Silver migration from nanosilver and a commercially available zeolite filler polyethylene composites to food simulants

Abstract

Polyethylene composites containing Agion^TM commercial silver ion filler at three different percentage fill rates (0.5, 1.0 and 2% w/w) and polyethylene composites containing laboratory produced silver nanoparticles (Agnps) at two different percentage fill rates (0.1 and 0.5% w/w) underwent migration tests according to Commission Regulation (EU) No. 10/2011. Migrated silver in the two simulants (acidified water with 3% acetic acid and distilled water) was quantified using two techniques: inductively coupled atomic emission spectroscopy (ICPAES) and Hach Lange spectroscopy. The former had higher sensitivity with mean silver migration from Agion composites (n = 12) ranging from < 0.001 to 1.50 × 10⁻² mg l^–1. Mean silver migration from Agnps composites ranged from 4.65 × 10⁻² to 0.38 mg l^–1 and 8.92 × 10⁻² and 5.15 × 10⁻² mg l^–1 for Hach Lange spectrophotometry and ICPAES, respectively. Both percentage fill rate in the composite and the simulant type, as factors, were found to be significant in both silver migration from Agion (p < 0.0001 and < 0.01, respectively) and Agnps (p < 0.05 and < 0.01, respectively). Transmission electron microscopy (TEM) imagery showed differences in size distributions and morphology of particles (shape and degree of agglomeration) before and after migration. PE composites containing 0.5% Agion, simulating contact with non-acidic foods, was the only scenario that did not exceed the permitted migration level of non-authorised substances given in EU 10/2011. This study illustrates the need for careful engineering of the composite filler system to conform to limits with cognisance of food pH and percentage fill rate.

Keywords:

• nanoparticles
• silver
• food packaging
• antimicrobial; migration

Acknowledgements

The Authors would like to acknowledge and thank the UCD Conway Institute of Biomolecular and Biomedical Research for the use of their core technology facilities.

Funding

The authors acknowledge funding for this project by FIRM as administered by the Department of Agriculture, Food and the Marine.