Food simulants migration testing

The finished rubber product will have to meet a specification in which a number of properties (e.g. hardness, tensile strength and elongation) are given target values. A number of other properties can be assessed, and these will depend upon the type of rubber and the application that it is going to be used in. An important example is the overall migration limit test, with the food simulant and test conditions (temperature and time) being dictated by the end use conditions. 

Brede et al. tested 50 flexible multilayer materials from 13 different manufacturers or suppliers using water as a food simulant, and test conditions close to their intended use. Twenty-two of these materials, from ten manufacturers or suppliers, were found to release detectable PAA using a colourimetric procedure (detection limit was 0.3 p,g/l, methylene dianiline [MDA] equivalents). The highest PAA migration was 15 pg/1 (MDA equivalents). 

The migration of package ingredients directly into a food product is often difficult to analyze instrumentally because of interference from food ingredients. Some of these analyses have been made, but it is generally preferable to use food simulating solvents listed in FDA regulations and to carry out extraction tests under the conditions described. 

The Scientific Committee for Food (SCF) lays down for toxicological evaluation of food contact substances three levels of toxicological tests dependent on the amount of migration (mg/kg food simulant) Level 1 < 0.05 level 2 0.05-5 level 3 >5. 

The migration/sorption behavior test for BHT and a-tocopherol in LDPE packaging materials in contact with fatty food simulants has indicated that the rate of migration of a-tocopherol into food simulants is lower than that for BHT. Since a-tocopherol was transferred from the film to the simulant to a lesser extent, it is considered a more stable antioxidant than BHT (Wessling et ah, 1998). BHT has also been found to migrate more rapidly than Irganox 1010 into dry food stored in LDPE wraps (Schwope et ah, 1987a). 

The European Commission has mandated the European Committee for Standardization to establish a validated method of analysis for the determination of OMLs and SMLs. If a product complies with the compositional requirements of the directives, i.e., it is produced from authorized monomers and additives, then it may be tested for any desired application. If it meets the migration requirements, it is acceptable for use in cases covered by that test method. Typical food simulants used in the tests are hot water, acetic acid, ethyl alcohol and olive oil. The choice of an appropriate simulant depends on the type of food expected to come into contact with the packaging. 

Because foodstuffs themselves are difficult to analyse and have a variable composition, testing packaging materials for migration almost invariably uses model foods, known as food simulants , which are designed to mimic the main classes of foodstuffs. There are some minor differences in detail between EU and US-FDA requirements but the essential elements are listed in Table 9.3. 

The term migration testing is almost universally associated with tests using food simulants (model foods) rather than testing for migration into foods. 

Baner, A.. Franz, R., Piringer, 0.1994. Alternative Fatty Food Simulants for Polymer Migration Testing . Chapter 2 in Food Packaging and Preservation. (M. Mathlouthi, ed.). Blackie Academic and Professional, London, presented at IFTEC symposium, 15-18 November 1992, The Hague, Netherlands. 

The whole area of specific migration determinations can be subdivided in two phases (i) the pre-analytical migration exposure phase, which is more or less identical to that necessary for overall migration determination and (ii) the pure analytical phase, where the specific migrant must be determined in the respective food or simulant as precisely and reproducibly as possible. This pure analytical migration test phase comprises many considerations to be made and includes so many technical possibilities that it deserves to be described in an own comprehensive section (see Section 10.2). 

An important conclusion from these findings was that even though this analytical method works in principle with olive oil as a food simulant, the migration test using olive oil or another fat simulant can provide false-negative results. Therefore, the method should only be applied in the case of short exposure periods with olive oil. If the method is carried out with olive oil, a recovery check with spiked olive oil applying the same time/temperature migration test conditions is necessary. In the case that such a recovery check indicates loss" of HMDA and/or EDA, then alternatively 95 % ethanol or iso-octane should be used as substitute fatty food simulants. 

FID) under the same analytical circumstances and in the same test run (same sample preparation etc.) as the migration solution (of the same food simulant) and the blank solution. One must be made certain that all other analytical parameters are kept constant in the different sample solutions and the only variable is the analyte concentration. In the case that an analyte peak in the migration solution is significantly smaller than that of the calibration point, this would demonstrate compliance... 

Philo M R, Jickells S M, Damant A P and Castle L, 1994, Stability of plastics monomers in food-simulating liquids under European Union migration test conditions. J. Agric. Food. Chem. 42,1497-1501. 

Philo M R, Damant A P and Castle L, 1997, Reactions of epoxide monomers in food simulants used to test plastics for migration. Food Additiv. Contam. 14 (1), 75-82. 

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