Residual Solvents from Food Packaging

By: Pat Myers, AnalytiX Volume 7 Article 3

Two new Supelco standards contain twenty-five solvents of interest for food safety and regulation

Senior R&D Chemist, Supelco … 

Impact of packaging materials on food safety and sensory quality

Establishing, regulating and monitoring food safety are among the most important applications of analytical chemistry and chromatography. Food analysis covers myriad subjects, including compositional analysis for nutritional labeling and monitoring adulteration, contamination and compliance with regulations, among others. Foodstuffs can become contaminated from a variety of sources from the raw materials and at any point along the production process, including from the packaging materials.

Almost all foodstuffs consumed today are supplied encased in some form of packaging. By forming a barrier between the food and the environment, packaging materials maintain product quality and safety during shipping and storage. Packaging also protects the food from other packaging materials that may have desirable physical properties but are notorious sources of contamination, like recycled paperboard1. The types of packaging range from a simple, thin coating of foodgrade wax to complex multi-layered systems that combine paper, plastic and metallic components with adhesives.

However important the packaging is to maintaining the food quality and shelf-life, packaging materials are also a well-known source of contamination when they leach undesirable compounds into the food they are intended to protect. These compounds can be toxins and pose significant health hazards. They can also be sources of off-flavors or off-odors, diminishing the sensory quality of the product, which is a very important commercial aspect of food science2, 3.

The etiology of the contamination reveals that the manufacturing process used to make the package materials, adhesives that hold multi-layer packaging together, and the varnishes, inks and dyes applied to the finished package can all be sources of leachables or extractables that end up in the food. Solvents derived from these sources are a major contamination class and are of primary concern to food analysts.

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Current regulations

To ensure consumer safety and customer satisfaction, the United States and the European Union have implemented regulations to address the use of inks and dyes in food packaging and measure residual solvents4, 5. The US FDA regulates residual solvents in food packaging as indirect food additives under 21 C.F.R. §175.300. Residual solvents are subject to the global 50 ppm migration limit that applies to non-volatile food additives as well. EU standards EN 13628-1 and EN 13638-2 set forth test methods for the determination of residual solvents in flexible packaging. These standards monitor compliance with the EU Directive 89/109/EEC that applies to all food-contact substances. The directive states that food-contact substances must be manufactured in accordance with good manufacturing practices and must not adulterate the food.

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Analytical challenge

Besides establishing the barrier properties of new, innovative packaging with current food products and the use of existing packaging materials for new food products, food manufacturers and processors must also ensure they are in compliance with the above-mentioned regulations. Equally important is the adoption of an ongoing in-house quality control program to monitor approved packaging for unexpected changes in barrier properties that could result in undesirable levels of residual solvent contamination. Monitoring for residual solvents from packaging materials is typically performed using headspace sampling with GC/FID or GC/MS6. SPME followed by GC or GC/MS has also been employed7.

One challenge faced by analysts testing for residual solvents is the commercial availability of reliable reference standards. Without a commercial source, preparation of the standards is a time-consuming process in already over-stretched analytical laboratories.

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Sigma-Aldrich solution

Answering the need for reliable standards, Sigma- Aldrich developed two Supelco-brand residual solvent standard mixes. The two mixes represent the majority of solvents found in the inks and dyes used for food packaging graphics and are not on the Generally Recognized as Safe (GRAS) listing (see Table 2). All solvents in the mixes are first screened for identity and purity. The mixtures are then gravimetrically prepared and quantitatively analyzed by GC-MS (see Figure 1). A Certificate of Analysis accompanies each standard.

 

Figure 1 ......... GC Analysis of Residual Solvent Mixes for Packaging Standards

 

GC Conditions: column: VOCOL, 60 m x 0.25 mm I.D., 1.5 μm df (24154); oven: 35 °C (4 min.), 4 °C/min. to 200 °C (0 min.); inj.: 200 °C; det.: MSD, 280 °C; carrier gas: helium, 30 cm/sec.; vent flow: 140 mL/min.; injection: 0.5 μL

Residual Solvent Mixtures

Cat. No. Brand Description Package Size
48994-U Supelco Residual Solvents in Packaging Material Mix 1

14-component mixture containing equal volumes (each component 7.14% v/v) of the following:

1-Butanol, 2-Butanol, 2-Butanone, Butyl acetate, Cyclohexane, Cyclohexanone, Ethanol, 2-Ethoxy-ethanol, Ethyl acetate, Isobutyl acetate, Methanol, Methyl acetate, 2-Methoxyethyl acetate, Toluene
1 mL ampul
48995-U Supelco Residual Solvents in Packaging Material Mix 2

11-component mixture containing equal volumes (each component 9.09% v/v) of the following:

2-Ethoxyethyl acetate, Isopropyl acetate, Propyl acetate, 2-Methoxyethanol, 1-Methoxy-2-propanol, 4-Methyl-2-pentanone, 2-Methyl-1-propanol, Acetone, 1-Propanol, 2-Propanol, Tetrahydrofuran
1 mL ampul
 
Table 1........ Product Listing

 

Other analytical supplies

Cat. No. Brand Description
24154 Supelco VOCOL capillary GC column, 60 m x 0.25 mm I.D., 1.5 μm df

 

Mix 1: 14 components
(48994-U)

Mix 2: 11 components
(48995-U)
1-Butanol 2-Ethoxyethyl acetate
2-Butanol Isopropyl acetate
2-Butanone Propyl acetate
Butyl acetate 2-Methoxyethanol
Cyclohexane 1-Methoxy-2-propanol
Cyclohexanone 4-Methyl-2-pentanone
Ethanol 2-Methyl-1-propanol
2-Ethoxyethanol Acetone
Ethyl acetate 1-Propanol
Isobutyl acetate 2-Propanol
Methyl acetate
2-Methoxyethyl acetate
Toluene
 
Table 2....... Composition of Supelco Mixes for Residual Solvent Analysis in Packaging Materials

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Define your custom solvent and other ingredient mixtures

Each packaging material has its unique palette of possible contaminants, and new packaging materials are continually being researched and developed. We are happy to work with analysts in food and packaging industries to develop customized standards that contain components of specific interest. To see our complete list of standards and discuss our custom standard services

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Materials

     

References

  1. Song, Y. S.; Begley, T.; Paquette, K.; Komolprasert, V. Effectiveness of polypropylene film as a barrier to migration from recycled paperboard packaging to fatty and high-moisture food. Food Additives and Contaminants 2003, 20(9), 875 – 883.
  2. Bravo, A.; Hotchkiss, J. H.; Acree, T. E. Identification of Odor- Active Compounds Resulting from Thermal Oxidation of Polyethylene. J. Agric. Food Chem. 1992, 40, 1881 – 1885.
  3. Halek, G. W.; Levinson, J. J. Partitioning Behavior and Off-Flavor Thresholds in Cookies from Plastic Packaging Film Printing Ink Compounds. J. Food Science 1988, 53(6), 1806 – 1808.
  4. Keller and Heckman LLP. http://www.packaginglaw.com/ index_mf.cfm?id=101 (accessed May 3, 2007).
  5. Preparation of Food Contact Notifications and Food Additive Petitions for Food Contact Substances: Chemistry Recommendations, Final Guidance. http://www.cfsan.fda. gov/~dms/opa2pmnc.html (accessed May 3, 2007).
  6. Detection of Packaging Emissions using a Flexible Headspace Sampler Combined with a Multi Sensor System and a Separation Unit. http://www.gerstel.com/p-gc-an-2005-07.pdf (accessed May 3, 2007).
  7. Kusch, R.; Knupp, G. Headspace-SPME-GC-MS Identification of Volatile Organic Compounds Released from Expanded Polystyrene. J. Polymers and the Environment, 2004, 12(2), 83 – 87.

 

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