Migration from the gaskets of lids into oily foods: first results on polyadipates

The migration from the gaskets of plasticized PVC in metal closures usually far exceeds the legal limits if the packed food contains some free oil. If the gaskets continue to consist of PVC, polyadipates seem to be the only acceptable plasticizers, although difficult to work with: they render the plastisol highly viscous and make it difficult to place a uniform ring into the lid. This suggests dilution with plasticizers of low viscosity. Results from simulating tests (olive oil in direct contact) confirm that the migration of polyadipates is far lower, but also that even the migration of minor portions of diluting plasticizers is critical for the overall migration. The first tests with 11 packed foods, stored and repeatedly shaken for up to 2 years, show migration of polyadipate clearly below the limits. It was lower than that determined by simulating tests, whereas the migration of ESBO was several times higher, questioning the suitability of presently applied testing.     

On the origin of benzene, toluene, ethylbenzene, and the xylenes in virgin olive oil-further results

Investigations into the sources of contamination of virgin olive oil by gasoline components were concluded. Olives on the tree contained volatile aromatic hydrocarbons at concentrations exceeding those corresponding to the equilibrium with the environment. Present knowledge indicates that up to 10 g/kg of benzene and 250 g/kg for the sum of benzene, toluene, and the C₂-benzenes must be considered as possible background concentrations. Aside from the oil mills, the rooms for intermediate storage of the olives were found to be an important source of contamination by gasoline vapours, since they often contain vehicles and other gasoline-driven engines. Parking of a small, hot grass mower into a similar room released an amount of gasoline that was sufficient to contaminate the oil in olives above the proposed limit by a factor of 100. Recommendations are derived for the producers to avoid contamination of olive oil with gasoline components.     

French fries with less than 100 μg/kg acrylamide. A collaboration between cooks and analysts

In collaboration with cooking experts, the preparation of French fries in oil and in ovens was optimized, aiming at optimum culinary quality combined with a minimum acrylamide content. French fries with 40–70 g/kg acrylamide were consistently produced, i.e. with 5–10 times less acrylamide than currently normal. The raw potato should contain little reducing sugars, i.e. be of a suitable cultivar, and storage at temperatures below about 10 °C must be avoided. After cutting and elimination of the fines, the potato is immersed in standing cold or boiler-warm water for some 15 min in order to extract asparagine and sugars from the surface without washing out the starch. Pre-frying in oil (ca. 140 °C for 2.5 min) improves crispiness. Frying should occur at an initial oil temperature of about 170 °C, adding some 100 g potato/l oil. Since acrylamide formation increases exponentially towards the end of the process, the most important factor to keep acrylamide contents low is the determination of the proper end point of the frying process. French fries should be crispy with slight browning of the tips to achieve the typical flavor, but without general browning. Preparation in the oven, starting from frozen prefabricates, requires temperatures of around 190 °C or 220 °C, depending on whether or not the air is circulated. The proper determination of the end point is again the most critical step.     

Migration of mineral oil from printed paperboard into dry foods: survey of the German market

From the German market, 119 samples of dry food were analyzed for the migration of mineral oil. The products selected were packed in paperboard boxes and intended for storage for extended periods of time at ambient temperature. The 0.6 mg/kg limit for mineral oil saturated hydrocarbons (MOSH) derived from the WHO/JECFA evaluation was frequently exceeded by a factor of 10–100. Typically, 10–20% of the migrating mineral oil consisted of aromatic hydrocarbons (MOAH). Most samples were merely 2–3 months old and far from the end of their shelf life (usually 1–3 years). From the assumption that about 70% of the MOSH and MOAH which are eluted from GC up to the C₂₄ n-alkane (<C24) end up in the food (potential of migration), it was estimated that migration might almost triple before the products reach the end of their shelf life, reaching 31 mg/kg on average, with several samples exceeding 100 mg/kg. At the time of the analysis, products without an internal bag and with a bag of paper or polyethylene reached up to about 80% of the potential of migration (average, 30–50%). Bags of polypropylene, acrylate-coated polypropylene, PET or with an aluminum layer seemed to block migration (with one possible exception), but it was premature to reach conclusions on long-term functional barrier properties. From the comparison with <C₂₄ MOSH concentrations in unprinted recycled paperboards, it was estimated than on average about a quarter of the migrating mineral oil was from printing ink used for decorating the box.     

Analysis of saturated and aromatic hydrocarbons migrating from a polyolefin-based hot-melt adhesive into food

Hot-melt adhesives are widely utilised to glue cardboard boxes used as food packaging material. They have to comply with the requirements of Article 3 of the European Framework Regulation for food contact materials (1935/2004). The hot melt raw materials analysed mainly consisted of paraffinic waxes, hydrocarbon resins and polyolefins. The hydrocarbon resins, functioning as tackifiers, were the predominant source of hydrocarbons of sufficient volatility to migrate into dry foods: the 18 hydrocarbon resins analysed contained 8.2–118 g kg^–1 saturated and up to 59 g kg^–1 aromatic hydrocarbons eluted from GC between n-C₁₆ and n-C₂₄, substantially more than the paraffinic waxes and the polyolefins. These tackfier resins, especially the oligomers ≤ C₂₄, have been characterised structurally by GC×GC-MS and ¹H-NMR spectroscopy. Migration into food was estimated using a simulating system with polenta as food simulant, which was verified by the analysis of a commercial risotto rice sample packed in a virgin fibre folding box sealed with a hot melt. About 0.5–1.5% of the potentially migrating substances (between n-C₁₆ and n-C₂₄) of a hot melt were found to be transferred into food under storage conditions, which can result in a food contamination in the order of 1 mg kg^–1 food (depending on the amount of potentially migrating substances from the hot melt, the hot melt surface, amount of food, contact time etc.). Migrates from hot melts are easily mistaken for mineral oil hydrocarbons from recycled cardboard.     

Food Contamination with Organic Materials in Perspective: Packaging Materials as the Largest and Least Controlled Source? A View Focusing on the European Situation

The comparison of the various sources of food contamination with organic chemicals suggests that in the public, but also among experts, the perception of risk is often distorted. Firstly, neither pesticides nor environmental pollutants contribute the most; the amount of material migrating from food packaging into food may well be 100 times higher. Secondly, control of these large migrants is often lagging behind the standards set up for other sources, since many of the components (particularly those not being "starting materials") have not been identified and, thus, not toxicologically evaluated. Finally, attitudes towards different types of food contaminants are divergent, also reflected by the legal measures: for most sources of food contamination there are strict rules calling for minimization, whereas the European packaging industry has even requested a further increase in the tolerance to as close as possible to the limit set by the toxicologists. This paper calls for a more realistic perception and more coherent legal measures-and improvements in the control of migration from packaging material.     

In GC-MS, acrylamide from heated foods may be coeluted with 3-hydroxy propionitrile

Using the widely applied GC-MS method for direct analysis of acrylamide in heated foods, 3-hydroxy propionitrile (3-HPN) may be coeluted with acrylamide causing falsely high acrylamide values. Since it is often virtually the only peak in the gas chromatogram, such coelution is unexpected. 3-HPN was found in pears, apples, plums and tomatoes, independently of whether these were heated; in a sample of pears it quantitated as 2,800 μg/kg apparent acrylamide. Breakfast cereals, muesli and bakery ware with fruits may contain 3-HPN. The problem can be solved by tuning the chromatographic conditions to separate the two components or by a stationary phase other than the Carbowaxes usually used.     

On the origin of benzene, toluene, ethylbenzene and xylene in extra virgin olive oil

Concentrations of benzene, toluene, C₂-benzenes and styrene were determined in olives and the oils produced thereof, as well as at various intermediate steps during production. Concentrations were compared to those found in samples of air taken from the olive grove and the olive mills. In an exposition experiment in the laboratory, olives absorbed aromatic compounds, approaching saturation corresponding to the partition coefficient between air and oil. However, concentrations in olives delivered to the mills were 4–10 times higher than expected from the analysis of the air in the olive grove. In the olive mills, concentrations were increased further by a factor of up to 2 because of uptake from air which contained high concentrations of aromatics. Styrene concentrations strongly increased during storage of crushed olives at ambient temperature, which confirms the hypothesis that styrene is a product of metabolism.

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Über die Herkunft von Benzol, Toluol, Ethylbenzol und Xylol in nativen Olivenölen

Zusammenfassung Gehalte von Benzol, Toluol, C₂-Benzolen und Styrol wurden in Oliven, den daraus gewonnenen Ölen sowie Zwischenstufen der Ölproduktion gemessen und mit den Konzentrationen in der Luft des Olivenhains und der Ölmühlen verglichen. In Expositionsversuchen im Labor nahmen Oliven annähernd soviel Aromaten auf, wie Sättigung gemäß dem Verteilungskoeffizienten zwischen Luft und Öl entspricht. Die Konzentrationen in den an die Mühlen gelieferten Oliven lagen jedoch 4–10mal höher als die Gehalte in der Luft des Olivenhains erwarten ließen. In der Ölmühle erhöhten sich die Konzentrationen nochmals um einen Faktor bis zu zwei wegen höheren Aromatengehalten in jener Luft. Styrol stieg bei der Lagerung zerquetschter Oliven bei Raumtemperatur stark an, was die Vermutung bestätigt, daß es sich um ein Metabolisierungsprodukt handelt.

     

Is recycled newspaper suitable for food contact materials? Technical grade mineral oils from printing inks

Recycled paper and board used in food packaging materials (boxes, paper bags) often cause migration of mineral oil into food at levels which are unacceptable according to present toxicological assessments. When foods in recycled board are densely packed into larger boxes or onto pallets, most of the hydrocarbons up to n-C₂₀ may migrate into the packed food within a few weeks, those up to n-C₂₈ at a decreasing rate. Unprinted recycled board contained 300–1,000 mg/kg mineral oil <n-C₂₈. The main sources are the inks used for printing newspapers: newspapers contained roughly 3,000 mg/kg mineral oil <n-C₂₈. These mineral oils fall into classes for which JECFA established a tolerable daily intake of 0.01 mg/kg body weight. Using standard assumptions for calculating specific migration limits, a maximum tolerable concentration in food of 0.6 mg/kg is derived. This evaluation assumes highly refined white oils, whereas the oils found in recycled board are of technical quality and contain 15–25% aromatic compounds, predominantly with 1–3 aromatic rings, as shown by comprehensive GC × GC. This finding precipitates authorities into a dilemma: recycling is supported for the sustainable use of materials, but on the basis of present toxicological assessments the migration is often far beyond acceptable.     

Compositional GC-FID analysis of the additives to PVC, focusing on the gaskets of lids for glass jars

A gas chromatographic (FID) method is described which aims at the quantitative compositional analysis of the additives in plasticized PVC, particularly the plastisols used as gaskets for lids of glass jars. An extract of the PVC is analysed directly as well as after transesterification to ethyl esters. Transesterification enables the analysis of epoxidized soya bean and linseed oil (ESBO and ELO) as well as polyadipates. For most other additives, the shifts in the chromatogram resulting from transesterification is used to confirm the identifications made by direct analysis. In the gaskets of 69 lids from the European market used for packaging oily foods, a broad variety of plastisol compositions was found, many or possibly all of which do not comply with legal requirements. In 62% of these lids, ESBO was the principal plasticizer, whereas in 25% a phthalate had been used.