If you are a food manufacturer, you most likely incorporate quality control and inspection equipment all throughout your plant. Metal detection and X-ray inspection traditionally have been the first line of defense to identify the presence of foreign contaminants in food products before they have the chance to leave the processing plant. However, how about the packaging itself?
If your food is wrapped in a plastic, which usually consists of a polymer multi-layer film, you may want to ensure the film is doing its job before you pass your product on to consumers. In food packaging, polymer laminates are used not only to protect the food, but also to retain aroma and flavors, and to extend shelf life.
According to the USDA, because packaging touches the meat, it is considered an indirect additive because chemicals in packaging can migrate into the food. Any material intended for use in food packaging must be formulated in compliance with FDA requirements for its intended use. Here is an excerpt from the USDA site:
Meat and poultry products may not be packaged in a container composed of any substances that may adulterate the contents or be injurious to health. Packaging materials entering a meat or poultry plant must be accompanied or covered by a guaranty or statement of assurance from the packaging supplier. The guaranty must state that the material complies with the Federal Food, Drug and Cosmetic Act (FFDCA). It must also state the brand name, supplier, and conditions for use, including temperature and other limits….
Needless to say, strictly controlling the quality and composition of these films is important to the manufacturers of polymer film, the food processors, and to the customers who are walking down that grocery store aisle. The last thing a host wants to encounter on the morning of a holiday or special dinner is a spoiled turkey, fish, ham, or roast. And the last thing a food processor wants is to violate FDA regulations.
Because food processors adhere to strict quality control procedures, including analysis of the products used in the plant, plastics manufacturers must do the same. Polymer multi-layer films are made by co-extrusion and lamination techniques, which are polymer processing technologies capable of producing films with improved barrier and mechanical properties. But sometimes problems can occur during film manufacture. Multi-layer films can encounter problems like introduction of defect particles and separation of the layers.
Current analytical methods used to control the quality and composition of these films during and after production include Nuclear Magnetic Resonance (NMR) and differential scanning calorimetry (DSC). Many film manufacturers also rely on Raman spectroscopy to provide a means of analysis and quality control because Raman provides definitive molecular information. The technique is highly sensitive to small changes in molecular backbone and branching configurations and is thus ideal for polymer identification. Spectral differences can be exploited to estimate thickness of the constituent layers, while searching spectral libraries identify their composition. The technique is also ideal for identifying the source and identity of defects and inclusions in polymer films. (Read more in this article...Thanksgiving All Wrapped Up.)
Your brand and your bottom line counts on your company producing a quality product and keeping its good reputation. If you are dedicated to ensuring your customer gets the best quality product, you probably analyze the food when it comes in the door, and then inspect it all along the processing line to ensure there are no contaminants. Just don’t forget to make sure the plastic film that is wrapped around your food product lives up to your high standards.
Editor’s Note: If you want to learn more about Raman microscopy analysis of multi-layer polymer films, you can read the application note, which includes a detailed account of an experiment involving the analysis of the layers of a polymer multi-layer film, including the methodology, sample preparation directions, equipment used, spectra, and results.