolecules with specific amino acid sequence and molecular structures. The secondary, tertiary and quaternary structures of protein can be modified by heat treatment, pressure, irradiation, mechanical treatment, acids, alkali, metal ions, salts, chemical hydrolysis, enzymatic treatments and chemical cross linking. Protein film forming materials are derived from many different animal and plant sources such as animal tissue, milks, eggs, grains and oil seeds. There are different proteins like milk proteins, wheat gluten, corn proteins, s etc.

Milk protein

Casein is the major protein in milk. Highly concentrated casein solutions gelatinized using Trans glutaminase resulting in film with favourable tensile property.Trans glutamine is a calcium dependent enzyme that catalyses the formation of covalent glutamyl-lysyl cross links.Films are insoluble in water,mercaptoethanol and guanidne hydrochloride. Pure caseinate films are attractive for use in food product due to their transparent and flexible nature and water solubility.

Wheat protein

Wheat proteins films are brittle due to extensive intermolecular forces.
plasticizers reduce these forces and increase the mobility of biopolymer chains and thereby improve the mechanical properties of the films. However the resulting loose structure reduce the ability of film to act as a barrier to diffusion to various gases and vapours .The greatest obstacle to commercial exploitation of wheat gluten film appears to be their high water permeability.Edible food packaging films and sausages castings are made from blends collagen and gluten using filters and softening agents.

Corn protein

Zein is the only protein that continues to be produced commercially.It is characterized by ability to form tough, glossy, hard greaseproof coating after evaporation of the aqueous alcoholic solvent. Zein coatings for pharmaceuticals labels and candies are formed by spraying or dipping the product into aqueous ethyl alcohol or isopropyl alcohol solution of Zein.The solution also contain FDA approved plasticizer viz. glycerin ,propylene glycol or acetataldehyde glycerides.

POLYSACCHARIDES

Polysaccharide films are made from starch, alginate, cellulose ethers, chitosan, carageenan, or pectins and impart hardness, crispness, compactness, thickening quality, viscosity, adhesiveness, and gel forming ability to a variety of films. These films because of the makeup of the polymer chains exhibit excellent gas permeability properties, resulting in desirable modified atmospheres that enhance the shelf life of the product without creating anaerobic conditions. Additionally, polysaccharide films and coatings can be used to extend the shelf-life of muscle foods by preventing dehydration, oxidative rancidity, and surface browning, but their hydrophilic nature makes them poor barriers for water vapour .

Starch:

Starch is composed of amylose and amylopectin, is primarily derived from cereal grains like corn (maize), with the largest source of starch. Other commonly used sources are wheat, potato, tapioca and rice. Starch is the major carbohydrate reserve in plant tubers and seed endosperm where it is found as granules, each typically containing several million amylopectin molecules accompanied by a much larger number of smaller amylose molecules.

Amylose is responsible for the film forming capacity of starch .High amylose starch films have been made that are flexible, oxygen impermeable, oil resistant, heat-sealable, and water soluble. Films of high-amylose corn starch or potato starch was more stable during aging .Starch-based films exhibit physical characteristics similar to plastic films in that they are odorless, tasteless, colorless, non-toxic, biologically absorbable, semi-permeable to carbon dioxide, and resistant to passage of oxygen. Since the water activity is critical for microbial, chemical, and enzymatic activities, edible starch based films can retard microbial growth by lowering the water activity within the package.

Alginates

Alginates are derived from seaweeds and possess good film-forming properties that make them particularly useful in food applications. Alginate has a potential to form biopolymer film or coating component because of its unique colloidal properties, which include thickening, stabilizing, suspending, film forming, gel producing, and emulsion stabilizing Divalent cations (calcium, magnesium, manganese, aluminum, or iron) are used as gelling agents in alginate film formation. Desirable properties attributed to alginate films, include moisture retention, reduction in shrinkage improved product texture, juiciness, color, and odor of foods. Edible films prepared from alginates form strong films and exhibit poor water resistance because of their hydrophilic nature

Carrageen:

Carrageen is water-soluble polymer with a linear chain of partially sulphated galactans, which present high potentiality as film-forming material. These sulphated polysaccharides are extracted from the cell walls of various red seaweeds (Rhodophyceae). Carrageenan film formation includes agelation mechanism during moderate drying, leading to a three-dimensional network formed by polysaccharide - double helices and to a solid film after solvent evaporation recently, carrageenan films were also found to be less opaque than those made of starch. Carrageenan is extracted from red seaweed

Cellulose Derivatives:

Cellulose derivatives are polysaccharides composed of linear chains of β (1–4) glucosidic units with methyl, hydroxypropyl or carboxyl substituents. Only four cellulose derivative forms are used for edible coatings or films:Hydroxypropylcellulose , hydroxypropyl methylcellulose , Carboxymethylcellulose or Methyl cellulose. Cellulose derivatives exhibit thermo-gelation. Therefore when suspensions are heated they form a gel whereas they return to their original consistency when cooled. However, cellulose derivative films are poor water vapour barriers because of the inherent hydrophilic nature of polysaccharides and they possess poor mechanical properties. One method in enhancing the moisture barrier would be by incorporation of hydrophobic compounds, such as fatty acids into the cellulose ether matrix to develop a composite film.

Pectin:

Pectins are a group of plant-derived polysaccharides that appear to work well with low moisture foods, but are poor moisture barriers. Pectin is a heterogeneous grouping of acidic structural polysaccharides, found in fruit and vegetables and mainly prepared from citrus peel and apple pomace. This complex anionic polysaccharide is composed of β-1,4-linked D-galacturonic acid residues, wherein the uronic acid carboxyls are either fully or partially methyl esterified.

Agar:

Agar is a hydrophilic colloid consisting of a mixture of agarose and agaropectin that have the ability to form reversible gels simply by cooling a hot aqueous solution. Used extensively in microbiological media to provide firmness, agar exhibits characteristics that make it useful for coating meats. It forms strong gels characterized by melting points far above the initial gelation temperature (. Agar gel melts on heating and resets on cooling. Because of its ability to form very hard gels at very low concentrations and the simplicity of the extraction process, agar has been used extensively as a gelling agent in the food industry. However, despite its biodegradability and its enormous gelling power, agar has not been used widely due to poor aging. Both photodegradation and fluctuations in ambient temperature and humidity alter agar crystallinity, leading to formation of micro-fractures and polymer embrittlement.

Chitin/Chitosan:

Chitosan is an edible and biodegradable polymer derived from chitin, the major organic skeletal substance from crustacean shells. This is the second most abundant natural and non-toxic polymer in nature after cellulose.Some desirable properties of chitosan are that it forms films without the addition of additives, exhibits good oxygen and carbon dioxide permeability, as well as excellent mechanical properties and antimicrobial activity against bacteria, yeasts, and molds. However, a major drawback of chitosan is its poor solubility in neutral solutions. Chitosan products are highly viscous, resembling natural gums. Chitosan can form transparent films to enhance the quality and extend the storage life of food products. Pure chitosan films are generally cohesive, compact and the film surface has a smooth contour without pores or cracks.

Gums:

Gums in edible-film preparation are used for their texturizing capabilities. All gums are polysaccharides composed of sugars other than glucose. Gums are differentiated into three groups: exudate gums (gum Arabic; mesquite gum), the extractive gums (from endosperm of some legume seeds or extracted from the wood: guar gum) and the microbial fermentation gums (xanthan gum). In edible-forming preparations, guar gum (E 412) is used as a water binder, stabilizer and viscosity builder. Gum arabic (E 414), owing to its solubility in hot or cold water, is the least viscous of the hydrocolloid gums. Xanthan gum is readily dispersed in water; hence high consistency is obtained rapidly in both hot and cold systems. A blend of guar gum, Arabic and xanthan gum provided uniform coatings with good cling and improved adhesion in wet batters. The mesquite gum forms films with excellent water vapor barrier properties when small amounts of lipids are added in their formulation.

ü xanthan gum is a naturally occurring anionic Polysaccharides extracted from a bacterium called Xanthomonas compestris

ü Gum Arabic is an oldest well established anionic polysaccharides extracted from the sap of specific trees and bushes. Gum arabic consists of a chain of galactose sugars.

Lipid

Lipid compounds utilized as protective coating consist of acetylated monoglycerides, natural wax, and surfactants. The most effective lipid substances are paraffin wax and beeswax. The primarily function of a lipid coating is to block transport of moisture due to their relative low polarity. In contrast, the hydrophobic characteristic of lipid forms thicker and more brittle films. Consequently, they must be associated with film forming agents such as proteins or cellulose derivatives. Generally, water vapor permeability when the concentration of hydrophobicity phase increases. Lipid-based films are often supported on a polymer structure matrix, usually a polysaccharide, to provide mechanical strength.

Waxes and paraffin

Paraffin wax is derived from distillate fraction of crude petroleum and consists of a mixture of solid hydrocarbon resulting from ethylene catalytic polymerization. Paraffin wax is permitted for use on raw fruit and vegetable and cheese. Carnauba wax is an exudate from palm tree leaves (Copoernica cerifera) . Beewax (white wax) is produced from honeybees. Candelilla is obtained from candelilla plant. Mineral oil consists of a mixture of liquid paraffin and naphtheric hydrocarbon Waxes are used as barrier films to gas and moisture (skin on fresh fruits) and to improve the surface appearance of various foods (e.g., the sheen on sweet). If applied as a thick layer, they must be removed before consumption (certain cheese); when used in thin layers, they are considered edible. Waxes (notably paraffin, carnauba, candellila and bee wax) are the most efficient edible compounds providing a humidity barrier

PROPERTIES OF EDIBLE PACKAGING

v Barrier properties

One of the functions of packaging is to act as a barrier that separates and protects the product from exposure to the environment. Edible films have been commercially used to protect meat, fruits, and vegetables from pathogenic microbial contamination. Other functions include the barrier to moisture, oxygen and other gases, fats and oils. These barriers can be applied to ready-to -eat food and fresh produce such as fruits and vegetables. However, environmental conditions, such as temperature, relative humility and the stress of handling the product by consumers can influence the barrier performance of the package.

v Carrier properties

During the raw material blending process, active compounds can be added to edible films and coating solutions. These include antioxidants, antimicrobial agents, flavoring, pigments and nutrients. In such cases, the functional groups from the edible material would be bonded to the additives within the polymeric matrix. For example, nisin added to alginate edible films showed antimicrobial activity against Staphylococcus when applied to beef. Pigment additives carried by edible materials could improve the appearance of selected products during storage.

v Enhancement properties

The ability of edible coating to improve the mechanical properties of some fragile products has been previously discussed. However, protein and carbohydrate-based edible materials have less tensile strength because of their strong cohesive energy density. Because of this, they tend to form brittle films without the addition of plasticizers. However, this property could be used to provide a hard shell-like protective to the outer layer to certain products. Examples of plasticizers that could be used in these films include glycerol, mannitol and sorbitol. Edible coating may also enhance the appearance andflavor of a product. The wax on fruits (e.g. lemons, oranges, apples) polishes the surface and makes the product appear glossy. It also acts as a moisture barrier that reduces wilting of the product

ADVANTAGES OF EDIBLE PACKAGING

v Can be consumed with packed product

v No disposal problem, hence eco friendly

v Can be produced exclusively from renewable edible ingredients and anticipated to degrade mere readily than polymeric materials.

v Can enhance the organo leptic properties of packed product by providing flavour, colour, and sweetness to them.

v Can supplement the nutritional value of foods.

v Can be tailored to prevent deteriorative inter component moisture and solute migration in foods such as pizzas, pies and canies.

v Can used in multi layer food packaging materials together with non edible films.

v Can function as carrier for antimicrobial and antioxidant agents.

v Can control the diffusion rate of preservative substances from the surface to the interior of the food.

v Can be used for microencapsulation of food flavourings.

Conclusion

An edible film is defined as a thin layer, which can be consumed, coated on a food or placed as barrier between the food and the surrounding environment. The most familiar example of edible packaging is sausage meat in casing that is not removed for cooking and eating. Such films can mechanically protect foods, prevent the contamination from microorganisms, prevent quality loss of foods due to mass transfer (e.g. moisture, gases, flavors, etc.). Considerable attention has been given to edible food packaging, which is intended to be an integral part of and to be eaten with the food product; thus, they are also inherently biodegradable.

Packaging waste forms a significant part of municipal solid waste and has caused increasing environmental concerns, resulting in a strengthening of various regulations aimed at reducing the amounts generated In recent years, there has been a marked increase in interest in biodegradable materials for use in packaging, agriculture, medicine, and other areas in India. General statement regarding the breakdown of polymer materials is that it may occur by microbial action, photo degradation, or chemical degradation.

In generally all the biodegradable packaging materials are belonging under polymers. Synthetic plastics are resistant to degradation, and consequently their disposal is fuelling an international drive for the development of biodegradable polymers.

REFERENCE

· Biodegradeable plastics “could replace landfills with compost heaps”Vol. 43, Iss. 12; pg. 6. BioCycle. Emmaus: Dec 2002. 16 Feb. 2004(Replace Landfills, 2002).

· Muzzarelli, R. A. A., Chitin in Nature and Technology. Plenum Press, New York, 1986

· Eastoe, J. E. and Leach, A. A., in The science and Technology of Gelatin, ed. A. G. Ward and A.Courts. Academic, New York, 1977, p. 73.

· Fukuda, K., An overview of the activities of the Biodegradable Plastic Society, in Biodegradable Polymers and Plastics, ed. M. Vert et al. Royal Society of Chemistry, 1992, p. 169[3] Johnson, R.M., Biopolymers, Smithers Rapra, 01/2003, pages 4-15

· National Research Council Staff, Biobased Industrial Products: Research and commercialization Priorities, National Academies Press, 02/1999, pages 55-74.

· Ahvenainen, R., Novel Food Packaging Techniques, Woodhead Publishing, Limited, 01/2003, pages 519-533. Krochta JM (2002) Proteins as Raw Materials for Films and Coatings: Definitions, Current Status, and Opportunities. In: Protein-Based Films and Coatings. CRC Press, New York.

· Janjarasskul T, Krochta JM (2010) Edible packaging materials. Annu Rev FoodSci Technol 1: 415-448.

· Mei Y, Zhao Y, Yang Y, Furr HC (2002) Using Edible Coating to Enhance Nutritional and Sensory Qualities of Baby Carrots. J Food Sci 67: 1964-1968.

· Murray, J. F.C., Limited, H. and Reigate. 2000. Cellulose.In Phillips, G.O. and Williams, P.A. (Eds.). Handbookof hydrocolloids, p 219-245. Cambridge, England:Woodhead Publishing Limited.

· Greener, I.K. and Fennema, O. 1989. Barrier properties and surface characteristics of edible, bilayer films. Journal of Food Science 54(6): 1393–1399

· Ribeiro, C., Vicente, A.A., Teixeira, J.A., and Miranda, C. 2007. Optimizationof edible coating composition to retard strawberry fruit senescence. Postharvest Biology and Technology 44(1): 63–70.

· Bourtoom, T.2008, Edible films and coatings: characteristics and properties, International Food Research J. 15(3):1-8.

· Rhim, J. W. LWT-Food Sci. Technol. 2004, 37, 323–30.

· Williams, P. A.; Phillips, G. O. In Handbook of hydrocolloids; Phillips G.; Willians P.; Ed.; CRCPress, Cambridge, England, 2000; pp 1-19.

· Park, S. Y.; Marsh, K. S.; Rhim, J. W. J. Food Sci. 2002, 67, 104–197.

· Krochta, J.M. 2002. Protein as raw materials for films and coatings: Definitions, current status, and opportunities. In Protein-Based Films and Coatings, ed. A. Gennadios, pp. 1–41. Boca Raton, FL: CRC Press

· Krochta JM (2002) Proteins as Raw Materials for Films and Coatings: Definitions, Current Status, and Opportunities. In: Protein-Based Films and Coatings. CRC Press, New York.