Sustainability in Packaging: Migration, Testing, and Regulation

I. Migration Phenomena and Food Packaging Risks

Definition: Chemical transfer from printed layers to packaged food due to molecular size (typically <1000 Da) and chemical properties.

High-Risk Packaging Types Requiring LM Inks:

II. Three-Dimensional Migration Mechanisms

Set-off Migration

Trigger: Direct contact between printed layer and food-contact surface under reel pressure (>0.1 MPa) or stack load (>50 kg/m²).

Process: Physical transfer of uncured monomers/photoinitiators under pressure (Image 1).

Image 1,Set-off migration can occur between a surface printed layer to a non-printed food contact surface when in close contact due to the pressure existing in the reel or stack

Diffusion Migration

Two-stage Path:

Stage 1: Pre-filling period; small molecules (MW<500 Da) penetrate substrate inward.

Stage 2: Post-filling; lipophilic substances (e.g., mineral oils) extracted by food (Image 2).

Image 2,Diffusion migration can occur due to the ease with which small and mobile molecules can penetrate across packaging material layers.

Gas Phase Migration

Typical Migrants: Mineral oils (MOSH/MOAH), semi-volatile UV photoinitiators (e.g., BP, ITX).

Unique Path: Volatilization from substrate → adsorption onto food via headspace (Image 3).

Image 3,Migrants,such as mineral oils or some UV photoinitiators,can migrate from the substrate via the gas phase.

III. Core Design Principles of Low Migration (LM) Ink Systems

Molecular Weight Threshold Principle:

Empirical rule: Components with MW > 1000 Da exhibit negligible migration (diffusion coefficient ∝ 1/√MW).

LM Formulation Components:

High-MW photoinitiators (e.g., acylphosphine oxides, MW 800-1200 Da)

Oligomers (acrylate-based, MW 1500-5000 Da)

Monomers (high-functionality to reduce residues)

Vs. Standard Inks: Standard inks contain low-MW substances (200-500 Da) with high migration risk (Image 4).

Image 4,Formulation components of low-migration inks

IV. Global Food Contact Material Regulations 

Europe/Middle East/Africa (EMEA)

Swiss Ordinance (817.023.21)

World’s first positive list for printing inks:

List A: Toxicologically assessed substances (SMLs/OMLs, e.g., aniline SML=0.01 ppm)

List B: Non-assessed substances (detection limit ≤10 ppb)

Scope: Intentionally Added Substances (IAS) & non-direct food contact (non-DFC) inks only

German Ink Ordinance (21st Consumer Goods Amendment)

Transition period: Full implementation by January 1, 2026

Rules for unlisted substances:

Prohibited for DFC applications

Non-CMR (carcinogenic/mutagenic/reprotoxic) classification required

Migration must be <10 ppb

Non-Intentionally Added Substances (NIAS): Self-assessment per international scientific principles (e.g., EFSA guidelines)

Key Americas & Asia Regulations

V. Comprehensive Migration Testing Protocol

1. Test Basis & Simulant Selection 

Regulatory reference: (EU) No 10/2011 Annex III

Food simulant matrix:

2. Worst-Case Scenario Sampling Strategy

Critical parameter coverage:

Sample handling protocol:

Industrial storage simulation: Stack pressure ≥100 kg/m², 40±2°C, 60% RH

Transport protection: Aluminum foil wrapping (prevent contaminant adsorption)

Traceability: Sample ID linked to ink batch/curing energy/storage duratio

3.Testing Methods (Images 8-9)

Image 8(above),9(below),Printed samples cam be exposed to simulant using a standard cell or directly filled in the packaging.

Direct filling: For sealed containers (e.g., PEHD bottle sleeves, PES cups)

Steps: Simulant injection → sealing → incubation → HPLC/GC-MS analysis

Standard cell exposure: For flat materials (e.g., labels)

Equipment: EU migration cell (1-2 dm² area)

Conditions: Simulant contact with single printed layer (60±5 μm thickness)

4. Data Conversion & Compliance Thresholds

Unit conversion formula:

• Migration(μg/kg)=Detected value(μg/dm2)×6 dm21 kg foodMigration(μg/kg)=Detected value(μg/dm2)×1kgfood6dm2​

Compliance limits:

OML: ≤60 mg/kg

SML: e.g., BPA ≤0.6 mg/kg

Unlisted substances: ≤10 ppb (0.01 mg/kg)

5. Industry Guidance Supplement

EuPIA Migration Test Guidance (www.eupia.org) key recommendations:

NIAS screening: GC×GC-TOFMS non-targeted analysis

Photoinitiator degradation products: Mandatory assessment (e.g., benzophenone photolysis products)

Reference:

Brown, C. (2023). Sustainability in Packaging: Migration, Testing and Regulation. UV+EB Technology, Q4 2023, 42-45.

Regulatory Sources:

(EU) No 10/2011: https://eur-lex.europa.eu

Swiss Ordinance 817.023.21: https://www.admin.ch

German Ink Ordinance: https://www.bvl.bund.de