CC BY
12УДК 664.9.03
Saman Azizizadeh1, Mohammadyar Hosseini*1, Somayeh Aziznia2, Mohammad Ali Shariati3 1. Department of Food Science and Engineering, Faculty of Agriculture, Urmia University, Urmia, Iran
samanazizizadeh2172@gmail.com 2. Department of Food Science and Engineering, Faculty of Agriculture, Ilam University, Ilam, Iran.
3. Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran.
* Corresponding author email: hosseini1701@gmail.com
BIODEGRADABLE PACKAGES;
GOOD REPLACER OF SYNTHESIZED PACKAGES FROM OIL COMPOUNDS
(Биоразлагаемые пакеты - заменитель синтезированных пакетов из нефтяных соединений)
Abstract
In recent years, using of biodegradable materials instead of synthetic oil materials has been growingly increased with no non biodegradation and non recycling properties of oil compounds. These biopolymer materials produce through interactions in animals, plants and microorganism. In this study we have reviewed the advantages and disadvantages of biopolymers and their production in details.
Key words: biopolymer, packaging, biodegradability, film.
В последние годы взамен синтетическим материалам имеет тенденцию к увеличению использование био-разлагаемых материалов, не являющихся продуктами переработки соединений нефти. Эти биополимерные материалы производятся посредством использования животных, растений и микроорганизмов. В данном исследовании рассмотрены преимущества и недостатки биополимеров, а также их производство в деталях.
Ключевые слова: биополимер, упаковка, биоразлагаемость, пленка.
Introduction
Almost nearly all of the daily purchased products contain packaging and their packing is due to keeping products from possible physical damages and contamination, identification of products, information about products, optimizing of distribution costs and preparation of more convenient for consumers (1).
The main part of produced packages product are related to foodstuffs in the world. Films categorizes as one of the packaging materials. A suitable film must satisfy the requirements:
• Providing calm and controlled respiration for product.
• Providing the possibility of specific inhibition for carbon dioxide and steam.
• Creating modified atmosphere in order to adjust the respiration and improving shelf life.
• Reduction of fat migration (in confectionary products).
• Keeping the structure of foodstuffs from mechanical damages.
• Carrier of additives such as flavor, color, anti-oxidant, anti microbial etc.
• Preventing or reduction of microbial spoilage when storage.
• Keeping of moisture of foodstuffs and prevent from removing oxygen and aroma (2,3,4 and 5)
The disadvantages of using of synthetic plastic from oil compounds
Annually, more than 150 million ton derived synthetic plastic produced in which the most part is disposable plastics (6). Packages used in industries include two third of all packaging trashes (7).
Using of derived plastic from oil compounds like poly olefins, poly esters, poly amids etc has been gro-wingly increased as a result of availability, low price, and low weight, appropriate functional properties (expandability, resistant to tear, inhibition properties and high heat resistance) in recent 20 years. Reversely, these compounds contain lower steam penetration rate than water and are hydrophobic therefore biodegradability is their main challenge. Food packaging must degrade with no remained waste in a reasonable certain time (5).
Most plastics derived from oil compounds are resistance to biological attacks as a result of not being present of decomposing enzyme by microorganisms, besides their hydrophobic nature prevent enzyme activities. Biodegra-dability starts when microorganism begins growth on polymer surface and release polymer decomposing enzymes. This reaction depends on lots of parameters including microorganism activity, surface polymer ratio, Temperature, pH, molecular weight of polymer and its crystals state (1).
Keeping and storing of plastic waste in ground require a wide range of ground, burning them also releases carbon dioxide and may not consider a good way. Hence their remained wastes result in the pollution of environ-
ment (2, 7, 8, 9, 10, and 11). Moreover using of hard polymers in short term packaging is not of being appropriate (12).
Biodegradable packaging Biodegradability
The problem of waste material has been resulted in focusing of scientists on the production of biodegradable packages, the materials degrade quickly in nature, mineralize and absorb.
Biodegradability is a natural processing where organic compounds decompose to more simple products like carbon, nitrogen and sulfur (13).
Base on ASTM 6400-9 definition, biodegradable term refers to materials which produce by bacteria, yeasts, fungi, algae in aerobic, water and carbon dioxide and methane condition. Compost-able plastics convert to water, carbon dioxide and non organic materials and don't remain toxic waste.
Biopolymers; good replacer of synthetic polymers
Since biopolymers have no problem of remained waste like plastics and classified as biodegradable may consider as good replacer of derived synthetic polymers from oil materials. They are a apart of ecosystem (6, 18).
Biopolymers are polymers produced through the biochemical interaction in animals, plants and microorganism in nature. Biodegradable polymers categorized in 4 groups;
• Agro polymers (poly saccharide) derive from biomass such as starch, cellulose, protein
• Polymers such as poly hydroxyl alconate (PHA) produced from microorganism activity
• Synthetic polymers of monomers came from recycled sources such as poly lactic acid (PLA) made from lactid
• Polymers produced from monomer of fossils origins but degradable by enzymes such as poly prolacton (PCL), poly ester amide (PEA), Co polyester aromatic or aliphatic (6, 19).
Suitable bio polymers must include characteristics such as strong, appropriate flexibility, non toxic, non penetrate to oxygen, resistant to wet penetration and low cost of raw material and processing (10).
The advantages of biopolymers in comparison with synthetic polymers are biodegradability and recycling. However weak mechanical properties and inhibition to steam limit their application in industries.
Polysaccharides are appropriate inhibitors for gas, aroma and fat. They also good inhibitor of oxygen in low and medium relative humidity and exhibits good mechanical properties in this range of relative humidity. However their inhibition is weak as a result of their hydrophilic nature (4, 20).
Different groups of biopolymers such as polysaccha-rides and proteins (zein and gluten) and lignin are available where polysaccharides such as cellulose, starch are the most of them (12).
Properties and defects of biodegradable polymers
Mostly biodegradable polymers contain excellent properties in comparison with derived plastic from oil compounds and will be compete able with plastic goods.
Thus biodegradable polymers have a high potential in commercializing and forming to bioplastics. But some properties such as high penetrate ability of steam, crashing restrict their applications in wide range. Therefore their modification seems essential (13).
Providing film methods
Biopolymers film is a three dimensional matrix which produces by two dry and wet methods (4).
Dry method
This method is base on thermoplastic process of some biopolymers. In this method biopolymers heat up to more than glass transition temperature in low wet by extrusion or thermo compression method. This heating cause to soften polymers and let them to change their form after cooling. The drying process usually applies for pre preparation of biomaterial, thermoplastic starch and proteins. In this method other processes such as extrusion, molding. However this method needs lots of equipment, this method has some advantages in comparison with wet process including being more industrial like process, producing a matrix with high wide linkages and reduction of produced film solution (4).
Wet process
This method commonly known as solvent casting and basically refers to drying of prepared solution from polymer. This method is the most usual way of film production including stages of solving, casting and drying. First stage is the preparing film solution by dissolving of biopolymer in an appropriate solvent like water, alcohol or organic alcohol. However appropriate solvent of foodstuffs like water, ethanol or mixture of both uses in production of edible film. Nest stage is the drying of solution. In production of an integrate film, the strong interaction between biopolymers in creating of a 3 dimensional critical integrate matrix is an obligation. The type and amount of interactions differ from polymer type, film production conditions, Drying Temperature, drying rate, moisture content, solvent type, softening concentration, different pH. Casting solvent method mostly applied for providing of biopolymer films (4, 21).
Conclusion
Since biopolymers have no problem of waste remained from plastic material and consider biodegradable may be suitable replacement of oil compounds. They also won't cause of carbon dioxide accumulation after carbon cycle and are of a part of ecosystem. The advantages of biopolymers in comparison with synthetic polymers are being their biodegradability and recycling.
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Поступила в редакцию: 02.09.2014 г.
Saman Azizizadeh - Department of Food Science and Engineering, Faculty of Agriculture, Urmia University, Urmia, Iran, samanazizizadeh2172@gmail.com
