Determination of diffusion and partition coefficients of model migrants by direct contact and vapour phase transfer from low-density polyethylene films into cake

The aim of the present study was to determine the migration kinetics of one photoinitiator, benzophenone, and two optical brighteners, Uvitex OB and 1,4-diphenyl-1,3-butadiene (DPBD), from low-density polyethylene (LDPE) films into cake. Transfer was assessed by both direct contact and also the vapour phase.

To perform the migration tests by direct contact, plastic films enriched with the additives were placed between two cake slices. To evaluate the migration through the gas phase, cake and the fortified LDPE film were placed with no direct contact in a glass container that was hermetically closed. Samples were stored at different time–temperature conditions.

Target compounds were extracted from the films with ethanol (70°C, 24 h) and analysed by HPLC-DAD. Relevant parameters such as partition and diffusion coefficients between food and plastic film were calculated. The Arrhenius equation was applied to estimate the diffusion coefficient at any temperature.

The data indicate that migration of benzophenone occurs in a significant extent into cake by both direct contact and through the gas phase (no direct contact). Conversely, very little migration occurred for Uvitex OB by direct contact and none through the gas phase. Results for benzophenone suggest that migration through the gas phase should be considered when evaluating migration from food packaging materials into food.     

The specific diffusion behaviour in paper and migration modelling from recycled board into dry foodstuffs

Recycled board plays an important role in food packaging, but the great variety of organic impurities must be considered as potential food contaminants. The diffusion behaviour of the impurities is significantly different from that in plastic materials. The two-layer concept for paper and board introduced recently is now treated in more detail. In the rate-determining surface region the diffusion coefficients of the n-alkanes in the homologous series with 15–35 carbon atoms decrease proportionally as their vapour pressures. This leads to a different equation of the diffusion coefficients in comparison with that for the core layer. Different polarities of the migrants have additional influences on the diffusion due to their interactions with the fibre matrix. A new analytical method for the quantification of aromatic impurities has previously been developed. Based on this method and on the described diffusion behaviour, a migration model for specific and global mass transfer of impurities from recycled board into dry food and food simulants is given.     

Study of the partition coefficients Kp/f of seven model migrants from LDPE polymer in contact with food simulants

This study evaluated the influence of parameters such as temperature and type of low-density polyethylene (LDPE) film on the log K_p/f values of seven model migrants in food simulants. Two different types of LDPE films contaminated by extrusion and immersion were placed in contact with three food simulants including 20% ethanol, 50% ethanol and olive oil under several time–temperature conditions. Results suggest that most log K_p/f values are little affected by these parameters in this study. In addition, the relation between log K_p/f and log P_o/w was established for each food simulant and regression lines, as well as correlation coefficients, were calculated. Correlations were compared with data from real foodstuffs. Data presented in this study could be valuable in assigning certain foods to particular food simulants as well as predicting the mass transfer of potential migrants into different types of food or food simulants, avoiding tedious and expensive laboratory analysis. The results could be especially useful for regulatory agencies as well as for the food industry.     

Development of a new modelling tool (FACET) to assess exposure to chemical migrants from food packaging

The approach used to obtain European Union-wide data on the usage and concentration of substances in different food packaging materials is described. Statistics were collected on pack sizes and market shares for the different materials used to package different food groups. The packaging materials covered were plastics (both flexible and rigid), metal containers, light metal packaging, paper and board, as well as the adhesives and inks used on them. An explanation as to how these data are linked in various ways in the FACET exposure modelling tool is given as well as an overview of the software along with examples of the intermediate tables of data. The example of bisphenol A (BPA), used in resins that may be incorporated into some coatings for canned foodstuffs, is used to illustrate how the data in FACET are combined to produce concentration distributions. Such concentration distributions are then linked probabilistically to the amounts of each food item consumed, as recorded in national food consumption survey diaries, in order to estimate exposure to packaging migrants. Estimates of exposure are at the level of the individual consumer and thus can be expressed for various percentiles of different populations and subpopulations covered by the national dietary surveys.     

Assessment of the migration potential of nanosilver from nanoparticle-coated low-density polyethylene food packaging into food simulants

An experimental nanosilver-coated low-density polyethylene (LDPE) food packaging was incubated with food simulants using a conventional oven and tested for migration according to European Commission Regulation No. 10/2011. The commercial LDPE films were coated using a layer-by-layer (LbL) technique and three levels of silver (Ag) precursor concentration (0.5%, 2% and 5% silver nitrate (AgNO₃), respectively) were used to attach antimicrobial Ag. The experimental migration study conditions (time, temperature and food simulant) under conventional oven heating (10 days at 60°C, 2 h at 70°C, 2 h at 60°C or 10 days at 70°C) were chosen to simulate the worst-case storage period of over 6 months. In addition, migration was quantified under microwave heating. The total Ag migrant levels in the food simulants were quantified by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Mean migration levels obtained by ICP-AES for oven heating were in the range 0.01–1.75 mg l^?1. Migration observed for microwave heating was found to be significantly higher when compared with oven heating for similar temperatures (100°C) and identical exposure times (2 min). In each of the packaging materials and food simulants tested, the presence of nanoparticles (NPs) was confirmed by scanning electron microscopy (SEM). On inspection of the migration observed under conventional oven heating, an important finding was the significant reduction in migration resulting from the increased Ag precursor concentration used to attach Ag on the LDPE LbL-coated films. This observation merits further investigation into the LbL coating process used, as it suggests potential for process modifications to reduce migration. In turn, any reduction in NP migration below regulatory limits could greatly support the antimicrobial silver nanoparticle (AgNP)-LDPE LbL-coated films being used as a food packaging material.     

Controlled release of α-tocopherol,quercetin, and their cyclodextrin inclusion complexes from linear low-density polyethylene (LLDPE) films into a coconut oil model food system

Polymer additive migration into a food product is dependent upon numerous factors including the original concentration of the additive in the polymer, its solubility in the food, its diffusion coefficient in the polymer, its partition coefficient between the polymer and food, temperature, and time. The limited solubility of quercetin in linear low-density polyethylene (LLDPE) did not allow release from the film due to phase segregation of the quercetin in the bulk polymer. Increasing the molecular weight of α-tocopherol by β-cyclodextrin inclusion complexation can greatly reduce its diffusion coefficient in LLDPE. Ziegler–Natta and metallocene LLDPE contain different crystalline structure morphologies and diffusion path networking arrangements that allow for differences in additive release rates. Effective controlled-release packaging should combine β-cyclodextrin complexation of additives and polymer morphology control to target delivery of an optimal antioxidant concentration to achieve prolonged activity, resulting in extended shelf life foods.     

Study of silver ion migration from melt-blended and layered-deposited silver polyethylene nanocomposite into food simulants and apple juice

Colloidal silver nanoparticles were prepared via chemical reduction using polyethylene glycol (PEG) as a reducing agent, stabiliser and solvent. Silver polyethylene nanocomposites were produced via two methods, namely: melt blending and layer-by-layer (LBL) deposition of silver nanoparticles onto a polyethylene film. The silver ion release from either melt-blended or LBL-deposited nanocomposites into a food simulant and apple juice during 30 days at 4°C and 40°C was determined by atomic absorption spectroscopy. The effects of incorporating or coating of silver nanoparticles, silver concentration, contact media, temperature and time on silver ion migration were evaluated using factorial design. The diffusion coefficients of silver ions into the food simulants and apple juice were calculated using the Miltz model. The results indicated that the production method of nanocomposite, silver concentration, temperature, time and contact media showed a significant effect (p < 0.05) on silver ion migration. The quantity of silver ion migration from the nanocomposites into the food simulants and apple juice was less than the cytotoxicity-level concentration (10 mg kg^?1) in all cases over 30 days. The coating of silver nanoparticles, higher silver concentration in the nanocomposite, higher temperature and acidic property of contact liquid all promoted the silver ion release from the nanocomposite films. The migration of silver ions from nanocomposites obeyed first-order diffusion kinetics.     

Retention of α-tocopherol in low-density polyethylene (LDPE) and polypropylene (PP) in contact with foodstuffs and food-simulating liquids

Alpha-tocopherol occurs as a natural antioxidant in many foods and has also found use as a stabiliser in polymeric packaging materials. During storage of a food in contact with a plastic material, α-tocopherol may be released from the packaging material and transferred into the food. An active packaging application with the transfer of a substance, such as an antioxidant, from a packaging material to a food may help to prolong the shelf-life of the food. In this study, the retention of α-tocopherol in low-density polyethylene (LDPE) and polypropylene (PP) was investigated for contact with liquid foods with different fat contents and food simulants with different ethanol contents. The PP film exhibited excellent retention of α-tocopherol when in contact with all media, whereas some losses were observed from the LDPE film. A number of factors including fat, alcohol and organic acid contents of the various foodstuffs seemed to influence the loss of α-tocopherol from the LDPE film. © 1999 Society of Chemical Industry     

Migration measurement and modelling from poly(ethylene terephthalate) (PET) into soft drinks and fruit juices in comparison with food simulants

Poly(ethylene terephthalate) (PET) bottles are widely used for beverages. Knowledge about the migration of organic compounds from the PET bottle wall into contact media is of interest especially when post-consumer recyclates are introduced into new PET bottles. Using migration theory, the migration of a compound can be calculated if the concentration in the bottle wall is known. On the other hand, for any given specific migration limit or maximum target concentration for organic chemical compounds in the bottled foodstuffs, the maximum allowable concentrations in the polymer C _P,0 can be calculated. Since a food simulant cannot exactly simulate the real migration into the foodstuff or beverages, a worse-case simulation behaviour is the intention. However, if the migration calculation should not be too overestimative, the polymer-specific kinetic parameter for migration modelling, the so-called A _P value, should be established appropriately. One objective of the study was the kinetic determination of the specific migration behaviour of low molecular weight compounds such as solvents with relatively high diffusion rates and, therefore, with high migration potential from the PET bottle wall into food simulants in comparison with real beverages. For this purpose, model contaminants were introduced into the bottle wall during pre-form production. The volatile compounds toluene and chlorobenzene were established at concentrations from about 20–30 mg kg^?1 to 300–350 mg kg^?1. Phenyl cyclohexane was present at concentrations of 35, 262 and 782 mg kg^?1, respectively. The low volatile compounds benzophenone and methyl stearate have bottle wall concentrations of about 100 mg kg^?1 in the low spiking level up to about 1000 mg kg^?1 in the highly spiked test bottle. From these experimental data, the polymer specific parameters (A _P values) from mathematical migration modelling were derived. The experimental determined diffusing coefficients were determined, calculated and compared with literature data and an A _P′ value of 1.0 was derived thereof for non-swelling food simulants like 3% acetic acid, 10% ethanol or iso-octane. For more swelling condition, e.g. 95% ethanol as food simulant, an A _P′ value of 3.1 seems to be suitable for migration calculation. In relation to PET recycling safety aspects, maximum concentrations in the bottle wall were established for migrants/contaminants with different molecular weights, which correspond with a migration limit of 10 μg kg^?1. From the experimental data obtained using food simulants and in comparison with beverages, the most appropriate food simulant for PET packed foods with a sufficient but not too overestimative worse-case character was found to be 50% ethanol. In addition, it can be shown that mass transport from PET is generally controlled by the very low diffusion in the polymer and, as a consequence, partitioning coefficients (K _P/F values) of migrants between the polymer material and the foodstuff do not influence the migration levels significantly. An important consequence is that migration levels from PET food-contact materials are largely independent from the nature of the packed food, which on the other hand simplifies exposure estimations from PET.     

Determining the effective diffusion coefficient of water in banana (Prata variety) during osmotic dehydration and its use in predictive models

The objective of this study was to develop a suitable method for determining the effective diffusion coefficient of water in banana (Prata variety) from experimental data of osmotic dehydration (OD) and using this coefficient for predicting dehydration of the same sample under other situations. Different methods were compared in order to determine the best coefficient to be used in the predictive models. The analytical solution of the diffusion equation allowed estimating averaged values of coefficients between the initial moisture and the average sample moisture at a given instant. The numerical method allowed estimating how the effective diffusion coefficient varies with the moisture. The models prediction ability were validated using a dehydration data set not used for estimating the diffusion coefficients. The use of the diffusive model with a coefficient that depends on the moisture content has the best predictive ability, because it takes into account that the coefficient decreases during the OD.     

Survey on the occurrence of photo-initiators and amine synergists in cartonboard packaging on the German market and their migration into the packaged foodstuffs

In a surveillance study from 2008 to 2011, in total 310 food products, predominately packed in cartonboard, were collected from the German market. First, the packaging materials were analysed for their content of six photo-initiators and five amine synergists by high-performance liquid chromatography with diode array detection (HPLC-DAD). If high amounts of these substances were detected, subsequently the foodstuffs were analysed by means of HPLC-MS or tandem MS, respectively. Benzophenone (BP) was detected in 49% of the packaging materials and was thus the most often determined compound, followed by 4-methylbenzophenone (MBP, 8%), 1-hydroxy-cyclohexylphenylketone (HCHPK, 7%) and methyl-o-benzoylbenzoate (MOBB, 5%). In total, 99 foodstuffs were analysed and in 20 cases one or more photo-initiators and/or amine synergists were detected in quantities above the legally acceptable limits in food. This resulted in several notifications in the European Rapid Alert System for Food and Feed (RASFF); the best known is MBP in breakfast cereals. Contamination of the foodstuff by the photo-initiators and/or amine synergists also occurred when it was in indirect contact with the printed packaging material and no adequate barrier material was used to prevent migration. The data also clearly demonstrate that polyethylene films are not suitable to inhibit migration. Storage of samples until the best before date showed that HCHPK, BP and MBP migrate very easily via the gas phase. In contrast, 4-phenylbenzophenone and 4,4′-bis(diethylamino)benzophenone migrated only very slowly or, respectively, not in quantifiable amounts into the foodstuffs. Differences in transfer rates for HCHPK, BP and MBP from several packagings into food and Tenax^®, respectively, lead to the assumption that both the food matrix as well as the extent of cross-linking of the printing ink during curing may have an influence on the level of migration.     

Migration of antimony from PET trays into food simulant and food: determination of Arrhenius parameters and comparison of predicted and measured migration data

Migration experiments with small sheets cut out from ovenable PET trays were performed in two-sided contact with 3% acetic acid as food simulant at various temperatures. The fraction of diffusible antimony (Sb) was estimated to be 62% in the PET sample under study. Apparent diffusion coefficients of Sb in PET trays were determined experimentally. Measurement of migration between 20 and 150°C yielded a linear Arrhenius plot over a wide temperature range from which the activation energy (E _a) of 188?±?36?kJ?mol^?1 and the pre-exponential factor (D ₀) of 3.6?×?10¹⁴?cm²?s^?1 were determined for diffusing Sb species. E _a was similar to previously reported values for PET bottles obtained with a different experimental approach. E _a and D ₀ were applied as model parameters in migration modelling software for predicting the Sb transfer in real food. Ready meals intended for preparation in a baking oven were heated in the PET trays under study and the actual Sb migration into the food phase was measured by isotope dilution ICP-MS. It was shown that the predictive modelling reproduces correctly experimental data.     

Migration of epoxidized soybean oil (ESBO) and phthalates from twist closures into food and enforcement of the overall migration limit

Nineteen samples of food in glass jars with twist closures were collected by the national food inspectors at Danish food producers and a few importers, focusing on fatty food, such as vegetables in oil, herring in dressing or pickle, soft spreadable cheese, cream, dressings, peanut butter, sauces and infant food. The composition of the plasticizers in the gaskets was analysed by gas chromatography with flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Epoxidized soybean oil (ESBO) and phthalates were determined in the homogenized food samples. ESBO was the principal plasticizer in five of the gaskets; in 14 it was phthalates. ESBO was found in seven of the food samples at concentrations from 6 to 100 mg kg^?1. The highest levels (91–100 mg kg^?1) were in oily foods such as garlic, chilli or olives in oil. Phthalates, i.e. di-iso-decylphthalate (DIDP) and di-iso-nonylphthalates (DINP), were found in seven samples at 6–173 mg kg^?1. The highest concentrations (99–173 mg kg^?1) were in products of garlic and tomatoes in oil and in fatty food products such as sauce béarnaise and peanut butter. For five of the samples the overall migration from unused lids to the official fatty food simulant olive oil was determined and compared with the legal limit of 60 mg kg^?1. The results ranged from 76 to 519 mg kg^?1 and as a consequence the products were withdrawn from the market.     

Antioxidants from barley husks impregnated in films of low-density polyethylene and their effect over lipid deterioration of frozen cod (Gadus morhua)

BACKGROUND: The changes in quality of cod fillets packaged in films with and without antioxidants during 12 months of frozen storage at ? 20 °C were investigated in the present study. The following parameters were determined in order to study lipid hydrolysis and primary and secondary lipid oxidation in the samples during frozen storage: peroxide value, conjugated dienes, conjugated triene hydroperoxides, free fatty acids, totox value, thiobarbituric acid‐reactive substances and p‐anisidine value. RESULTS: Films containing antioxidants isolated from barley husks were effective in slowing down lipid hydrolysis and primary and secondary lipid oxidation processes. Secondary lipid oxidation reached maximum values in the 12th month of storage in control samples and samples packaged with antioxidant‐containing film. Maximum lipid hydrolysis and lipid oxidation values for control cod samples were significantly higher than the maximum values found in samples packaged with antioxidant‐containing film. CONCLUSION: The results confirm the efficacy of natural antioxidants derived from barley husks in slowing down lipid hydrolysis and increasing the oxidative stability of cod flesh. They also demonstrate the potential usefulness of natural antioxidants extracted from barley husks in the development of active packaging films for food preservation. Copyright © 2011 Society of Chemical Industry     

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.