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Polymeric films with antimicrobial properties

Identification

Key words Active packaging, food packaging, antimicrobials, immobilization, active films, lysozyme, chitosan, nisin
Latest version 2011/10/18
Completed by SP

How does it work?

Primary objective Inhibiting growth of selected microorganisms on food surfaces and thus extend shelf-life of the food product.
Working principle Films with antimicrobial properties can be prepared to improve food safety and shelf life. Active biomolecules such as chitosan, nisin, lysozyme and other enzymes, chelators and metal ions can be either formed or incorporated into films.

For example, chitosan based polymeric material can be formed into films, fibres, gels, beads and nano-particles and has high antimicrobial activity against different microorganisms (5) and LDPE films has successfully been coated with nisin with antimicrobial activity against S. aureus and L. Monocytogeneses (6). Antimicrobial films can also be prepared from modified biodegradable materials such as polysaccharide- and protein-based material (7).

Incorporation of antimicrobial agents into films can enable slow release of the antimicrobials by diffusion and a concentration necessary for inhibiting bacterial growth on the surface can be maintained over time (1,3). The structure of the films is important in order to achieve a controlled release of the antimicrobial agent (3). An active compound can also be immobilized onto the polymeric material and act without being released e.g. immobilization of lysozyme on cellulose triacetate film gives high antimicrobial activity (2,3,6). However, the antimicrobial activity of an enzyme might be reduced after immobilization due to possible changes in the conformation of the enzyme (1,2). Immobilization of antimicrobials requires functional groups on both the antimicrobial compound and polymer (1,2,3).

Antimicrobial packaging films can be prepared by thermal polymer processing for heat-resistant agents (peptides etc.) or solvent compounding can be used as a method for heat sensitive antimicrobials like enzymes. Though, both the antimicrobial and the polymer need to be soluble in the same solvent during the solvent compounding process.

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Additional effects Reduced recontamination of processed food.

Film sterility during storage of foods.

Important process parameters
Important product parameters • Structure design of the polymer film to enable controlled release.

• Mechanical properties of the film: tensile strength.

• Concentration of antimicrobials in the polymer films, the antimicrobial may change the mechanical and optical properties.

• The effect of film thickness on activity, the diffusion rate is dependent on the thickness of the film.

What can it be used for?

Products Bread, meats, cheese, milk, fruit juices, pastry dough.
Operations Packaging.
Solutions for short comings Improve food safety and shelf-life, reduce the growth of specific microorganisms on the food surface and reduce recontamination of processed food.

What can it NOT be used for?

Products When a bioactive agent is immobilized onto the film surface this is a non-migrating system and requires contact between the food and the packaging material.
Operations Thermal processing can only be used for temperature stable antimicrobials and films.
Other limitations The structure of the films is important in order to achieve a controlled release of the antimicrobial agent and these studies are limited for food applications.

If the antimicrobial agent is non-volatile, the film needs to be in contact with the food product in order to diffuse to the surface. Other limitations could be that denaturation of proteins and enzymes by solvents may result in low activity of agent.

Risks or hazards The antimicrobial agent used needs to be safe for human consumption. Toxicity test needs to be performed.

Migration behavior of the compounds should be evaluated.

Implementation

Maturity Studies on films with controlled released properties are limited. Controlled released systems have mainly been developed for pharmaceutical applications.

Example of commercial antimicrobial materials are Nisaplin®, silver substituted zeolite and Zeomic®.

Modularity /Implementation The packaging line does not need to be changed.
Consumer aspects There is an increasing demand for minimally processed products and low preservative levels in the food and therefore this method is of interest.
Legal aspects In Europe: Commission regulation (EC) No 450/2009 of 29 May 2009 on active and intelligent materials and articles intended to come into contact with food.

In the US: The antimicrobials are considered as food additives since they may migrate into the food product and must meet the food additives standards (1).

Should be approved by the FDA (Food and Drug Administration).

Environmental aspects A polymer material (containing the antimicrobial agent) made from biodegradable polymers can reduce environmental impacts (e.g. chitosan).

Further Information

Institutes IMCB Institute for composite and biomedical materials
Companies Kraft Foods, Sinanen Zeomic, Agion
References 1. Appendini, P., Hotchkiss, J. H. (2002). Review of antimicrobial food packaging. Innovative Food Science & Emerging Technologies, 3, 113-126.

2. Conte, A., Buonocore, G.G., Sinigaglia, M., Del Nobile, M.A. (2007). Development of immobilized lysozyme based active film. Journal of Food Engineering, 78, 741-745.

3. Gemili, S., Yemenicioglu, A., Altinkaya, S. A. (2009). Development of cellulose acetate based antimicrobial food packaging materials for controlled release of lysozyme. Journal of Food Engineering, 90, 453-462.

4. Lee, C.H., Park, H.J., Lee, D.S. (2004). Influence of antimicrobial packaging on kinetics of spoilage microbial growth in milk and orange juice. Journal of Food Engineering, 65, 527-531.

5. Dutta, P.K., Tripathi, S., Mehrotra, G.K., Dutta, J. (2009). Perspectives for chitosan based antimicrobial films in food applications. Food Chemistry 114, 1173-1182.

6. Suppakul, P., Miltz, J., Sonneveld, K., Bigger, S.W. (2003). Active Packaging Technologies with Emphasis on Antimicrobial Packaging and its Application. Journal of Food Science 68, Nr. 2, 408-420

7. Kuorwel, K. K., Cran, M. J., Sonneveld, K., Miltz, J., Bigger, S. W., (2011). Antimicrobial activity of biodegradable polysaccharide and protein based films containing active agents. Journal of Food Science, volume 76, Issue 3, R90-R102.

8. Pranoto, Y., Rakshit, S. K. and Salokhe, V. M., (2005). Enhancing antimicrobial activity of chitosan films by incorporating garlic oil, potassium sorbate and nisin. Lebensmittel-Wissenschaft und Technologie. 38: 859-865.

• Structure design of the polymer film to enable controlled release.

• Mechanical properties of the film: tensile strength.

• Concentration of antimicrobials in the polymer films, the antimicrobial may change the mechanical and optical properties.

• The effect of film thickness on activity, the diffusion rate is dependent on the thickness of the film.warning.png"• Structure design of the polymer film to enable controlled release.

• Mechanical properties of the film: tensile strength.

• Concentration of antimicrobials in the polymer films, the antimicrobial may change the mechanical and optical properties.

• The effect of film thickness on activity, the diffusion rate is dependent on the thickness of the film." cannot be used as a page name in this wiki. not applicable 2.2.5, 2.2.2 physical, biological stabilizing, packaging nanotechnology, other ScienceDirect packaging AND antimicrobials, active packaging AND antimicrobial WikiSysop :Template:Review document :Template:Review status



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Created by Evelina on 18 October 2011, at 13:10