Exposure to antimony from polyethylene terephthalate (PET) trays used in ready-to-eat meals

Antimony residues, a result of the use of a polycondensation catalyst in the production of polyethylene terephthalate (PET) oven-proof trays, were analysed in ready-to-eat meals. The toxicity of antimony has raised concerns about consumer safety; therefore, the migration of small fractions of these residues into ready meals and foods as a result of cooking directly in the PET trays was studied. A straightforward approach of measuring real samples was selected to obtain accurate exposure data. Background antimony concentration was determined separately from a series of lunch meals, which ranged from not detectable to 3.4 µg kg^-1. Microwave and conventional oven-cooking caused a distinct increase in the concentration of antimony in food and ready meals of 0-17 and 8-38 µg kg^-1, respectively, depending, to a certain extent, on the industrial preparations. The migrated quantities of antimony corresponded to 3-13 µg. For comparison, PET roasting bags and ready-made dough products in PET baking dishes were also evaluated. About half of the products prepared at a temperature of 180°C exceeded the specific migration limit set for food contact material by the European Commission. However, the migrated amounts of antimony relative to the accepted tolerable daily intake (TDI) show that exposure from this type of food is currently not of toxicological concern.     

Migration into food of polyethylene terephthalate (PET) cyclic oligomers from PET microwave susceptor packaging

A quantitative method has been developed to measure the migration of polyethylene terephthalate (PET) cyclic oligomers from aluminized PET susceptor film-type food packaging into several food types. Microwaveable French fries, popcorn, fish sticks, waffles and pizza sold in susceptor-type packaging were purchased in local markets, cooked according to package instructions and analysed for PET oligomers. Appropriate food blanks were cooked in glass containers. Quantities of PET oligomers found in the foods ranged from less than 0.012 micrograms/g to approximately 7 micrograms/g.     

Migration of a UV stabilizer from polyethylene terephthalate (PET) into food simulants

The migration characteristics of the UV stabilizer Tinuvin 234 (2-(2H-benzotriazol-2-yl)-4,6-bis (1-methyl-1-phenylethyl)phenol) into food simulants has been measured from polyethylene terephthalate (PET) using HPLC with UV detection. Ethanol/water, isooctane and a fractionated coconut oil simulant (Miglyol®) were used as food simulating solvents. The migration characteristics were measured at temperatures in the range of 40-70°C. Diffusion coefficients were determined to be in the range of 1 × 10^-14 cm² s^-1 to 1 × 10^-18 cm² s^-1. At 40°C, the amount of migration into 95% ethanol after 10 days was 2 μg dm^-2. Isooctane is determined to be a good fatty food simulant that provides similar results for PET to those of fatty foods.     

Migration of formaldehyde and acetaldehyde into mineral water in polyethylene terephthalate (PET) bottles

The levels of formaldehyde (FA) and acetaldehyde (AA) in polyethylene terephthalate (PET) bottles and in commercial mineral water are reported. All the water samples bottled in Japan contained detectable levels of FA (10.1-27.9 μg l^-1) and AA (44.3-107.8 μg l^-1). Of 11 European bottled water samples, eight did not contain either FA or AA, while the remaining three had detectable levels of FA (7.4-13.7 μg l^-1) and AA (35.9-46.9 μg l^-1). In three North American bottled water samples, two contained FA (13.6 and 19.5 μg l^-1) and AA (41.4 and 44.8 μg l^-1), and one did not. Regardless of the region of origin, all the sterilized water samples contained FA and AA, whilst in contrast, none of the unsterilized water without carbonate contained FA or AA. Of the carbonated water samples, three contained FA and AA, and one did not. When fortified with FA and AA, the commercial water sample without otherwise detectable FA and AA was able to reduce levels, although the commercial water sample containing FA and AA could not. The presence of bacteria in the commercial water samples was investigated using an ATP-based bioluminescent assay and heterotrophic plate count method. The commercial water without FA and AA contained heterotrophic bacteria, whilst the commercial water with FA and AA did not contain detectable bacteria. It is suggested that in this case both FA and AA migrated from PET materials, but were subsequently decomposed by the heterotrophic bacteria in the unsterilized water.     

Structures and flammability properties of polyethylene terephthalate(PET) fibers containing encapsulated carbon materials

In this paper, carbon nanotubes (CNTs) and carbon microspheres (CMSs) have been microencapsulated to obtain microencapsulated carbon nanotubes (MCNTs) and microencapsulated carbon microspheres (MCMSs). Moreover, a series of PET fibers with CNTs/CMSs or MCNTs/MCMSs were prepared by melt spinning. Morphologic structures, mechanical, thermal, and flame retardant properties of MCNTs/MCMSs /PET fibers have been studied by TEM, SEM, electronic tension meter, DSC, TG, limiting oxygen index (LOI), and vertical flammability instruments. The results show that the tensile strength of MCNTs/MCMSs/PET fibers are increased because of better dispersion and compatibility of MCNTs/MCMSs in PET and enhanced orientation degrees of fibers, compared with CNTs/CMSs/PET fibers. Moreover, the highest values of mechanical properties are observed with 0.4 wt% content. Meanwhile, the MCNTs/MCMSs/PET fibers have good thermal stabilities and their fabrics have higher LOI value of 25.3%, reaching B1 class of China standard GB 17591-2006. Overall, this method endowed the MCNTs/MCMSs/PET fibers with the good mechanical and flame-retardant properties.     

低温氩等离子体表面改性提高PET亲水性

为了提高PET材料表面的亲水性,应用低温氩等离子体对PET进行表面处理。对不同等离子体处理工作参数(放电功率、放电时间、工作气压)下PET薄膜表面的水接触角变化进行了规律性和原理分析。用IR和SEM分析了处理前后PET薄膜表面形态的变化。实验结果表明:不同等离子体处理工作参数下PET薄膜表面的水接触角的变化呈现不同的规律性;经等离子体处理后PET薄膜表面CO和CC键的数量增加,酯基数量减少,显著提高了薄膜的亲水性;但是低温氩等离子体处理后的PET薄膜放置一段时间后时效性问题比较明显。     

SiOx layer as functional barrier in polyethylene terephthalate (PET) bottles against potential contaminants from post-consumer recycled PET

The barrier effect of a silicon oxide (SiOx) coating on the inner surface of PET bottles, in terms of the ability to reduce the migration of post-consumer compounds from the PET bottle wall into food simulants (3% acetic acid and 10% ethanol), was investigated. The barrier effect was examined by artificially introducing model substances (surrogates) into the PET bottle wall to represent a worst-case scenario. Test bottles with three different spiking levels up to approximately 1000 mg kg(-1) per surrogate were blown and coated on the inner surface. The SiOx-coated bottles and the non-coated reference bottles were filled with food simulants. From the specific migration of the surrogates with different bottles wall concentrations, the maximum surrogate concentrations in the bottle wall corresponding to migration of 10 microg l(-1) were determined. It was shown that the SiOx coating layer is an efficient barrier to post-consumer compounds. The maximum bottle wall concentrations of the surrogates corresponding to migration of 10 microg l(-1) were in the range of 200 mg kg(-1) for toluene and approximately 900 mg kg(-1) for benzophenone. Consequently, the SiOx coating allows use of conventionally recycled post-consumer PET flakes (without a super-clean recycling process) for packaging aqueous and low alcoholic foodstuffs (under cold-fill conditions) and protects food from migration of unwanted contaminants from post-consumer PET.     

Contamination of bottled waters with antimony leaching from polyethylene terephthalate (PET) increases upon storage

Antimony concentrations were determined in 132 brands of bottled water from 28 countries. Two of the brands were at or above the maximum allowable Sb concentration for drinking water in Japan (2 microg/L). Elevated concentrations of Sb in bottled waters are due mainly to the Sb2O3 used as the catalyst in the manufacture of polyethylene terephthalate (PET(E)). The leaching of Sb from PET(E) bottles shows variable reactivity. In 14 brands of bottled water from Canada, Sb concentrations increased on average 19% during 6 months storage at room temperature, but 48 brands of water from 11 European countries increased on average 90% under identical conditions. A mineral water from France in PET(E), purchased in Germany, yielded 725 ng/L when first tested, but 1510 ng/L when it was stored for 6 months at room temperature; the same brand of water, purchased in Hong Kong, yielded 1990 ng/L Sb. Pristine groundwater containing 1.7+/-0.4 ng/L Sb (n = 6) yielded 26.6+/-2.3 ng/L Sb (n = 3) after storage in PET(E) bottles from Canada for 6 months versus 281+/-38 ng/L Sb (n = 3) in PET(E) bottles from Germany. Tap water bottled commercially in PET(E) in December 2005 contained 450+/-56 ng/L Sb (n = 3) versus 70.3+/-0.3 ng/L Sb (n = 3) when sampled from a household faucet in the same village (Bammental, Germany), and 25.7+/-1.5 ng/L Sb (n = 3) from a local artesian flow.     

Safety evaluation of mechanical recycling processes used to produce polyethylene terephthalate (PET) intended for food contact applications

The development of a scheme for the safety evaluation of mechanical recycling processes for polyethylene terephthalate (PET) is described. The starting point is the adoption of a threshold of toxicological concern such that migration from the recycled PET should not give rise to a dietary exposure exceeding 0.0025 μg kg^–1 bw day^–1, the exposure threshold value for chemicals with structural alerts raising concern for potential genotoxicity, below which the risk to human health would be negligible. It is practically impossible to test every batch of incoming recovered PET and every production batch of recycled PET for all the different chemical contaminants that could theoretically arise. Consequently, the principle of the safety evaluation is to measure the cleaning efficiency of a recycling process by using a challenge test with surrogate contaminants. This cleaning efficiency is then applied to reduce a reference contamination level for post-consumer PET, conservatively set at 3 mg kg^–1 PET for a contaminant resulting from possible misuse by consumers. The resulting residual concentration of each contaminant in recycled PET is used in conservative migration models to calculate migration levels, which are then used along with food consumption data to give estimates of potential dietary exposure. The default scenario, when the recycled PET is intended for general use, is that of an infant weighing 5 kg and consuming every day powdered infant formula reconstituted with 0.75 L of water coming from water bottles manufactured with 100% recycled PET. According to this scenario, it can be derived that the highest concentration of a substance in water that would ensure that the dietary exposure of 0.0025 µg kg^–1 bw day^–1 is not exceeded, is 0.017 μg kg^–1 food. The maximum residual content that would comply with this migration limit depends on molecular weight and is in the range 0.09–0.32 mg kg^–1 PET for the typical surrogate contaminants.     

SiO x layer as functional barrier in polyethylene terephthalate (PET) bottles against potential contaminants from post-consumer recycled PET

The barrier effect of a silicon oxide (SiO _x ) coating on the inner surface of PET bottles, in terms of the ability to reduce the migration of post-consumer compounds from the PET bottle wall into food simulants (3% acetic acid and 10% ethanol), was investigated. The barrier effect was examined by artificially introducing model substances (surrogates) into the PET bottle wall to represent a worst-case scenario. Test bottles with three different spiking levels up to ～1000 mg kg^?1 per surrogate were blown and coated on the inner surface. The SiO _x -coated bottles and the non-coated reference bottles were filled with food simulants. From the specific migration of the surrogates with different bottles wall concentrations, the maximum surrogate concentrations in the bottle wall corresponding to migration of 10 µg l^?1 were determined. It was shown that the SiO _x coating layer is an efficient barrier to post-consumer compounds. The maximum bottle wall concentrations of the surrogates corresponding to migration of 10 µg l^?1 were in the range of 200 mg kg^?1 for toluene and ～900 mg kg^?1 for benzophenone. Consequently, the SiO _x coating allows use of conventionally recycled post-consumer PET flakes (without a super-clean recycling process) for packaging aqueous and low alcoholic foodstuffs (under cold-fill conditions) and protects food from migration of unwanted contaminants from post-consumer PET.     

Evolution of aroma compounds from orange juice stored in polyethylene terephthalate (PET).

The evolution of aroma compounds from orange juice made from concentrate and stored in glass, standard monolayer polyethylene terephthalate (PET 1), multilayer PET (PET 2) and plasma-treated PET (internal carbon coating) (PET 3) was investigated. Bottles were stored at room temperature (20 degrees C) under artificial light. Volatile compounds in orange juice samples and corresponding packaging materials were analysed at zero time and after 2, 3 and 5 months of storage. After 5 months of storage, from 0.2 to 0.3% of the initial amounts of limonene and beta-myrcene in the orange juice had been absorbed by the plastic packaging materials. Statistical analyses showed that the evolution of aroma compounds was strongly correlated to the duration of storage, but not to the type of packaging material. Indeed, whatever the stored orange juice samples, the same evolutions were observed, with a decrease in aldehydes and ketones, esters, aliphatic alcohols, sesquiterpene and monoterpene alcohols, and an increase in two aliphatic and monoterpene alcohols (i.e. furfural and 4-vinylguaicol). The results suggest that the losses of aroma compounds from the juice could be attributed to the high acidity of the matrix, implying acid-catalysed reactions. Finally, PET packaging materials and their corresponding oxygen permeabilities showed no correlation with the loss of aroma compounds.     

Enhancing the flame retardant of polyethylene terephthalate (PET) fiber via incorporation of multi-walled carbon nanotubes based phosphorylated chitosan

Phosphorylated chitosan (PCS) were first deposited on the multi-walled carbon nanotubes (MWNTs) surface via chemical modification to obtain functionalized MWNTs-based PCS (PCS-MWNTs). Then, a series of PET fibers with MWNTs or PCS-MWNTs were prepared via melt spinning. The microstructure and molecular structure of PCS-MWNTs were characterized by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy. The morphological structures, mechanical, thermal, and flame-retardant properties of the PET fibers containing MWNTs or PCS-MWNTs were analyzed by FESEM, therogravimetry, differential scanning calorimetry, cone and electronic tension meter method. The results showed that MWNTs were coated with PCS. Compared to PET fiber, when the content of PCS-MWNTs was 0.9 wt.%, the PCS-MWNTs/PET fibers exhibited an efficient flame-retardant capacity, with the lower heat release rate and total release rate values of 81.03 kW/m² and 39.05 MJ/m², respectively, decreasing by 130.06 kW/m² and 11.87 MJ/m². The thermal stability of PCS-MWNTs/PET fibers strengthened, and the char residue increased from 7.21 to 13.52%. Compared to MWNTs/PET fiber, the crystallization property and tensile strength of PCS-MWNTs/PET fiber improved, because of the good dispersion and strong interface binding force with the PET fiber. Overall, the PCS layer endowed the MWNTs with good dispersion and flame-retardant characteristics.     

Characterization of virgin and recycled poly(ethylene terephthalate) (PET) fibers

In this study, we compared the properties of recycled poly(ethylene terephthalate) (PET) fibers and virgin PET fibers. All these experiments present the differences or similarities between them on surface morphology, mechanical properties, and internal fiber structure. The results show that the surface morphology of both PET fibers is similar. According to the tests on mechanical properties, it can be observed that recycled PET fibers have a higher tensile strength and greater elongation at break. The recycled fiber has a higher degree of crystallinity while with the smaller average crystallite size based on the X-ray diffraction data. In polarized attenuated total reflectance infrared technique, the virgin fibers have a better performance than the recycled ones in orientation. Fourier Transform Infrared spectrum analysis indicates that both kinds of fibers have the similar representative groups.     

Isolation and characterization of Bacillus sp. INT005 accumulating polyhydroxyalkanoate (PHA) from gas field soil

A gram-positive bacterium (designated strain INT005) that accumulated polyhydroxyalkanoate (PHA) was isolated from gas field soil. From its morphological and physiological properties and the partial nucleotide sequence (about 500 bp) of its 16S rDNA, it was suggested that strain INT005 was similar to several species of the genus Bacillus. We confirmed that strain INT005 is a Bacillus sp. The PHA productivities of strain INT005 were higher than those of Bacillus megaterium and Ralstonia eutropha at 37-45 degrees C reported to date, and it was suggested that the PHA synthase of INT005 may exhibit moderate thermostability. The bacterium had the ability to produce poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-6-hydroxyhexanoate-co-3-hydroxyhexanoate) from the appropriate carbon sources. The PHA synthase from INT005 showed similar substrate specificity to those of class I and III PHA synthases and strain INT005 produced PHAs with various monomer compositions. From the analysis of monomer composition and PHA accumulation in the presence of acrylic acid, it was suggested that de novo fatty acid synthesis and beta-oxidation are involved in the PHA synthesis of Bacillus sp. INT005. Since Bacillus sp. INT005 could synthesize PHA even at 45 degrees C and PHAs with various monomer compositions, and only one report on the cloning of the synthesis-related genes from a Bacillus species (B. megaterium) has been published;Bacillus sp. INT005 is thought to be very valuable source of PHA synthesis-related genes.     

Development of an LC-MS/MS method for studying migration characteristics of acetaldehyde in polyethylene terephthalate (PET)-packed mineral water

During storage, acetaldehyde migration from polyethylene terephthalate (PET) bottles can affect the quality of mineral water even in the low µg l^?1 range negatively, as it features a fruity or plastic-like off-flavour. For a sensitive and fast analysis of acetaldehyde in mineral water, a new analysis method of 2,4-dinitrophenylhydrazine (DNPH) derivatisation followed by HPLC-electrospray tandem mass spectrometry (ESI-MS/MS) was developed. Acetaldehyde was directly derivatised in the mineral water sample avoiding extraction and/or pre-concentration steps and then analysed by reversed-phase HPLC-ESI-MS/MS using multiple reaction monitoring mode (MRM). Along with method development, the optimum molar excess of DNPH in contrast to acetaldehyde was studied for the mineral water matrix, because no specific and robust data were yet available for this critical parameter. Best results were obtained by using a calibration via the derivatisation reaction. Without any analyte enrichment or extraction, an LOD of 0.5 µg l^?1 and an LOQ of 1.9 µg l^?1 were achieved. Using the developed method, mineral water samples packed in PET bottles from Germany were analysed and the correlation between the acetaldehyde concentration and other characteristics of the samples was evaluated illustrating the applicability of the method. Besides a relationship between bottle size and CO₂ content of the mineral water and acetaldehyde migration, a correlation with acetaldehyde migration and the material composition of the bottle, e.g. recycled PET, was noted. Investigating the light influence on the acetaldehyde migration with a newly developed, reproducible light exposure setup, a significant increase of the acetaldehyde concentration in carbonated mineral water samples was observed.     

Decontamination efficiency of a new post-consumer poly(ethylene terephthalate) (PET) recycling concept

The aim of the study was to investigate and evaluate the cleaning efficiency of a new recycling concept for post-consumer poly(ethylene terephthalate) (PET). The so-called Flake To Resin (FTR®) recycling process produces PET pellets or preforms from conventionally recycled PET flakes for the application in new PET packaging in direct food contact. The investigated process can be considered as 'super-clean' recycling process and was developed to introduce conventional recycled post-consumer (PCR) PET flakes up to an amount of 50% into the pellet and preform production. Within the study the cleaning efficiency of the investigated FTR process was determined by a challenge test. The experimental results obtained from three challenge tests with different input concentrations of the surrogates and different amounts of post-consumer PET flakes show that all applied surrogates are very efficiently removed by the investigated recycling process. The cleaning efficiencies for all surrogates are above 99.9%. In the final product of the process no surrogates could be determined above the detection limits (0.5 mg kg^-1) even if the initial concentrations were in the percentage range. From a migrational point the final product, which are either PET pellets or preforms, was similar to virgin PET. Only the PET typical substances acetaldehyde and ethylene glycol had slightly higher concentrations than found in a conventional PET virgin sample used as reference. The generally accepted migration limit of 10 µg kg^-1 for the surrogates in the final products of the challenge tests is established for all kinds of foodstuffs.     

聚对苯二甲酸乙二醇酯与聚对苯二甲酸丁二醇酯的热分解性能

采用多次线性回归统计法对聚对苯二甲酸乙二醇酯与聚对苯二甲酸丁二醇酯的非等温热分解性能进行了分析,并对二者的热分解情况进行了详细的比较。计算得到热分解动力学参数（反应级数、活化能和指前因子）,并运用动力学方程预估聚对苯二甲酸乙二醇酯与聚对苯二甲酸丁二醇酯在特定条件下的热分解行为,即热分解转化率、温度及时间之间的关系。结果表明,聚对苯二甲酸乙二醇酯的初始分解温度高于聚对苯二甲酸丁二醇酯,但热分解速率较快,这主要与二者的链结构和热分解产生的物质有关。     

Decontamination efficiency of a new post-consumer poly(ethylene terephthalate) (PET) recycling concept

The aim of the study was to investigate and evaluate the cleaning efficiency of a new recycling concept for post-consumer poly(ethylene terephthalate) (PET). The so-called Flake To Resin (FTR®) recycling process produces PET pellets or preforms from conventionally recycled PET flakes for the application in new PET packaging in direct food contact. The investigated process can be considered as ‘super-clean’ recycling process and was developed to introduce conventional recycled post-consumer (PCR) PET flakes up to an amount of 50% into the pellet and preform production. Within the study the cleaning efficiency of the investigated FTR process was determined by a challenge test. The experimental results obtained from three challenge tests with different input concentrations of the surrogates and different amounts of post-consumer PET flakes show that all applied surrogates are very efficiently removed by the investigated recycling process. The cleaning efficiencies for all surrogates are above 99.9%. In the final product of the process no surrogates could be determined above the detection limits (0.5?mg kg^?1) even if the initial concentrations were in the percentage range. From a migrational point the final product, which are either PET pellets or preforms, was similar to virgin PET. Only the PET typical substances acetaldehyde and ethylene glycol had slightly higher concentrations than found in a conventional PET virgin sample used as reference. The generally accepted migration limit of 10?µg kg^?1 for the surrogates in the final products of the challenge tests is established for all kinds of foodstuffs.