a b s t r a c tThe migration of components from paper into Tenax Ò was studied to determine the influence of molecular size and chemical character of the migrant and the influence of paper characteristics in the migration process. The Weibull model was applied because Fick's 2nd law of diffusion gave poor fits in some cases. The migration pattern depended on the migrants molecular size and was independent of temperature in the studied range. The migration rate decreased with the migrant molecular size. The influence of the migrants character (polarity and vapour pressure) on the migration behaviour was also studied: nonpolar migrants with high vapour pressure presented low relative migration values and polar migrants presented high values of relative migration. Results indicated that the apparent partition coefficient between paper and the simulant Tenax Ò increased with the migrant vapour pressure and with both the paper grammage and the recycled pulp content.
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SUMMARYThe determination of the oxygen transmission rate (OTR) through closures in glass bottles is becoming increasingly important for quality control of different batches and for development purposes. The Mocon method for measuring OTR is globally accepted and used in different applications. However, one of the major drawbacks this method presents when applied to bottle/closures systems is the long time required to obtain stable measurements when 40 mm long closures are tested. This paper describes a method to obtain OTR values with samples of reduced thickness with much shorter measurements time, since the condition of steady state during measurements is achieved faster and compares the estimated full-length commercial closure OTR with experimental values.
A simple and accessible gas chromatography–mass spectrometry method was developed to determine photoinitiators (PIs) in plastics for food contact and their migration into Tenax®. The method showed analytical performance suitable for compliance assessment. The limit of detection values found were as follows: for benzophenone and 4‐(4‐morpholinyl)benzaldehyde ~3 μg kg−1 food (6 dm2 kg−1 food), for 4‐methylbenzophenone and ethyl‐4‐(dimethylamino)‐benzoate ~1.5 μg kg−1 food and for 2‐ethylhexyl 4‐(dimethylamino)benzoate ~43 μg kg−1 food. For all the other PIs studied, limits of detection lower than 1 μg kg−1 food were found.
The method was applied to analyse samples of plastic baby bibs collected in European market. Results indicate that several unauthorised PIs are in use to print bibs. The most commonly detected PIs were benzophenone detected in nearly all samples and isopropylthioxanthone quantified in 12 out of 22 samples. Several non‐evaluated PIs were detected: triphenyl phosphate, 2‐ethylanthraquinone, 2,2‐dimethoxy‐2‐phenylacetophenone, 4‐(4‐methylphenyltio)benzophenone, 1‐hydroxycyclohexyl phenyl ketone and 4,4′‐bis(diethylamino)‐benzophenone. These two latter PIs were found at the highest concentration (more than 100 μgg−1).
Testing a selection of samples for migration into Tenax® gave results exceeding the applicable migration limit for 1‐hydroxycyclohexyl phenyl ketone with 0.532 mg kg−1 (specific migration limit = 0.01 mg kg−1) and for methyl 2‐benzoylbenzoate with 0.182 mg kg−1 (specific migration limit = 0.05 mg kg−1). Although the results may be affected by a certain overestimation degree given the experimental conditions, they certainly flag an area of potential interest for surveillance and more detailed risk evaluation, particularly because bibs are often not seen by industry as food contact materials, and surveillance actions are not systematically acted.
Hemp (Cannabis sativa) stalk fibres from industry residues were incorporated into polybutylene adipate terephthalate, a synthetic biodegradable polyester, to produce films and paper coatings. The lignocellulosic components and the chemical composition of the fibres were analysed, and the results highlight the bioactivity due to cannabinoids, alkanoids, and lignin, among others, making the fibres attractive for active food packaging. The incorporation, without chemical modification, of 2% (w/w) hemp in the PBAT matrix increased the water vapour permeability of PBAT to around 22%. The impact on mechanical properties was determined, and the results show that the PBAT/hemp film is less stretchable but stronger than the pure PBAT film. The incorporation of hemp enhanced significantly the compostability of PBAT. The PBAT/hemp films and paper coatings composted two times faster than those using pure PBAT.
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