background image
Design of safe packaging materials under uncertainty
Olivier Vitrac
and Murielle Hayert

(1) INRA ­ UMR 614, Moulin de la Housse, BP 1039, F-51687 Reims cedex 2, FRANCE
(2) ENITIAA ­ UMR CNRS 6144, La Géraudière, F-44322 Nantes cedex 3, FRANCE
1 Abstract
This research work aims at developing simulation methodologies, which help the design of
packaging materials by accounting for the possible contamination of the food product in contact
by packaging substances. The main originality in the presented approaches consists in
considering various possible sources of uncertainties related to i) insufficient scientific
knowledge in transport properties (diffusion and partition coefficients, interfacial mass transfer
coefficient), in their activation or in product reactions, ii) the confidentiality of manufacturing
processes (e.g. composition) and iii) from the final use (final geometry, storage time and
temperature). We present a practical treatment for the optimization under uncertainties (type of
molecules, initial concentration). To this extent, a progressive modeling based on a range of point
estimates (simplified rules) and on probabilistic modeling (sophisticated rules) is developed. The
results illustrate on typical cases (either monolayer or multilayer materials, known and poorly
known contaminants) the benefits of an iterative process of the quantification of uncertainty
effects. Simplified rules based on conservative assumptions generate the results required for a
rapid screening of critical points of the contamination of food products. Probabilistic modeling
based on continuous distributions is adapted to the dimensionless physical problem and used to
enable the assessor to give the decision-maker (client or provider) an increasingly clear picture of
the likelihood of acceptable thresholds (e.g. regulatory specific migration limit, toxicological
concern) being exceeded.
2 Introduction
During the twentieth century, the rise of plastic materials on the market was promoted by the
development of specific additives: antioxidants, plasticizers, dyes, etc. and other substances with
technological interest: catalysts, chock agent, antistatic agents, etc. Currently, more than 70% of
processed food is in contact with plastic materials in northern countries (Han, 2005). For food
applications, the substances present in the packaging material are both the intentionally added
substances during the different formulation stages (prior polymerization, processing, assembling,
printing ...) and the possible residues: polymerization residues, degradation products. All these
substances are not covalently bounded to the polymer matrix and can be desorbed into food.

As acknowledged during the World Summit on sustainable development in Johannesburg in
2002, consumer and environment protection have drawn more and more the attention of public
and authorities. In EU, the recent directive proposal named "Registration, Evaluation
Authorization and Restriction of Chemicals" (REACH) enforces that the introduction of a new