Multilayer Plastic Research Articles

Safety by design of printed multilayer materials intended for food packaging

ABSTRACTPrinting inks are commonly used in multilayer plastics materials used for food packaging, and compounds present in inks can migrate to the food either by diffusion through the multilayers or because of set-off phenomena. To avoid this problem, the right design of the packaging is crucial. This paper studies the safety by design of multilayer materials. First, the migration from four different multilayers manufactured using polyethylene terephthalate (PET), aluminium (Al) and polyethylene (PE) was determined. The structural differences among materials such as the presence of inks or lacquer coatings as well as the differences in layers position allowed the study of a safety-by-design approach. Sixty-nine different compounds were detected and identified; 49 of them were not included in the positive list of Regulation EU/10/2011 or in Swiss legislation and 15 belong to Cramer class III, which means that they have a theoretical high toxicity. Some of the compounds related to ink composition were pyrene, a compound commercially used to make dyes and dye precursors and the antioxidant Irganox 1300. The application of external lacquers decreased the concentration of some migrants but also brought the potential for new migrants coming from its composition. A final risk assessment of the material allowed evaluating food safety for different food simulants and confirm it.

Development of anti-insect multilayered films for brown rice packaging that prevent Plodia interpunctella infestation

The aim of this study was to develop a multilayered insect-proof film that prevents contamination with Plodia interpunctella (Hübner; Lepidoptera: Pyralidae) insect larvae. The anti-insect activities of five essential oils (EOs), allyl disulfide (AD), and allyl mercaptan isolated from garlic and onion, respectively, were evaluated. Subsequently, fumigation insecticidal assays were performed to identify the anti-insect agents, their optimal concentrations. Garlic, onion EOs and their compounds were chosen as efficient anti-insect agents for application to rice flour-based multilayered plastic films. Penetration tests were then used to evaluate the ability of multilayered films to resist invasion by P. interpunctella larvae. Films containing 5% AD (AD-5) had the strongest resistance to penetration by insects. Thus, AD-5 was applied to brown rice packaging to measure protection from insects and to assess sensory properties. In these analyses, AD-5 showed insect-proofing effects and no undesirable changes to the sensory properties of the rice after cooking. Hence, this novel multilayer film could be used as an active packaging material with effective anti-insect activities and desirable physical properties.

Finite element analysis of cavity nucleation on adhesive surface in peel tests of multilayer plastic film

Finite element analysis of cavity nucleation on adhesive surface in peel tests of multilayer plastic film

Nano selenium as antioxidant agent in a multilayer food packaging material.

Selenium nanoparticles (SeNPs) were incorporated in a flexible multilayer plastic material using a water-base adhesive as vehicle for SeNPs. The antioxidant performance of the original solutions containing spherical SeNPs of 50-60nm diameter, the adhesive containing these SeNPs, and the final multilayer plastic material to be used as food packaging were quantitatively measured. The radical scavenging capacity due to SeNPs was quantified by a free radical assay developed in the laboratory and by the diphenyl-1-picrylhydrazyl (DPPH) method. DPPH was not efficient to measure the scavenging capacity in the multilayer when the free radical scavenger is not in the surface in contact with it. Several multilayer laminated structures composed by [PET (20m)-adhesive-LDPE (with variable thickness from 35 to 90μm)] were prepared and measured, demonstrating for the first time that free radicals derived from oxygen (OH·, O2·, and O2H) cross the PE layer and arrive at the adhesive. SeNPs remain as such after manufacture and the final laminate is stable after 3months of storage. The antioxidant multilayer is a non-migrating efficient free radical scavenger, able to protect the packaged product versus oxidation and extending the shelf life without being in direct contact with the product. Migration tests of both Se and SeNPs to simulants and hazelnuts demonstrated the non-migrating performance of this new active packaging. Graphical abstract ᅟ.

Towards human-controlled, real-time shape sensing based flexible needle steering for MRI-guided percutaneous therapies.

Accurate needle placement into soft tissue is essential to percutaneous prostate cancer diagnosis and treatment procedures. This paper discusses the steering of a 20 gauge (G) FBG-integrated needle with three sets of Fiber Bragg Grating (FBG) sensors. A fourth-order polynomial shape reconstruction method is introduced and compared with previous approaches. To control the needle, a bicycle model based navigation method is developed to provide visual guidance lines for clinicians. A real-time model updating method is proposed for needle steering inside inhomogeneous tissue. A series of experiments were performed to evaluate the proposed needle shape reconstruction, visual guidance and real-time model updating methods. Targeting experiments were performed in soft plastic phantoms and in vitro tissues with insertion depths ranging between 90 and 120 mm. Average targeting errors calculated based upon the acquired camera images were 0.40 ± 0.35 mm in homogeneous plastic phantoms, 0.61 ± 0.45 mm in multilayer plastic phantoms and 0.69 ± 0.25 mm in ex vivo tissue. Results endorse the feasibility and accuracy of the needle shape reconstruction and visual guidance methods developed in this work. The approach implemented for the multilayer phantom study could facilitate accurate needle placement efforts in real inhomogeneous tissues. Copyright © 2016 John Wiley & Sons, Ltd.

Recyclability of PET/WPI/PE Multilayer Films by Removal of Whey Protein Isolate-Based Coatings with Enzymatic Detergents.

Multilayer plastic films provide a range of properties, which cannot be obtained from monolayer films but, at present, their recyclability is an open issue and should be improved. Research to date has shown the possibility of using whey protein as a layer material with the property of acting as an excellent barrier against oxygen and moisture, replacing petrochemical non-recyclable materials. The innovative approach of the present research was to achieve the recyclability of the substrate films by separating them, with a simple process compatible with industrial procedures, in order to promote recycling processes leading to obtain high value products that will beneficially impact the packaging and food industries. Hence, polyethyleneterephthalate (PET)/polyethylene (PE) multi-layer film was prepared based on PET coated with a whey protein layer, and then the previous structure was laminated with PE. Whey proteins, constituting the coating, can be degraded by enzymes so that the coating films can be washed off from the plastic substrate layer. Enzyme types, dosage, time, and temperature optima, which are compatible with procedures adopted in industrial waste recycling, were determined for a highly-efficient process. The washing of samples based on PET/whey and PET/whey/PE were efficient when performed with enzymatic detergent containing protease enzymes, as an alternative to conventional detergents used in recycling facilities. Different types of enzymatic detergents tested presented positive results in removing the protein layer from the PET substrate and from the PET/whey/PE multilayer films at room temperature. These results attested to the possibility of organizing the pre-treatment of the whey-based multilayer film by washing with different available commercial enzymatic detergents in order to separate PET and PE, thus allowing a better recycling of the two different polymers. Mechanical properties of the plastic substrate, such as stress at yield, stress and elongation at break, evaluated by tensile testing on films before and after cleaning, were are not significantly affected by washing with enzymatic detergents.

Sensory methods and electronic nose as innovative tools for the evaluation of the aroma transfer properties of food plastic bags

Despite the key role of the sensory quality for food acceptance, the aroma transfer properties of food packaging materials have not yet been studied using sensory approaches. This research investigated the suitability of sensory and electronic nose methods to evaluate the aroma transfer properties of plastic materials that come in contact with food. Four (W, X, Y, and Z) commercial freezer bags (polyethylene) for domestic uses were compared. The degree of the aroma transfer through the materials was estimated as the sensory contamination of an odor absorber food (bread) by an odor releaser food (onion), separated by the bags and stored under frozen conditions. Bread samples were analyzed by means of an electronic nose, and 42 assessors used three different sensory methods (triangle, scoring, and partial sorted Napping tests). From the triangle test, none of the plastic bags acted as a complete aroma barrier, showing a sensory contamination of bread stored in all four materials. Partial sorting Napping results clearly described the sensory contamination of bread as “onion flavor”, due to the aroma transfer from the odor releaser food to the odor absorber food through the plastic bag. Scoring tests showed significant (p<0.0001) differences of aroma transfer properties among the plastic bags, revealing the highest aroma permeation for W (3.1±0.1), the lowest aroma transfer for X and Y (2.0±0.1), and intermediate aroma transfer properties for Z (2.6±0.1). Electronic nose data were in good agreement with the sensory responses, and a high correlation with the scoring data was observed (R2=0.988). The presented approaches had suitable results to provide meaningful information on the aroma transfer properties of freezer plastic bags, and could advantageously be applied in the future for analyzing other finished food containers (e.g. plastic trays, boxes, etc.) or packaging materials of a different nature (multilayer plastic films, biodegradable materials, composites, etc.).

Effect of storage parameters on freeze‐dried kefir grains

The purpose of this study was to use freeze‐drying to preserve microbial activity while extending the shelf life of kefir grains and to determine the best storage temperature. Freeze‐dried kefir grains were lyophilised and were later stored in a multilayer plastic film with a moisture barrier for 90 days at varying temperatures. Microbial activity continued until the 60th day of storage at 4 °C. PCR analysis was performed to determine Lactobacillus kefiranofaciens as an indicator kefir micro‐organism. It was concluded that the conservation of kefir grains by freeze‐drying protects the natural embedded microbiota; therefore, both the shelf life of kefir grains and the consumption of natural kefir increase.

Design and acoustical performance investigation of sound absorption structure based on plastic micro-capillary films

Based on its constituting parallel micro-capillaries, the sound absorption behavior of multi-layer plastic micro-capillary film (MCF) structure has been investigated. The effects of micro-capillary diameter, perforation rate and perforation diameter on the sound absorption performance of the multi-layer MCF structures were studied using the standing wave tube method. It was demonstrated that the multi-layer MCFs had good sound absorption especially at low frequencies around the resonant frequency. The mechanical property of the MCF samples was measured by a strength tester and results demonstrated this sound absorption structures had stable mechanical behavior. Compared to two traditional sound absorption materials (perforated panel and porous material), the sound absorption coefficients of the MCF samples are comparable and competitive to them. Therefore the novel multi-layer MCFs, which are easy-to-manufacture and cost-effective, have promising applications in the field of sound absorption.

Reliable liquid chromatography-mass spectrometry method for investigation of primary aromatic amines migration from food packaging and during industrial curing of multilayer plastic laminates.

Primary aromatic amines (PAAs) can migrate from packaging into food from different sources such as polyurethanic adhesives used for the manufacture of multilayer films, which may contain residual aromatic isocyanates, or recycled paperboard, because of the presence of azo dyes in the printed paper massively used in the recycling process. In the present work, a reliable analytical method, exploiting a conventional high-performance liquid chromatography-(selected ion monitoring)-mass spectrometry system, for PAAs compliance assessment in food contact materials was developed as an effective alternative to the current standard spectrophotometric one, moving in this way from the screening to the accurate and selective quantitation perspective for the analysis of PAAs both in aqueous and acidic food simulants. The main validation parameters were verified achieving very satisfactory results in terms of linearity range, limit of detection (ranging from 0.1 to 1.0 µg kg(-1)) and quantitation (ranging from 0.1 to 3.6 µg kg(-1)), repeatability and accuracy. Suitability of the method was demonstrated for a wide range of commercial samples, chosen among different producers of the most common used food packaging plastic and paperboard categories and then analyzed to assess the risk related to PAAs migration. Finally, the method was also successfully exploited to monitor the evolution of potential PAAs migration during the industrial curing process of multilayer plastic laminates, prior to their release for delivery to the food industry end user.

Compounds from multilayer plastic bags cause reproductive failures in artificial insemination.

High levels of reproductive failure were detected in some Spanish sow farms in the Spring of 2010. Regular returns to estrus and variable reductions in litter size were observed. The problem started suddenly and did not appear to be related to the quality of the ejaculates, disease, alterations of body condition or any other apparent reasons. Subsequent studies determined that the problem was the origin of the plastic bags used for semen storage. Chemical analysis of the suspicious bags identified unexpected compounds such as BADGE, a cyclic lactone and an unknown phthalate that leached into the semen at concentrations of 0.2 to 2.5 mg/L. Spermatozoa preserved in these bags passed all of the routine quality control tests, and no differences were observed between storage in the control and suspicious bags (p > 0.05). In vitro fecundation tests and endocrine profiler panel analysis (EPP) did not show any alterations, whereas the in vivo tests confirmed the described failure. This is the first described relationship between reproductive failure and toxic compounds released from plastic bags.

Scientific Opinion on the safety assessment of the substances, kaolin and polyacrylic acid, sodium salt, for use in food contact materials

This scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavorings and Processing Aids (CEF) deals with the safety assessment of kaolin which is used in a combination with polyacrylic acid, sodium salt and is incorporated in a gas barrier layer of ethylene-vinyl alcohol (EVOH) copolymer. The EVOH copolymer is used as an inner layer in multi-layer food contact materials. Morphological studies show stacks of kaolin clay platelets of different sizes dispersed in the EVOH and some of these platelets are below 100 nm in the thickness dimension. Nevertheless, exfoliation into individual platelets does not occur for kaolin as confirmed by WAXS. No migration of the kaolin particles from the EVOH layer was shown. There was no detectable migration of aluminium or magnesium (inorganic constituents of kaolin) from a typical multi-layer plastic material, with detection limits of 0.07 mg/kg and up to 2.2 mg/kg, respectively. These values indicate that migration of these inorganic components is not expected to be significant. Migration of polyacrylic acid sodium salt is not expected to exceed the SML of 6 mg/kg foodstuffs at the conditions of use foreseen. Therefore, the CEF panel concluded that the substance kaolin in the form of particles with a thickness less than 100 nm does not raise a safety concern for the consumer when incorporated up to 12 % in EVOH copolymer. This material is used as an inner layer of a plastic multi-layer structure, in contact with foods and beverages stored at room temperature up to 6 months. The EVOH inner layer containing the particles should be used behind a functional barrier that prevents migration of kaolin particles into the food.

High-performance oxygen barrier inorganic–organic coating for polymeric substrates

Aqueous-based inorganic–organic hybrid coating materials comprising self-assembled silica nanophase (SNAP) particles and the sodium salt of 9,10-anthraquinone-2,6-disulfonate (AQDS), an oxygen-scavenging precursor molecule, were coated onto PET films under ambient laboratory conditions using a spiral-bar coating technique. Active SNAP-based coatings containing 0.08% w/w AQDS displayed an oxygen transmission rate of 0.04±0.01cm3milm−2day−1atm−1; an improvement in oxygen barrier by an order of magnitude compared with comparable coatings produced using dip-coating. The spiral-bar coating technique also provided other important technical advantages over the previously used dip-coating method, including a reduction in the AQDS concentration required in the coating solution by almost an order of magnitude. The oxygen barrier performance provided by these single-layer active SNAP-based coatings approaches that provided by other far more sophisticated multi-layer plastic barrier materials produced using vacuum-deposition methods.

Evaluation of Physicochemical, Microbiological and Sensory Stability of Frozen Stored Vacuum-Packed Lamb Meat

Nowadays, lamb meat represents only 7% of all meat produced in the world. In recent years the demand for standardized lamb meat cuts has been considered of great importance and the marketing occurs predominantly in the form of frozen cuts. Herewith, the main of this work was to evaluate the stability and safety of lamb meat during frozen storage. Meats were vacuum packed in high barrier multilayer plastic films and stored during 12 mon at (−18±1)°C. The meat stability was assessed by physical and chemical (lipid oxidation, objective color, pH value, cooking losses and instrumental texture), microbiological (total count of psychrotrophic, coliform count at 45°C, coagulase-positive staphylococci and the presence of Salmonella) and sensory analysis (acceptance test and visual evaluation). The vacuum packed lamb meat remained stable as to most physical and chemical indexes. Microbiological indexes showed good stability throughout the storage period according to Brazilian legislation standards to pathogenic microorganisms. Although a significant reduction in tenderness (shear force increase from 3 to 8 kg), it showed a good sensorial acceptance for all attributes tested, including texture, with scores of around 7 (like moderately) during the 12 mon of storage. Therefore, it can be concluded that, under the conditions applied in this study, lamb meat presents a shelf life of at least 12 mon when stored at −18°C.

Scientific Opinion on the safety evaluation of a time‐temperature indicator system, based on Carnobacterium maltaromaticum and acid fuchsin for use in food contact materials

This scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety evaluation of a system based on Carnobacterium maltaromaticum and a colour change indicator, acid fuchsin (CAS Number 3244-88-0, FCM Substance No 01033), used as a time-temperature indicator on the packaging of chilled food. The micro-organism, the indicator and a nutritive medium gel are incorporated in a multilayer plastic sachet glued onto the outer layer of the food package. All the substances constituting the system, with the exception of acid fuchsin, are authorised as food additives, food colorants or novel food ingredients, or are an enzymatic digest of edible protein sources and yeast edible extract. Specific migration of acid fuchsin was estimated to be less than 7 × 10-9 mg/kg food. Acid fuchsin elicited a positive response in a bacterial gene mutation assay and a negative response in an in vitro micronucleus assay. Given the lack of in vivo studies, the genotoxicity potential of acid fuchsin cannot be ruled out. However, the Panel noted that the layer of the plastic sachet in contact with food contact articles behaves as a barrier which prevents any release of its content (including acid fuchsin), and that the sachet is stuck onto the outer layer of the packaging, hence is not in contact with the food. Thus no exposure to the substances constituting the system from the consumption of the packed food is expected under the intended conditions of use. Therefore, the Panel concluded that the substances of the intelligent system, C. maltaromaticum and acid fuchsin, do not raise a safety concern for the consumer when used in a plastic sachet which prevents any migration from the system into food and which is stuck onto the outer layer of the packaging of chilled food.

STUDY ON QUALITY CHANGES OF LEMEA DURING STORAGE IN VARIOUS TYPES OF TEMPERATURE AND PACKAGING MATERIALS

Lemea is a traditional food from Rejang tribes that needs improvement in packaging so that the product can compete with other packaged foods. A study to get the proper packaging to maintain lemea’s quality using various types of packaging materials and storage temperatures is necessary to be conducted. The objective of this study is to examine effect of various types of packaging materials and storage temperature on quality changes of lemea. The study designed using CRD with 2 factors and 3 replications. Type of packaging material used in this research is LDPE plastic with a thickness of 0:01 mm, OPP / PP multilayer plastic with a thickness of 0.05 mm and PETE plastic bottles with a thickness of 1:25 mm; storage temperature used is room temperature at 27-32 °C and refrigerator temperature at 12-15 °C. Parameters measured were changes in water content, pH value, the number of colonies of microbes and organoleptic (color, scent, shape and overall acceptance attributes of lemea) on lemea that stored for 28 days with the observation point on day 7, 14, 21 and 28. Various of packaging materials of lemea are LDPE plastic, OPP / PP multilayer plastic, and PETE plastic bottles showed significant effect on moisture content, pH, TPC, and organoleptic in room temperature storage at 27-32 °C but it had no significant effect in the refrigerator temperature storage at 12-15 °C. The difference in storage temperature affects the occurrence of deviation or alteration of lemea quality.

STUDY ON QUALITY CHANGES OF LEMEA DURING STORAGE IN VARIOUS TYPES OF TEMPERATURE AND PACKAGING MATERIALS

Lemea is a traditional food from Rejang tribes that needs improvement in packaging so that the product can compete with other packaged foods. A study to get the proper packaging to maintain lemea’s quality using various types of packaging materials and storage temperatures is necessary to be conducted. The objective of this study is to examine effect of various types of packaging materials and storage temperature on quality changes of lemea. The study designed using CRD with 2 factors and 3 replications. Type of packaging material used in this research is LDPE plastic with a thickness of 0:01 mm, OPP / PP multilayer plastic with a thickness of 0.05 mm and PETE plastic bottles with a thickness of 1:25 mm; storage temperature used is room temperature at 27-32 °C and refrigerator temperature at 12-15 °C. Parameters measured were changes in water content, pH value, the number of colonies of microbes and organoleptic (color, scent, shape and overall acceptance attributes of lemea) on lemea that stored for 28 days with the observation point on day 7, 14, 21 and 28. Various of packaging materials of lemea are LDPE plastic, OPP / PP multilayer plastic, and PETE plastic bottles showed significant effect on moisture content, pH, TPC, and organoleptic in room temperature storage at 27-32 °C but it had no significant effect in the refrigerator temperature storage at 12-15 °C. The difference in storage temperature affects the occurrence of deviation or alteration of lemea quality.

Laminated film composites of multilayered plastic film and inorganic polymer binder as an alternative to transparent and hard glass

Laminated film composite was fabricated by stacking the surface-modified poly(ethylene terephthalate) films using the initiated chemical vapor deposition (iCVD) method, with a ultraviolet (UV)-curable methacrylate-polyhedral oligomeric silsesquioxane (POSS) inorganic polymer interlayer binder to develop an alternative glass material. The 11-layered PET film/POSS composites were consolidated by UV exposure, and it increased modulus and maintained transmittance and haze.

Purity and Stability of Online-Prepared Hemodiafiltration Fluid after Storage

Background/Aims: Previous studies have suggested that online hemodiafiltration (OL-HDF) fluid can be used as dialysate for continuous renal replacement therapies, and thus HDF costs can be reduced. The aims of this study were to determine the purity of OL-HDF fluid and to verify the stability of the electrolyte composition and acid-base balance during its storage. Methods: OL-HDF fluid was collected in 70 individual bags and stored for up to 7 days. The following tests were performed daily in 10 bags: natural visible precipitation (macrocrystallization), sample collection for chemical analysis and fluid culture, limulus amebocyte lysate endotoxin test, standard culture of NALGENE® filters after passing of the fluid, and molecular analysis of bacterial DNA. Results: The values of pH and pCO₂ showed a significant change starting at 24 h (p < 0.001); after 72 h, their values were beyond the measurable range. Coefficient of variation for pCO₂ was as high as 25.7%. Electrolyte composition (Na⁺, K⁺, Cl^–, Ca²⁺ and glucose) showed a statistically significant difference over time (p < 0.05); however, their coefficients of variation were low (1.7, 1.4, 0.6, 2.3 and 0.9%, respectively), which might not be considered clinically significant. Negative results were obtained at all points by fluid and filter cultures, endotoxin test and molecular analysis. No macrocrystallization was observed at any time point. Conclusions: We demonstrate the microbiological purity of OL-HDF fluid stored for up to 7 days. The electrolyte composition was stable, except for a relevant change in p<smlcap>CO</smlcap>₂ and consequently in pH (first noted at 24 h), emphasizing the need to reassess the acid-base balance in multilayer plastic bags in future studies.

Ambiguity-free spectral-domain optical coherence tomography for determining the layer thicknesses in fluttering foils in real time

When imaging thick or axially moving samples with spectral-domain optical coherence tomography, mirror terms overlapping with the signals of interest can cause ambiguities. These ambiguities complicate the analysis of the imaged structures and are especially troublesome for processes in which sample parameters have to be monitored in a fully automated way and in real time. In this study we focus on a purely hardware-based approach to overcome this problem. The method is based on shifting and shaping the sensitivity profile by spatially separating the two interferometer beams on the diffraction grating in the spectrometer. The usefulness of the approach, including its robustness against axial sample movements, is demonstrated for a multi-layered plastic foil structure. The proposed method neither requires additional data post-processing nor a significant increase in cost or complexity of the experimental design. It is therefore well suited for in-line quality control purposes.