Laboratory validation of the method for determination of overall migration in food packaging plastic materials

Packaging has become an integral part of the processing, preservation, distribution, marketing, and even the cooking of foods. Packaging materials provide protection for microbiological, chemical, and physical contamination. However, components of the packaging material must be safe to the product as well as to the consumers. Food may interact with the packaging materials and this may change the initial mechanical and barrier properties as well as the safety of the product. Migration is defined as the transfer of substances from the package to foodstuffs. The migration of potentially toxic substances from packaging material to foods is a major concern in the selection and use of materials for food packaging because of the possible effect upon human health. Since its introduction in the 1950’s, the use of plastic in the packaging industry has increased at a greater rate than any other packaging material due to their low cost and outstanding functional service properties (Hernandez and Giacin, 1998) (1). However plastic materials may be the most problematic, due the nature of the molecules of the materials. Migration can be classified as overall or specific migration. Overall migration corresponds to the total components, identified or not, that migrate from the packaging material. The present work aims the optimization and validation of the methodology to determine the overall migration from plastic materials to foodstuffs, aiming the accreditation according ISO/IEC 17025 (2). The chosen method consists in the total immersion of plastic materials intended to come in contact with foodstuffs into aqueous based food simulants. The selection of the simulating conditions, temperature and time of contact, as well as the food simulant(s), differs according to the intended application of the test specimens. This selection was made in agreement with National Legislation (3) and NP EN 1186(4). The overall migration from plastic samples was determined as the mass of non-volatile residue after evaporation of the food simulant following immersion. The validation of the analytical procedure consisted on the evaluation of the following parameters: limit of detection (LOD), limit of quantification (LOQ), repeatability (ri) and intermediate precision (Pi). LOD and LOQ were determined through the analyses of a series of blank samples. Repeatability (ri) and Intermediate Precision (Pi) were evaluated using real samples of different kinds of plastic with different levels of overall migration, according ISO 5725 (5). The uncertainty estimation, calculated for all kinds of plastic tested, was based on intralaboratory validation data. We concluded that the laboratory performance complies with the requirements of EN 1186 (4). With this method we can assure that the Food and Nutrition Department may submit this test to the Accreditation Body and assess these plastic materials according with the legislation, contributing for food safety and public health protection. Key words: Overall migration; Plastics, Foodstuffs, Food safety. References (1) Hernandez, R.J., Giacin, J.R., 1998. Factors affecting permeation, absorption and migration processes in packageproduct systems. In: Taub, I.A., Singh, R.P.(Eds.), Food Storage Stability. CRC Press, New York, pp. 269–330. (2) ISO/IEC 17025:2005 - General requirements for the competence of testing and calibration laboratories. (3) Decreto-Lei n.º 62/2008. D.R. n.º 63, Série I 31 de March 2008; Diretiva 82/711/CEE do Conselho 18 de October 1982; Diretiva 85/572/CEE do Conselho 19 December 1985. (4) NP EN 1186:2002 – Materials and articles in contact with foodstuffs – Plastics – Part 1: Guide to the selection of conditions and test methods for overall migration; NP EN 1186:2002 – Materials and articles in contact with foodstuffs – Plastics – Part 3: Test methods for overall migration into aqueous food stimulants by total immersion. (5) ISO 5725:1994 - Accuracy (trueness and precision) of measurement methods and results – Part 1: General principles and definitions; Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method; Part 3: Intermediate measures of precision of a standard measurement method; Part 6: Use in practice of accuracy values.