Recyclability and Redesign Challenges in Multilayer Flexible Food Packaging-A Review

Multilayer flexible food packaging is under pressure to redesign for recyclability. Most multilayer films are not sorted and recycled with the currently available infrastructure, which is based on mechanical recycling in most countries. Up to now, multilayer flexible food packaging was highly customizable. Diverse polymers and non-polymeric layers allowed a long product shelf-life and an optimized material efficiency. The need for more recyclable solutions asks for a reduction in the choice of material. Prospectively, there is a strong tendency that multilayer flexible barrier packaging should be based on polyolefins and a few recyclable barrier layers, such as aluminium oxide (AlOx) and silicon oxide (SiOx). The use of ethylene vinyl alcohol (EVOH) and metallization could be more restricted in the future, as popular Design for Recycling Guidelines have recently reduced the maximum tolerable content of barrier materials in polyolefin packaging. The substitution of non-recyclable flexible barrier packaging is challenging because only a limited number of barriers are available. In the worst case, the restriction on material choice could result in a higher environmental burden through a shortened food shelf-life and increased packaging weights.

HepGentox: a novel promising HepG2 reportergene-assay for the detection of genotoxic substances in complex mixtures

BACKGROUND

In risk assessment, genotoxicity is a key factor to determine the safety for the consumer. Most in vitro genotoxicity assays were developed for the assessment of pure substances. However, in recent years more attention has been given to complex mixtures, where usually low amounts of a substance are present. For high-throughput screening, a toxicologically sensitive assay should be used, covering a broad range of genotoxic substances and detecting them at low concentrations. HepG2 cells have been recommended as one of the prime candidates for genotoxicity testing, as they are p53 competent, less prone towards cytotoxic effects and tend to have some metabolic activity.

METHODS

A HepG2 liver cell line was characterized for its suitability for genotoxicity assessment. For this, a luciferase based reporter gene assay revolving around the p53 pathway was validated for the analysis of pure substances and of complex mixtures. Further, the cell's capability to detect genotoxins correctly with and without an exogenous metabolizing system, namely rat liver S9, was assessed.

RESULTS

The assay proved to have a high toxicological sensitivity (87.5%) and specificity (94%). Further, the endogenous metabolizing system of the HepG2 cells was able to detect some genotoxins, which are known to depend on an enzymatic system. When complex mixtures were added this did not lead to any adverse effects concerning the assays performance and cytotoxicity was not an issue.

DISCUSSION

The HepGentox proved to have a high toxicological sensitivity and specificity for the tested substances, with similar or even lower lowest effective concentration (LEC) values, compared to other regulatory mammalian assays. This combines some important aspects in one test system, while also being less time and material consuming and covering several genotoxicity endpoints. As the assay performs well with and without an exogenous metabolizing system, no animal liver fractions have to be used, which application is discussed controversially and is considered to be expensive and laborious in sample testing. Because of this, the HepGentox is suitable for a cost-efficient first screening approach to obtain important information with human cells for further approaches, with a relatively fast and easy method. Therefore, the HepGentox is a promising assay to detect genotoxic substances correctly in complex mixtures even at low concentrations, with the potential for a high throughput application. In a nutshell, as part of an in vitro bioassay test battery, this assay could provide valuable information for complex mixtures.

Environmental and economic assessment of food-packaging systems with a focus on food waste. Case study on tomato ketchup

In this paper, a sustainability evaluation method for food-packaging systems is proposed. First, food waste due to poor emptiability was determined. Then, these quantities were included in life cycle assessments (LCA) and life cycle costing (value added, VA) of the products. Finally, LCA and VA results were combined using multi-criteria decision analysis, Technique for Order by Similarity to Ideal Solution (TOPSIS), in order to identify the most sustainable food packaging system. As a case study, four different ketchup products were examined. For ketchup in polypropylene bottles, FLW resulting from poor emptiability ranged from 13.12% (±2.05) to 28.80% (±3.30) respectively, while this was only 3.85% (±0.41) for ketchup packaged in glass. After integrating the emptiability results into life cycle assessments, this resulted in greenhouse gas emissions of 5.66 to 9.16 kg CO_2eq per 3.80 kg consumed ketchup, the average consumption per capita in Austria. Importantly, poor emptiability of the examined products led to greater environmental impacts than the associated packaging. While greater product loss also pushes up the costs for consumers, it contributes to more value added to the economic system, which is in stark contrast to the goal of decoupling the economy from resource consumption.

Evaluation of the Suitability of Mammalian In Vitro Assays to Assess the Genotoxic Potential of Food Contact Materials

Background: Non-targeted screening of food contact materials (FCM) for non-intentionally added substances (NIAS) reveals a great number of unknown and unidentified substances present at low concentrations. In the absence of toxicological data, the application of the threshold of toxicological concern (TTC) or of EU Regulation 10/2011 requires methods able to fulfill safety threshold criteria. In this review, mammalian in vitro genotoxicity assays are analyzed for their ability to detect DNA-damaging substances at limits of biological detection (LOBD) corresponding to the appropriate safety thresholds. Results: The ability of the assays to detect genotoxic effects varies greatly between substance classes. Especially for direct-acting mutagens, the assays lacked the ability to detect most DNA reactive substances below the threshold of 10 ppb, making them unsuitable to pick up potential genotoxicants present in FCM migrates. However, suitability for the detection of chromosomal damage or investigation of other modes of action makes them a complementary tool as part of a standard test battery aimed at giving additional information to ensure safety. Conclusion: improvements are necessary to comply with regulatory thresholds to consider mammalian genotoxicity in vitro assays to assess FCM safety.

Value and limitation of in vitro bioassays to support the application of the threshold of toxicological concern to prioritise unidentified chemicals in food contact materials

Some of the chemicals in materials used for packaging food may leak into the food, resulting in human exposure. These include so-called Non-intentionally Added Substances (NIAS), many of them being unidentified and toxicologically uncharacterized. This raises the question of how to address their safety. An approach consisting of identification and toxicologically testing all of them appears neither feasible nor necessary. Instead, it has been proposed to use the threshold of toxicological concern (TTC) Cramer class III to prioritise unknown NIAS on which further safety investigations should focus. Use of the Cramer class III TTC for this purpose would be appropriate if amongst others sufficient evidence were available that the unknown chemicals were not acetylcholinesterase inhibitors or direct DNA-reactive mutagens. While knowledge of the material and analytical chemistry may efficiently address the first concern, the second could not be addressed in this way. An alternative would be use of a bioassay capable of detecting DNA-reactive mutagens at very low levels. No fully satisfactory bioassay was identified. The Ames test appeared the most suitable since it specifically detects DNA-reactive mutagens and the limit of biological detection of highly potent genotoxic carcinogens is low. It is proposed that for a specific migrate, the evidence for absence of mutagenicity based on the Ames test, together with analytical chemistry and information on packaging manufacture could allow application of the Cramer class III TTC to prioritise unknown NIAS. Recommendations, as well as research proposals, have been developed on sample preparation and bioassay improvement with the ultimate aim of improving limits of biological detection of mutagens. Although research is still necessary, the proposed approach should bring significant benefits over the current practices used for safety evaluation of food contact materials.

Technical emptiability of dairy product packaging and its environmental implications in Austria

BACKGROUND

Food waste is a major ecological concern around the globe. While the main function of packaging is to contain and protect food, it may also lead to food waste if residues remain in a package after emptying. Such residues could be attributed to wasteful behavior of consumers, but also to properties of packaging (e.g., geometry, surface tension) and food (e.g., surface tension, viscosity).

METHODS

In this study, the technical emptiability (ability of packaging to be emptied entirely) of 36 dairy products is analyzed. Firstly, the amount of food residues in packaging after emptying at room and refrigerator temperature was weighed and set in relation to the original filling quantity. Secondly, streamlined life cycle assessments (LCAs) based on the Product Environmental Footprint guidance with a functional unit of "one kg of consumed dairy product at room or refrigerator temperature in the home of the consumer" are conducted. Finally, technical emptiability was included in the streamlined LCA and attributed to the primary packaging in order to evaluate its environmental impact.

RESULTS

Technical emptiability for both temperatures combined was found to be between 0.25% (±0.11) and 5.79% (±0.43) for the analyzed dairy products. While there were differences in emptiability results of the same product and different temperatures, no significant trend (p = 0.94) between emptiability and temperature could be observed. Liquid yogurt, cream, and buttermilk in beverage cartons and plastic bottles yielded the highest amounts, while milk in beverage cartons and glass bottles yielded the lowest amounts regarding food residues. Looking at global warming potential, poor technical emptiability of cream in a beverage carton leads to even higher environmental impacts than the production and waste management of its packaging.

DISCUSSION

The streamlined LCA results show that food residues can contribute substantially to the footprint of packaging and can have similar or even higher environmental impacts than packaging production and waste management. Yet, emptiability is remarkably under-researched to this day. Future studies should further develop the methods presented in this paper, while LCA analysts should include technical emptiability when assessing the sustainability of packaging, particularly for those containing resource-intensive goods.

Mutagenicity assessment of food contact material migrates with the Ames MPF assay

A major challenge in the safety assessment of food contact materials (FCM) is the evaluation of unknown non-intentionally added substances (NIAS). Even though consumer exposure levels may be quantitatively low, these substances are considered to be of high toxicological concern if they act as DNA reactive mutagens. From a safety assessment perspective, it is therefore important to detect their presence in FCM migrates. The present study applied the Ames MPF assay to assess the mutagenicity of migrates obtained from 30 food contact material samples out of 3 categories: plastics, composite materials and coatings. As a food simulant, 95% ethanol (EtOH) had a superior performance to less volatile simulants when evaluating recovery rates of representative model substances in different volatility categories. To monitor possible interference of the FCM matrix with Ames MPF results, migrates were spiked with reference substances and recovery rates were established. Out of 30 samples tested, two caused significant inhibition of revertant formation in the presence of the spiking control. Overall detection limits of the applied test method were estimated by determination of the lowest effective concentrations (LEC) for 10 Ames-positive substances. Even though the current limits of detection are not sufficient to entirely fulfil regulatory and safety requirements, three out of 30 FCMs showed evidence of dose-dependent effects in the Ames MPF assay. Overall, the data obtained supported the relevance of testing FCM migrates for DNA reactive contaminants and showed the value of the Ames MPF assay for the safety assessment of FCMs.

Suitability of the Ames test to characterise genotoxicity of food contact material migrates

Non-intentionally added substances (NIAS) are chemical impurities which can migrate from packaging materials (FCM) into food. Safety assessment of NIAS is required by European law, but currently there is no comprehensive testing strategy available. In this context, one key element is to get insight on the potential presence of genotoxic NIAS in FCM migrates. This raises questions about the limit at which genotoxins can be detected in complex mixtures such as FCM migrates, and if such limits of detection (LOD) would be compatible with safety. In this context, the present review assesses the suitability of the Ames assay to address genotoxicity of FCM migrates. Lowest effective concentrations of packaging-related and other chemicals in test media were retrieved from scientific literature and used as surrogates of LODs to be benchmarked against a value of 0.01 mg kg^-1 (10 ppb) in migrates. This is a pragmatic threshold used in FCM safety evaluation to prioritise substances requiring proper identification and risk assessment. The analysis of the data shows that only potent genotoxins can theoretically be detectable at a level of 0.01 mg kg^-1 in migrates or food. Only a minority (10%) of genotoxic chemicals reported to be associated with FCMs could be picked up at a level of 0.01 mg kg^-1 or lower. Overall, this review shows that the Ames test in its present form cannot be used as standalone method for evaluating the genotoxic potential of FCM migrates, but must be used together with other information from analytical chemistry and FCM manufacturing.

Characterization of estrogen and androgen activity of food contact materials by different in vitro bioassays (YES, YAS, ERα and AR CALUX) and chromatographic analysis (GC-MS, HPLC-MS)

Endocrine active substances (EAS) show structural similarities to natural hormones and are suspected to affect the human endocrine system by inducing hormone dependent effects. Recent studies with in vitro tests suggest that EAS can leach from packaging into food and may therefore pose a risk to human health. Sample migrates from food contact materials were tested for estrogen and androgen agonists and antagonists with different commonly used in vitro tests. Additionally, chemical trace analysis by GC-MS and HPLC-MS was used to identify potential hormone active substances in sample migrates. A GC-MS method to screen migrates for 29 known or potential endocrine active substances was established and validated. Samples were migrated according to EC 10/2011, concentrated by solid phase extraction and tested with estrogen and androgen responsive reporter gene assays based on yeast cells (YES and YAS) or human osteoblast cells (ERα and AR CALUX). A high level of agreement between the different bioassays could be observed by screening for estrogen agonists. Four out of 18 samples tested showed an estrogen activity in a similar range in both, YES and ERα CALUX. Two more samples tested positive in ERα CALUX due to the lower limits of detection in this assay. Androgen agonists could not be detected in any of the tested samples, neither with YAS nor with AR CALUX. When testing for antagonists, significant differences between yeast and human cell-based bioassays were noticed. Using YES and YAS many samples showed a strong antagonistic activity which was not observed using human cell-based CALUX assays. By GC-MS, some known or supposed EAS were identified in sample migrates that showed a biological activity in the in vitro tests. However, no firm conclusions about the sources of the observed hormone activity could be obtained from the chemical results.

Determination of microbial contamination of plastic cups for dairy products and utilization of electron beam treatment for sterilization

Packaging materials are often considered a critical control point in HACCP systems of food companies. Methods for the determination of the microbial contamination rate of plastic cups, especially for dairy products, must reliably detect single moulds, yeasts or coliforms. In this study, a comparison of a specially adapted coating method, impedance method, direct inoculation and membrane filter technique was carried out to determine contamination with yeasts, moulds, coliforms and total bacterial counts using the appropriate agar in each case. The coating method is recommended for determining yeasts, moulds and coliforms as it allows the localization of the microorganisms as well as the determination of single microorganisms. For total bacterial count, a direct inoculation technique is proposed. The employing of simple measures in the production and during transport of packaging materials, such as dust-prevention or tight sealing in polyethylene bags, heavily reduces microbial contamination rates of packaging material. To reduce contamination rates further, electron beam irradiation was applied: plastic cups sealed in polyethylene bags were treated with 4-5 kGy, a dose that already leads to sterile polystyrene and polypropylene cups without influencing mechanical characteristics of the packaging material.

Nonaqueous capillary electrophoretic separation of basic enantiomers using heptakis(2,3-dimethyl-6-sulfato)-beta-cyclodextrin

The enantiomers of 40 basic analytes, mostly pharmaceuticals, were separated by nonaqueous capillary electrophoresis in acidic methanol background electrolytes using the sodium salt of heptakis(2,3-dimethyl-6-sulfato)-beta-cyclodextrin (HDMS-beta-CD). The effective mobilities, separation selectivities, and peak resolution values were determined as a function of the HDMS-beta-CD concentration in the 0-40 mM range and were found to follow the theoretical predictions of the charged resolving agent migration model (CHARM model). Fast, efficient enantiomer separations were achieved for a large number of both very hydrophobic and hydrophilic weak bases.

Statistics of RNA melting kinetics

We present and study the behavior of a simple kinetic model for the melting of RNA secondary structures, given that those structures are known. The model is then used as a map that assigns structure dependent overall rate constants of melting (or refolding) to a sequence. This induces a "landscape" of reaction rates, or activation energies, over the space of sequences with fixed length. We study the distribution and the correlation structure of these activation energies.

Expression of intercellular adhesion molecule-1 (ICAM-1) on human thyroid cells lines correlated with their binding of lymphoblasts

We have investigated the expression of intercellular adhesion molecule-1 (ICAM-1) by novel functional human thyroid cell lines (designated SGHTL). ICAM-1 is constitutively expressed and it is rapidly upregulated in response to each of the recombinant cytokines: gamma-interferon, interleukin-1 and tumour necrosis factor. This contrasts with the more slowly increased expression of major histocompatibility complex (MHC) class II antigens in response to gamma-interferon alone. We have also demonstrated binding of activated lymphocytes to SGHTL cells: this interaction is increased following treatment with these cytokines and is inhibited by monoclonal antibodies directed against ICAM-1 or lymphocyte function-associated antigen-1 (LFA-1) but not by antibodies against CD2 or MHC class II antigens. Hence, we conclude that the binding of lymphoblasts to human thyroid cells involves an LFA-1- and ICAM-1-dependent pathway as well as other basal and cytokine-inducible pathway(s). These do not appear to involve MHC class II antigens, CD2 or an LFA-1 ligand other than ICAM-1.