Packaging Concerns: Opening Up a Can of…Well You Know

Many of us know that the testing of food products for contaminants like pathogens, pesticides or heavy metals is an important part of ensuring the safety of our food supply. But what happens when the food is packaged? Can the materials used to contain a food product have an impact on safety? Can the packaging have an effect on the quality of the product – how it looks, smells, or tastes, and maybe most importantly, will chemical substances not readily detectable by our senses, migrate from the packaging to the food – and if so, how much of the chemical substances are migrating? Do the levels in the food product pose a health risk?

Fortunately, we have ways of answering these important questions and this falls under regulations related to Food Contact Substances. Many countries and collectives of countries have regulations pertaining to food contact substances. The two most commonly cited are those by the European Commission (EC) and the Food and Drug Administration (FDA). (1, 2) The regulations are detailed explanations of the chemical substances that are allowed to be used for the manufacture of articles for the purposes of eating and preparing foods (utensils and vessels) or used in containers designed to store food. We’ll take a closer look at the regulations a little later.

Migration: Not Just for the Birds

We are all familiar with the large variety of materials used for food packaging. Whether the container is metallic, plastic, or coated paper, there is the possibility that one or more chemical substances may leach from the packaging material. A simplified view of this is shown in Figure 1. Here a container is in direct contact with a food product. The mode of transport from the container is diffusion driven; the chemical substance is absent from the food product but is present in the container wall. Therefore a concentration gradient exists and diffusion occurs from a region of high concentration (container wall) to a region of low concentration (food product). 

Figure 1.A look at chemical migration to a food product.

Substances that can migrate may be monomers, oligomers, metals, catalysts, plasticizers, adjuvants, pigments, dyes, production aids (including mold release agents), and decomposition products. The types and amounts of substances that will migrate depending on the type of food product in contact with the container (acidic foods, alcohol-containing foods, fatty foods, etc.), length of time the food is in contact with the container, and the processing/storage temperature.  You may be familiar with drinking bottled water that has been in storage for too long a period of time and received first-hand experience with the “plastic” taste.

Is It Safe?: The Regulatory Marathon

As defined by the FDA, a food contact substance (FCS) is “any substance that is intended for use as a component of materials used in manufacturing, packing, packaging, transporting, or holding food if the use is not intended to have any technical effect in the food”. (3)  As mentioned earlier EC and FDA provide extensive guidance on the types and allowable limits of FCSs present in a food product. This guidance is based on the best available science at the time of publication and is updated periodically.

A petition process is used by the regulatory agency to evaluate the safety of the FCS. This formal process, known as a Food Contact Notification (FCN) by FDA, is a request for approval of the material. (4) It is a substantial collection of information about the FCS and is prepared by the petitioner – usually a manufacturer, supplier, or user of the packaging material - prior to going to market with a product.

Although the EC does not use the terms Food Contact Substance and Food Contact Notification, the scope and intention of the EC regulations are very similar to those of the FDA. A major part of the petition processes for both agencies is determining the amounts of food contact substances that migrate from the packaging material to food. This key data is crucial in evaluating safety and migration testing is a critical role played by the chemistry testing laboratory.

Putting it to the Test

Ensuring the safety of food packaging is the purpose of migration testing and as our understanding of toxicity increases, the concerns over packaging material additives likewise increases. Consider the compound classes that have gained much notice in the past few years, both used as additives in the manufacture of food containers and both are now under intense scrutiny by regulatory agencies: Bisphenol A and phthalates.

These compounds are known to migrate to food from containers but determining how much migrates for different food types, processing conditions, and storage conditions is done using procedures developed by regulatory agencies. The procedures go into explicit detail on how the testing is to be performed. Let’s consider a hypothetical situation of a manufacturer who wants to package tomato sauce in a plastic jar that is processed by pasteurization. Deciding how to do the testing goes something like this (FDA guidance referenced):

1. This jar is a single-use item (as opposed to a repeated-use item), it is not intended to be reused.
2. The actual food product is not used for the testing. Instead, simulants - a chemical substance or mixture of substances - are used. For example, to simulate an acidic food like tomato sauce, one uses a 10% ethanol or 3% acetic acid solution as the simulant.
3. The item is pasteurized and, based on the temperature conditions, the procedure states that the simulant should be added to the jar at 100^OC, held at this temperature for 30 minutes, and then allowed to cool to 40^OC and remain in the jar for 10 days.

Now that it has been established how the migration testing is to be done, the manufacturer enlists the services of a reputable chemistry testing laboratory. The lab, having a thorough understanding of the regulatory guidance, and having had one or more conversations with the manufacturer, will perform the migration testing under the conditions of use for the plastic jar. The lab may use specially-designed migration cells or “test rigs” to expose the plastic jar to the simulant and the lab will have the necessary ovens, baths or other high-temperature testing devices needed to meet the exposure temperatures and times required. Finally, the identities and amounts of compounds that migrated to the simulant will be determined using state-of-the-art testing instrumentation like Gas Chromatography Mass Spectrometry (GC-MS) or Liquid Chromatography Mass Spectrometry (LC-MS).

As an example of the type of data interpreted by the lab, Figure 2 shows GC-MS results for the determination of the plasticizer Tris (2-ethyhexyl) trimellitate (TOTM) from an extraction done on a plastic material. The top image is a chromatogram showing TOTM eluting last while the bottom image is the mass spectral data that permits unambiguous identification. Using this data the lab quantifies the amount of TOTM present in the extract. Upon receiving results from the lab, the manufacturer can complete the FCN submission to gain approval to mass market the product. 

Eurofins SF Analytical is renowned for successfully investigating the most challenging problems in food, beverages, and packaging; including food contact notification testing, foreign material identification, off-flavor/off-odor analysis, chemical ingredient verification (USP, NF, FCC, EP compendial methods), product recall support, insurance and legal investigations. 

Useful Reading:

1. europa.eu/food/safety/chemical_safety/food_contact_materials_en
2. gov/Food/IngredientsPackagingLabeling/PackagingFCS/default.htm
3. Guidance for Industry: Preparation of Premarket Submissions for Food Contact Substances: Chemistry Recommendations, fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/IngredientsAdditivesGRASPackaging/ucm081818.htm
4. foodsafetymagazine.com/magazine-archive1/octobernovember-2005/fdas-food-contact-substance-notification-program/

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