Food Packaging Migration Quiz

Migration and Food-Package Interactions

• Interactions between food and packaging materials can be physical, chemical, or biological.
• Physical interactions include the movement of chemical compounds across the food-package interface.
• Chemical interactions can involve corrosion of metal containers from contact with food products.
• Biological interactions can cause food spoilage due to contamination from the package.
• Concerns arise from harmful chemicals migrating from the packaging to the food, or vice-versa.
• Macroscopic scale migration involves movement of large fragments during food processing.
• Submicroscopic scale migration happens via molecular diffusion.
• Migration from packaging to food, often involving submicroscopic chemical compounds, is controlled by molecular diffusion.
• Migration from plastics is of particular concern in relation to consumer safety and regulations.
• "Scalping" refers to the migration of chemical compounds from food to package (reverse migration).
• Flavor scalping is an example, where desirable flavors in food transfer to packaging.
• Food contamination can occur from harmful components in packaging materials like metal, glass, or ceramic, that leads to corrosion. -Desirable and intentional migration of active compounds like antimicrobials or antioxidants are also included.

Migration Process & Potential Migrants

• Potential migrants in plastics, intended for food contact, include additives (e.g., esters, organic salts, amines).
• Additives are small molecules compared to the food matrix, with high mobility in plastics due to their different chemical nature.
• Residuals from the production process, such as monomers, catalysts, solvents, and adhesives, also migrate from packaging to food. -They also have a different chemical nature from the packaging materials and thus high mobility.
• New molecules formed during processing or aging can also migrate. -Ex. acetaldehyde & oligomers in PET.

Non-migrating System

• Negligible migration for high molecular weight polymers, some inorganic residues, or pigments is common.
• Zero assumption on migration may change depending on analytical techniques or regulatory specifications.
• Migration testing does not require direct food-packaging contact but applies to dry solids with limited direct contact.
• Migration to food is limited to volatile compounds with high vapor pressure at room temperature.
• Migration controlled via diffusion in material packaging, not by food characteristics.

Steps for Migration in Case of Poor Food-Package Contact

• Migration diffusion of migrant in package wall toward the food-package interface.
• Desorption of migrant at food-package interface.
• Adsorption of migrant onto food.

Leaching System and Mechanisms

• Requires direct contact between packaging and moist solid/liquid foods
• Mechanism a & b are involved in leaching: -Migrant has high diffusion coefficient in plastic, which easily dissolves into the contacting food. -Migrant has low diffusion in plastic initially, but increases its diffusion coefficient after liquid food component adsorption and diffusion into the package material -- causes swelling from interaction with the solvent.

Migration in the Case of Good Food-Package Contact

• Diffusion of migrant in package wall toward food-package interface.
• Concurrent solvent/food ingredient penetration changes package wall structure, increasing migrant mobility.
• Dissolution of migrant at food-package interface.
• Depends on migrant affinity to the package and food phases.
• Dispersion/diffusion of migrant into food.
• Migrant disperses into liquid foods or diffuses into solid food.

Migration Process Factors

• Diffusional mobility of potential migrants depends on: temperature, time, molecular mass, and chemical affinity with plastic.
• Migration occurs slowly, requiring several days for migrants to pass a few micrometers of plastic.
• Fick's First Law and factors related to it (e.g., diffusion flux, diffusivity, migrant concentration, distance).
• Migration is related to the characteristics of the migrant, food, and contact conditions.
  • Volatility & ability of the food component to dissolve the migrant will affect migration.
• Agitation & turbulence during transport promote migration.

Migration Issues in Food Packaging

• The type of food material, contact time, and temperature affect migration extensively.
• Substances migrating from packaging to food can be harmful.
• Even if migration is not harmful, it may affect flavor, taste, or acceptability.
• Preventing food contamination from packaging materials is paramount for food protection.

Chemicals from Plastics

• Plastics, due to their heterogeneity and manufacturing processes, are prone to migration.
• Migration can be linked to additives, residual components from production, and newly formed substances in the plastic.
• Examples of concern include VCM from PVC (a potential carcinogen), plasticizers (e.g., phthalates, increasing flexibility), primary aromatic amines (PAA) and others.

Recycled Plastics

• Post-consumer recycled (PCR) plastics may contain contaminants from their previous use, contact with other waste, or recycling techniques.
• Effective barriers (not absolute) should be used to prevent chemicals from recycled plastics, paper, and printing inks from migrating into the food.
  • Functional barriers (FBs) limit migration of permitted substances and reduce non-permitted amounts to below acceptable levels (e.g., 10 parts per billion in Europe).

Functional Barriers

• Only metals, glass, and PET are currently approved as functional barriers by the EU.
• Functional barriers are used to prevent migration of chemicals, such as those found in recycled materials, paper, and inks, from contaminating food products.

Microwave Susceptor

• Multi-layer structures (part of the packaging or a baking-pan) used to heat food (e.g., with microwave E).
• Aluminum, laminated to paper, boards, or plastic films (e.g., PET, OPP), are examples of materials in this application.
• Elevated temperatures (e.g., up to 200°C in < 1 minute) can promote diffusion and deterioration of the plastic, leading possible migration of adhesive compounds to the food.

Paper & Board

• Potential contamination issue; paper sacks contain chlorophenols, producing chloranisoles that can taint food.

Flavor Scalping & Sorption

• Migration of flavor compounds by the ability of plastic polymers to dissolve many low-molecular-weight substances.
• Sorption is mainly at the material's surface, with penetrations of varying depth and mechanisms (sorption or absorption).
• Effects are usually undesirable as they reduce or alter flavor.
• Effects of sorption affect both the product and container (e.g., vitamins loss, alteration in taste/flavor/color, decrease in antioxidant properties, shortened shelf life).
• Sorption affects the package (e.g., increase in gas/aroma permeability, decrease in mechanical properties leading to cracks and reduced adhesion, decreased seal strength).

Sensory Tainting

• Any material contacted with food must not taint with undesirable tastes or smells.
• Taint is a distinct taste/odor foreign to the food itself and is different from off-flavors.
• Tainting can come from compounds in inks, adhesives, coatings, varnishes, or other materials directly or indirectly contacting food.

Regulations

• Packaging materials need to be safe, ensuring inertness, meaning no migration of unwanted constituents into the food.
• Positive lists contain approved components with specific concentration limits and exclusions.
• Negative lists prohibit specific materials to ensure safety based on toxicity or dangerousness.

Migration Testing and Food Simulants

• Two approaches: Migration testing (simulation) and Predictive migration (mathematical modeling).
• Migration testing involves exposing packaging or samples to food simulants under controlled conditions to simulate food interactions and identify migrated compounds, quantify them, and determine their stability.
• Food simulants are substances whose composition and characteristics closely mimic the characteristics of food, making testing easier and more reliable.
• Simulants include: aqueous solutions (distilled water, acids), alcoholic mixtures, fatty compounds (oils), solids (e.g., adsorbent polymers), and solvents (e.g., heptane, iso-octane).

Migration Testing – Analytical Techniques

• Gravimetric tests determine the overall migration amount of solid substances that migrate.
• Various techniques can be used, including optical density measurements, titration (e.g., KMnO4), and modern or advanced techniques (e.g., FT-IR, GC-MS, LC-MS).
• These modern techniques determine specific migration.

Regulations

• Overall migration limits (OMLs) are limits on the amount (ppm or mg/dm2) of leaking/migrating components from packaging to food product, but values vary between countries.
• Specific migration limit (SML) is a limit on the amount of a specific substance moving from the package to the food.
• Maximum quantity (QM) limit is the maximum permitted concentration of specific substances in the final product.

Test your knowledge on the migration of substances in food packaging. This quiz covers key concepts such as chemical migration, consumer protection, and interactions between food and packaging materials. Understand the implications of these migrations for food safety and quality.