Migration of Photoinitiators in Food Packaging: A Review

Photoinitiators are highly photoactive compounds included in the formulations of UV curing printing inks and varnishes. Twenty five of those photoinitiators can be found in the bibliography regarding food packaging migration and analytical methods with an increasing interest in the last 9 years because of the foodstuffs contamination with 2-isopropylthioxanthone detected in 2005. An overview about migration of photoinitiators in food packaging is firstly given in terms of Rapid Alert System for Food and Feed notifications, mechanisms of migration, and specific migration limits. Besides set off, a migration model based on diffusion and partition coefficients is considered to analyse the factors affecting migration: physicochemical properties of the photoinitiator, characteristics of the foodstuffs and food simulants, temperature and packaging. Molecular weight, volatility, polarity and lipophilicity are considered as the main physicochemical properties of the photoinitiators playing a role in migration. In relation with the food packaging, information from published works is reviewed, taking into account the special migration behaviour of paper and cartonboard as well as the efficiency of different plastic films as barriers to avoid or reduce migration. Results of the application of the migration model are compared with reported data from the bibliography. Finally, the use of polymeric multifunctional photoinitiators is concluded as the best option for ultraviolet curing inks and varnishes to print food packaging. They have higher molecular weight together with fewer and lower volatility photodecomposition byproducts and a higher probability than conventional photoinitiators of being bound into the cured polymer matrix. Copyright (c) 2014 John Wiley & Sons, Ltd.