Influence of solvent absorption on the migration of Irganox 1076 from LDPE

The effect of solvent absorption on additive migration was studied by relating the diffusion coefficient ( D ) of Irganox 1076 to the maximum solvent absorption of different solvents in low-density polyethylene (LDPE) film. Solvents tested were ethanol, isopropanol, isooctane, ethylacetate, cyclohexane, tributyrin, tricaprylin and olive oil. Diffusion and partition coefficients were determined by fitting the migration curves, i.e. the concentration of Irganox 1076 in solvent as a function of time, with Fick's diffusion equation. The results for the low molecular weight solvents show that with increasing maximum solvent absorption, D of Irganox 1076 is increasing as well. This trend is not observed for the two triglycerides and olive oil. In spite of absorption, no increase in D was observed. The obtained result is the basis of an extended predictive migration model that, besides migrant and polymer properties, is also based on the maximum solvent absorption in the polymer.     

Characterizing the migration of antioxidants from polypropylene into fatty food simulants

The migration (diffusion and equilibrium) processes of antioxidants (AOs) from polypropylene (PP) films of different thicknesses into n-heptane and 95% ethanol as fatty food simulants were analysed at 20, 37 and 60°C. Heptane fully extracted the AOs from the polymer while a partition equilibrium described the migration to ethanol. The kinetics of migration were also studied via the diffusion coefficients. As expected, diffusion was found to be faster when the polymer was in contact with heptane, due to polymer swelling by the solvent. The kinetics of the process in ethanol was described by different theoretical expressions which are discussed. Equations disregarding partition equilibrium failed to describe the process and the diffusion coefficient values obtained through them were much smaller than the actual ones and dependent on film thickness. The results also showed the significance of food simulant selection in the analysis of food-packaging interactions and migration variability with thickness.     

Modelling of simultaneous two-sided migration into water and olive oil from nylon food packaging

Nylon 6 and nylon 12 food packaging materials used as sausage casings are typically exposed to fatty food on one side and boiling water on the other during the cooking process. To simulate the migration behaviour under these conditions, a special migration cell was constructed and filled with olive oil on one side of the polymer and water on the other to find out what amounts of the migrants will transfer to either side and phase at 100 °C. Results show that when a nylon 6 film is exposed to the conditions as described above, total mass transfer of the monomer—caprolactam—into the water phase occurs after 2 h at 100 °C. Nylon 12 sausage casings release similar amounts of their monomer—laurolactam—into both the aqueous and oil phase. An existing computer migration model was adapted to simulate the situation of simultaneous two-sided migration applying previously determined diffusion and partitioning coefficients. The suitability of the model was confirmed by experimental data.     

Migration of additives from polymers into food simulants: numerical solution of a mathematical model taking into account food and polymer interactions

The principle of a computing program describing precisely the migration of additives from a polymer into a food simulant is presented. As six parameters are used to fit the simulant sorption and additive extraction kinetics, the parameters have been determined by independent experiments. Owing to the complicated coupling between the liquid and additive diffusion processes, migration kinetics cannot be obtained by a mathematical resolution of kinetic equations, but they must be calculated by numerical analysis. The method is applied to a UV absorber in polypropylene migrating into glyceryl tripelargonate, a pure triglyceride, of which behaviour and average molecular weight are similar to official fatty food simulants. Properly designed experiments validate the model used to fit the migration kinetics. The possibility of erasing any parameters is also discussed.     

Polymer additive migration to foods - a direct comparison of experimental data and values calculated from migration models for high density polyethylene (HDPE)

To reduce the amount of compliance testing for food contact polymers the use of migration modelling has been proposed. This study was conducted to provide valid data for the independent evaluation of two such diffusion-based models using a range of different high density polyethylene (HDPE) polymers and plastics additives. Seventy-two experimental migration data have been obtained in triplicate and used to evaluate two Fickian-based migration models in the prediction of specific migration of four HDPE additives into olive oil. All tests were conducted using olive oil, representing the most severe case for fatty foods with test conditions of 2h at 70oC, 6h at 70oC, 10 days at 40oC representing short term exposures at high temperatures and room temperature storage. Predicted migration values were calculated by inserting the measured initial concentration of additive in the polymers (Cp,0) into the equations together with known variables such as additive molecular weight, temperature and exposure time. The results indicate that both models predict migration values into olive oil close to, or in excess of, the experimental results. The Piringer migration model, using the 'exact' calculations of the Migratest Lite program, gave an overestimation for 83% of the migration values generated in this study. The highest overestimation was 3.7 times the measured value. For all measurements, the predicted migration from the Migratest Lite program was greater than 50% of the observed value. The FDA model was found more accurately to predict migration in most situations but underestimated migration more frequently. Differences in the polymer specification had little effect on specific migration of the additives investigated.     

Worst case prediction of additives migration from polystyrene for food safety purposes: a model update

A reliable prediction of migration levels of plastic additives into food requires a robust estimation of diffusivity. Predictive modelling of diffusivity as recommended by the EU commission is carried out using a semi-empirical equation that relies on two polymer-dependent parameters. These parameters were determined for the polymers most used by packaging industry (LLDPE, HDPE, PP, PET, PS, HIPS) from the diffusivity data available at that time. In the specific case of general purpose polystyrene, the diffusivity data published since then shows that the use of the equation with the original parameters results in systematic underestimation of diffusivity. The goal of this study was therefore, to propose an update of the aforementioned parameters for PS on the basis of up to date diffusivity data, so the equation can be used for a reasoned overestimation of diffusivity.     

Release of bisphenol A from polycarbonate baby bottles: mechanisms of formation and investigation of worst case scenarios

The question was further investigated whether there could be conditions resulting in contamination of beverages in polycarbonate bottles for babies with bisphenol A (BPA) at concentrations causing the tolerable daily intake (TDI) to be approached or exceeded. It is a follow up of previous work showing increased release of BPA after extended use of the bottles. Migration in the proper sense was low, but larger amounts of BPA were observed from degradation of the polycarbonate. Since there are no standardized testing conditions to determine release by degradation of the polymer, worst case scenarios were investigated. Alkali washing solutions at concentrations typical for dishwashers contained BPA in concentrations little above 100 μg/l. In reality they are diluted in the general washing liquid and finally poured out. Drying was the most critical step, particularly after inadequate rinsing of bottles, when alkali detergent was “baked” to the bottle wall at elevated temperature. BPA thus formed is transferred into the beverage, but is unlikely to exceed 10 μg/l. The highest transfer into the beverage (up to about 500 μg/l) could occur when the bottle is positioned in the dishwasher at such inclination that the detergent solution does not fully run off and is poorly rinsed, but this scenario is unlikely to often occur. In conclusion, even rather extreme scenarios do not result in BPA contamination near to the level corresponding to the TDI.     

Di(2-ethylhexyl) adipate migration from PVC-cling film into packaged sea bream (Sparus aurata) and rainbow trout (Oncorhynchus mykiss) fillets: kinetic study and control of compliance with EU specifications

Polyvinyl chloride (PVC) film containing di(2-ethylhexyl) adipate (DEHA) plasticizer was used to wrap sea bream (Sparus aurata) and rainbow trout (Oncorhynchus mykiss) fillet samples with and without skin. After wrapping the samples were stored at 2 ± 0.5 °C and analyzed for DEHA content at time intervals between 5 and 360 h of contact (kinetic study). Determination of DEHA was performed using a direct gas chromatography (GC) method. Statistically significant differences (p < 0.05) in migration of DEHA were observed between the two fish fillet samples: the mean equilibrium migration amount of DEHA in sea bream was 2.93 mg/dm² film (91.9 mg/kg fillet) corresponding to a loss of 19.0% (w/w) DEHA from PVC film; while the mean equilibrium amount of DEHA in rainbow trout was 3.74 mg/dm² (117.6 mg/kg) corresponding to a loss of 23.9% (w/w) DEHA. The above values for DEHA in sea bream are very close to the limit of 3 mg/dm² of film surface set by the EU for DEHA while the corresponding migration values for rainbow trout exceeded this limit. Diffusion coefficients for DEHA in the PVC film during contact with both fish fillets were calculated and found significantly different between two fish samples. Furthermore, the presence of skin on the fillet decreased migration of DEHA into the fish flesh by a factor of 2.4–2.8. Based on equilibrium migration values of DEHA it is concluded that for a 60-kg adult, a daily consumption of 150 g rainbow trout or 200 g sea bream fillet packaged in PVC film would result in a daily intake of DEHA close to the tolerable daily intake (TDI) of 0.3 mg/kg body weight set by the EU.     

Evaluating the migration of ingredients from active packaging and development of dedicated methods: a study of two iron-based oxygen absorbers

The behaviour of two commercial oxygen-scavenging products with respect to migration of active ingredients into foodstuffs was investigated. Migrants were identified, and by using appropriate analytical methods, migration was determined in a variety of liquid, solid or gelled food simulants and foods. Simulants were chosen to cover a range of water activities and viscosities. Foods and the gelled food simulant agar were packed with and without vacuum, and with the oxygen scavenger in various locations relative to the packed food. The main migrants, as identified by X-ray fluorescence spectrometry, infrared spectroscopy and scanning electron microscopy with energy-dispersive spectrometry were Na + and Cl - in non-acidic aqueous simulants, and Na + , Cl - and Fe 2+ in 3% acetic acid. Migration into aqueous simulants exceeded the current European Union limit for total migration from plastic materials (assumed to be currently applicable to these systems) and was probably excessive by any reasonable standard. However, neither oxygen scavenger appeared to release significant quantities of migrants into solid foods when the scavenger was properly located in the package and the packing process does not favour the contents becoming wet by water released from the food.     

Tailoring fatty food simulants made from solvent mixtures (2): determining the equivalent migration behaviour of olive oil and of solvents in the case of polyolefins

It is suggested that solvent mixtures consisting of an ester and of an inert solvent can be used as fatty food simulants capable of having the same migration behaviour as olive oil with plastics. Migration tests carried out with low-density polyethylene for 20 and 48h in an 8 and 5% mixture of tert-butyl acetate in ethanol respectively gave results equivalent to those obtained with olive oil after 10 days at 40°C. The use of solvent mixtures facilitated the analysis and improved detection limits, giving good repeatability. Furthermore, the more rapid migration in solvent mixtures can be particularly useful for industrial controls as alternative test methods.     

Six open questions about the migration of engineered nano-objects from polymer-based food-contact materials: a review

ABSTRACT

The use of nanomaterials in food-contact applications has created enormous interest in recent years. The potential migration of engineered nano-objects (ENOs) from food-contact materials (FCMs) is one of the most important concerns regarding potential human exposure to ENOs and health risks. Current research focusing on FCMs has often reached inconsistency regarding migration of ENOs. The scope of this critical review is to give a concise overview of the most relevant aspects of the subject, and to identify and discuss the major open questions in relation to migration of ENOs from FCMs. This includes the very fundamental questions whether ENOs can migrate from FCMs at all and what the potential release mechanisms of ENOs could be. The inconsistency of findings from experimental studies is highlighted based on the example of silver nanoparticle migration from polymer-based FCMs. Challenges in the detection and characterisation of ENOs in migration studies and the suitability of the most frequently used analytical techniques are discussed. Further, this review questions the suitability of standard food simulants and migration test conditions for FCMs as well as of conventional mathematical migration models. Considerations regarding the risk for consumers associated with migrating ENOs from FCMs are discussed.     

The migration from the internal coatings of food cans; summary of the findings and call for more effective regulation of polymers in contact with foods: a review

The analysis of migrates from the internal coatings of food cans showed that the present regulation is not sufficient to ensure safety of food contact polymers. The migrates often consist of complex mixtures of reaction products and impurities, and their harmlessness cannot be deduced from the use of non-toxic starting substances compiled in positive lists. The regulation proposed herein asks producers to analyse the composition of the migrates. It includes an upper limit for the molecular weight (e.g. 1000Da) and thresholds defining concentrations in the foods down to which components must be identified and evaluated. Primarily considering feasibility at reasonable costs, thresholds of 30 mu g/kg for individual components and 300 mu g/kg for the sum of the unidentified materials are proposed. Producers must be able to demonstrate that the individual components or mixtures exceeding this limit, including reaction products with food components, have no toxic effect.     

Characterisation and migration properties of silicone materials during typical long-term commercial and household use applications: a combined case study

In consequent continuation of previous described studies, pre-characterised silicone materials were assessed for chemical and physical parameters during long-term usage. In a particular case study silicone moulds were used in a commercial pizza bakery on a daily basis up to 1700 times. Migration behaviour, uptake of fat, the amount of volatiles and extractables, as well as physical properties (elongation, tensile strength) were monitored for the whole period. The main question was whether a significant degradation or even breakdown of the silicone elastomer could take place yielding enhanced migration of dimethyl siloxanes. Oligomeric dimethyl siloxanes are reaction side-products of the polymerisation process and despite their origin as so-called non-intentionally added substances (NIAS) were found to be the by far most dominating constituents of the overall migration. Furthermore, the influence of long-term thermal stress on the functionality of the elastomer was proven. Migration into food was determined by ¹H-NMR and was found to decrease during the experiment from values between 11 and 18?mg?kg^?1 to levels below the limit of detection (LOD?<?1?mg?kg^?1). No formation of migrating siloxanes beside the initial amount in the new, unused moulds could be observed. The loss of extractable siloxanes of the used compared with the new moulds was compensated by an uptake of fat and other lipophilic food constituents. The release of volatile organic compounds (VOC) decreased from 0.44% for the new moulds to 0.14% for the longest used ones (about 1700 individual uses; the corresponding summarised baking time was approximately 400?h at 180°C). GC-MS analysis of evaporating volatile compounds showed only cyclic oligomers for the new moulds but exclusively incorporated food components for the heavily used moulds. The physical properties of the silicone moulds remained almost constant during the experiment; no limitations in function due to the repeated thermal stress were observed. Similar results were obtained for baby teats under household conditions of use: a 100 times repeated simulated use in contact with milk followed by subsequent microwave sterilisation did not influence the function or mechanical properties. Because milk is only a weak extracting agent no significant changes in the amount of extractable siloxanes between new and used teats could was seen. Again an uptake of fat was seen and the amount of VOC decreased from 0.26% to 0.17%.