Physical and chemical modifications of cellulose fibers for food packaging applications

Cellulose - Cellulose fibers have gained considerable interest for use as gas barriers and reinforcing fillers in food packaging materials because of their interesting properties, including...     

Thermal stability of the PBAT biofilms with cellulose nanostructures/essential oils for active packaging

The primary objective of this study is to evaluate the thermal stability of the active films with the cellulose nanostructure (CNS, 5?mass%) treated with encapsulated essential oils (EOs), eugenol and linalool. CNS untreated and treated were incorporated in the poly(butylene adipate-co-terephthalate) (PBAT) polymer matrix prepared by casting. In this study, all samples were characterized by FTIR, DRX, TG, DSC and SEM, elucidating the contribution of each component in the final films. CNS untreated and treated with EOs were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA), confirming the interaction between these components. The active biofilms were analyzed by TGA and DSC analyses (differential scanning calorimetry), confirming that their thermal stability was maintained similar to the neat PBAT film, without loss of properties. The CI (crystallinity index, %) of the polymeric films was calculated from heat fusion (ΔH) values, indicating that the incorporation of the nanostructures into the PBAT matrix increases the crystallinity of the biofilms, from 11.5 (neat PBAT) to 13.8% (PBAT/CNS-E), acting as a nucleating agent in the polymeric matrix. The presence of the EOs did not decrease the CNS stability, as well of the biocomposite films. Moreover, the thermal analysis confirmed that the EO was well involved by the CNS, before and after the incorporation in the PBAT polymer, as observed in the SEM images.

     

Development of new polyolefin films with nanoclays for application in food packaging

Nanomaterials have been demonstrated to possess novel characteristics that can be applied in developing new packaging with better properties than packaging produced with micromaterials. Such developments include the production of packaging with improved barrier properties, which applied to the food industry will extend the shelf life of a food, thereby expanding its marketing potential. The present study entailed the optimization of experimental variables (pressure, temperature, processing time, feed position, etc.) involved in the elaboration of polypropylene and polyethylene films with nanoparticles, to obtain a film with good exfoliation, barrier and mechanical properties. SEM, TEM and XRD were also evaluated as tools for determining the degree of exfoliation of nanoparticles. Optimization of the technology involved in production of an exfoliated nanocompound is a complex process in which multiple variables and parameters are involved. The results of the study showed that the feed position of the nanoparticle in the double screw extruder is of vital importance in obtaining an exfoliated film. The maximum temperatures used in the extruder were 170 °C and 130 °C, for polypropylene and polyethylene respectively.     

Dialdehyde cellulose as a niche material for versatile applications: an overview

Cellulose - Dialdehyde cellulose (DAC) has garnered substantial scientific interest, thanks to broad spectrum of possible chemical reactions offered by the aldehyde moieties in its backbone. In the...     

Rheological and anti-microbial study of silica and silver nanoparticles-reinforced k-carrageenan/hydroxyethyl cellulose composites for food packaging applications

Cellulose - Sustainable food packaging films were developed using a combination of k-Carrageenan (k-C), hydroxyl ethyl cellulose (HEC), silicon dioxide (SiO2), and silver (Ag) nanoparticles. The...     

Microwave hydrodiffusion and gravity, a new technique for extraction of essential oils

A new process design and operation for the extraction of essential oils was developed. Microwave hydrodiffusion and gravity (MHG) is a combination of microwaves for hydrodiffusion of essential oils from the inside to the exterior of biological material and earth gravity to collect and separate. MHG is performed at atmospheric pressure without adding any solvent or water. MHG has been compared with a conventional technique, hydrodistillation (HD), for the extraction of essential oil from two aromatic herbs: spearmint (Mentha spicata L.) and pennyroyal (Mentha pulegium L.) belonging to the Labiatae family. The essential oils extracted by MHG for 15 min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained by conventional hydrodistillation for 90 min. MHG also prevents pollution through potential 90% of energy saved which can lead to greenhouse gas emission benefits.     

The effect of chemical composition on microfibrillar cellulose films from wood pulps: water interactions and physical properties for packaging applications

The interactions with water and the physical properties of microfibrillated celluloses (MFCs) and associated films generated from wood pulps of different yields (containing extractives, lignin, and hemicelluloses) have been investigated. MFCs were produced by combining mechanical refining and a high pressure treatment using a homogenizer. The produced MFCs were characterized by morphology analysis, water retention, hard-to-remove water content, and specific surface area. Regardless of chemical composition, processing to convert macrofibrils to microfibrils resulted in a decrease in water adsorption and water vapor transmission rate, both important properties for food packaging applications. After homogenization, MFCs with high lignin content had a higher water vapor transmission rate, even with a higher initial contact angle, hypothesized to be due to large hydrophobic pores in the film. A small amount of paraffin wax, less than 10%, reduced the WVTR to a similar value as low density polyethylene. Hard-to-remove water content correlated with specific surface area up to approximately 50 m²/g, but not with water retention value. The drying rate of the MFCs increased with the specific surface area. Hornified fibers from recycled paper also have the potential to be used as starting materials for MFC production as the physical and optical properties of the films were similar to the films from virgin fibers. In summary, the utilization of lignin containing MFCs resulted in unique properties and should reduce MFC production costs by reducing wood, chemical, and energy requirements.     

Injector-internal thermal desorption from edible oils. Part 2: chromatographic optimization for the analysis of migrants from food packaging material

Injector-internal thermal desorption from edible oil or fat is a convenient sample preparation technique for the analysis of solutes in lipids or extracts from fatty foods. The injector temperature is selected to vaporize the solutes of interest while minimizing evaporation of the bulk material of the oil. This technique has been in routine use for pesticides for some time. Now its potential is explored for migrants from food contact materials, such as packaging, into simulant D (olive oil) or fatty/oily food, which means extending the range of application towards less volatile compounds. The performance for high boiling components was investigated for diisodecyl phthalate (DIDP) and diundecyl phthalate (DUP). Since the injector temperature needs to be as high as 260degreesC, some bulk material of the oil enters the column and must be removed after every analysis. This is achieved by a coated precolumn backflushed towards the end of each analysis. Desorption of the solutes is particularly efficient in the initial phase, when a thin sample film is spread on the liner wall, and is largely determined by the diffusion speed in the oil after the latter has contracted to droplets. An increased carrier gas flow rate during the splitless period supports the transfer into the column. It is concluded that the technique is attractive for migrant analysis, with DUP being at the upper limit of the boiling point.     

Thermal and mechanical characterization of plasticized poly (L-lactide-co-D,L-lactide) films for food packaging

In this work amorphous poly(L-lactide-co-D,L-lactide) (PLLA/PDLLA) was blended with four different commercial adipates to obtain films with enhanced mechanical and thermal properties. Efficiency of plasticizers was evaluated by studying their compatibility with the polymer and their effect on its glass transition temperature. All plasticizers were compatible with the matrix up to a critical composition depending on its molar mass. The addition of plasticizers caused a decrease in elastic modulus and tensile stress, meanwhile elongation at break had a maximum increase for polyadipates with the lower molar mass. Monomeric adipate showed some migration at concentration higher than 10 mass%, while the addition of the higher molar mass plasticizer lead to eventual phase separation. Polyadipates with low molar mass showed a promising behaviour to overcome the brittleness in PLLA/PDLLA films.     

Assessment of specific migration to aqueous simulants of a new active food packaging containing essential oils by means of an automatic multiple dynamic hollow fibre liquid phase microextraction system

The determination of specific migration in the three aqueous food simulants (water, 3% acetic acid and 10% ethanol) from experimental active packaging polypropylene-based films containing natural essential oils as active agents has been carried out for the first time by a two-phase hollow fibre liquid phase microextraction (HFLPME). Due to the high number of variables involved, an experimental design has been applied. High throughput, with six samples running simultaneously in a highly automated system working in dynamic extraction mode, has been achieved. The main analytical characteristics are detection limits as low as 0.01 μg kg⁻¹, linearity higher than 0.99 for almost 5 magnitude orders, average precision below 16% as RSD and concentration factors ranging from 4 to 189. Migration of 43 compounds including terpenes, alkanes, plastic additives and degradation compounds is reported. According to the results obtained and European legislation, the packaging prototypes tested could be safely marketed.     

ZnO/PBAT nanocomposite films: Investigation on the mechanical and biological activity for food packaging

Packaging of foods in high barrier materials is essential to attain food safety. Nanocomposite technology is leading in search of the earlier said kind of packaging materials. The role of zinc oxide (ZnO) loadings on poly(butylene adipate‐co‐terephthalate) (PBAT) structure were investigated, in addition to that packaging properties such as barrier, thermal, and mechanical properties were studied. Antimicrobial films are developed based on PBAT and ZnO nanoparticles. The nanocomposites exhibits a significant increase in the mechanical and thermal stability. The resulting PBAT/ZnO nanofilms show superior antimicrobial activity against Escherichia coli and Staphylococcus aureus. Copyright © 2016 John Wiley & Sons, Ltd.     

Layered double hydroxide films on nanoporous anodic aluminum oxide/aluminum wire: a new fiber for rapid analysis of Origanum vulgare essential oils

Zn/Al layered double hydroxide (LDH) films were fabricated in situ with anodic aluminium oxide aluminium as both the substrate and the sole aluminium source by means of urea hydrolysis. Headspace solid phase microextraction using LDH fibre in combination with capillary GC–MS was utilised as a monitoring technique for the collection and detection of the volatile compounds of Origanum vulgare. Experimental parameters, including the sample weight, microwave power, extraction time and humidity effect, were examined and optimised.     

Monolith as a new sample preparation material: recent devices and applications

Monolith was first used as a material for chromatographic separation two decades ago and solid-phase extraction over 10 years, and since then, separation science has undergone a dramatic change owing to advancements in analytical technology. Recently, monolith has been modified to suit various devices for the extraction and enrichment of analytes in any matrices of environmental, food, and biological analyses. This approach has contributed to miniaturization and automation for sample preparation, and it can reduce the time and cost requirements of sample preparation. Recently, numerous applications have been demonstrated for online and inline preconcentration coupled with monolith, and many kinds of devices have been designed and developed for offline devices. In this review, these applications and devices are listed and discussed in reference to other fields.     

Rhodamine B nanocrystals: elaborations,characterizations and functionalizations for biosensing applications

A biological sensor based on fluorescent organic nanocrystals (NCs) of Rhodamine B grown in sol–gel thin films was developed. The original signalization function is based on fluorescence contrasts of NCs, which exhibit a simple fluorescence signature, good photostability and higher fluorescence intensities compared to dispersed dye molecules. Thanks to a well-controlled dissolution process of the sol–gel surface, accurately followed by atomic force microscopy, the NCs were made emerging just a few nanometers above the silicate thin films to be directly accessible to biological macromolecules. Thus, hairpin-shaped DNA, functionalized by a probe-molecule (DNA probe), has been grafted onto nanocrystal surfaces leading to a fluorescence quenching by Forster resonance energy transfer. After hybridization of these hairpin-shaped DNA probes with their complementary DNA-target, the molecular probes and NCs are pulled apart, stopping thus the quenching. This “turn-on” of nanocrystal fluorescence allows thus a label-free DNA detection. The preparation methodology of the signalization function, its functionalization by hairpin-shaped DNA probes and first DNA-sensor experiments are presented.     

Correlation amongst gas barrier behaviour,temperature and thickness in BOPP films for food packaging usage: A lab-scale testing experience

Permeability of gases in polymers depends strongly upon the polymer structure, the gas type, as well as the conditions of temperature and film thickness. The in-use temperature and thickness of the polymer membrane can play the most important role on preservation and prolongation of food shelf-life. In this work the gas transmission parameters of six Bi-axially Oriented Polypropylene (BOPP) films were investigated as a function of temperature, gas type and thickness. O₂, CO₂, N₂, N₂O, C₂H₄, Air (79%N₂/21%O₂) and Modified Atmosphere (MA) of 79%N₂O/21%O₂ were used as test gas. In order to understand the kinetic of the process, by the activation energy determination, samples were tested at a different temperature, from 10 °C to 40 °C. Gas Transmission Rate (GTR), solubility (S) and diffusion (D) relationship was investigated. The gas/thickness/temperature correlation was reflected in the obtained perm-selectivity ratios and a good linear correlation was found only at 23 °C. Deviations recorded were attributed to temperature fluctuations. Gas transmission process follows the Arrhenius model while the solubility/diffusion process shows consistent deviation, correlated to the temperature and the thickness of the film. By Differential Scanning Calorimetry (DSC) a different crystallinity percentage was recorded, whose influence was evidenced only in the sorption/diffusion processes. The melting temperature remained unchanged. FT-IR Spectroscopy was also carried out to confirm the morphology.     

Processing of wood-based microfibrillated cellulose and nanofibrillated cellulose,and applications relating to papermaking: a review

As an emerging cellulosic nanomaterial, microfibrillated cellulose (MFC) and nanofibrillated cellulose (NFC) have shown enormous potential in the forest products industry. The forest products industry and academia are working together to realise the possibilities of commercializing MFC and NFC. However, there are still needs to improve the processing, characterisation and material properties of nanocellulose in order to realise its full potential. The annual number of research publications and patents on nanocellulose with respect to manufacturing, properties and applications is now up in the thousands, so it is of the utmost importance to review articles that endeavour to research on this explosive topic of cellulose nanomaterials. This review examines the past and current situation of wood-based MFC and NFC in relation to its processing and applications relating to papermaking.     

Metal-organic framework growth at functional interfaces: thin films and composites for diverse applications

Porous metal-organic frameworks (MOFs) are highly ordered crystalline materials prepared by the self-assembly of metal ions with organic linkers to yield low density network structures of diverse topology. MOFs have attracted considerable attention over the last decade due to their facile preparation, tunable pore metrics and the ease of functionalisation of their internal surfaces, such that designer frameworks with exceptional properties for application in gas-storage, separation of small molecules, heterogeneous catalysis and drug delivery are becoming commonplace. For any material to find practical utility however, there is a need for processing and formulation into application-specific configurations. One way to do this is to prepare composite materials where the MOF is supported on a planar substrate or some other shaped body through interaction with functional groups at the support interface. This is a rapidly developing research area, and this review provides an overview of the diverse MOF composite materials prepared up to now, organised by interface type. The importance of the interface is explored within each section and while the overall emphasis is on applications of the composites, coatings and MOF-based devices, the most widely-used and successful synthetic strategies for composite formation are also presented. (183 references).     

Thermal,mechanical and permeation properties of gamma-irradiated multilayer food packaging films containing a buried layer of recycled low-density polyethylene

The effect of gamma radiation (doses 5–60 kGy) on the thermal, mechanical and permeation properties, as well as on IR-spectra of experimental five-layer food packaging films were studied. Films contained a middle buried layer of recycled low-density polyethylene (LDPE) comprising 25–50% by weight of the multilayer structure. Representative films containing 100% virgin LDPE as the buried layer were taken as controls. Results showed that the percentage of recycled LDPE in the multilayer structure did not significantly ($p<0.05$) affect the melting temperature, tensile strength, percent elongation at break, Young's modulus, oxygen, carbon dioxide and water vapour transmission rate values and the IR-spectra of the non-irradiated and irradiated multilayer films. Irradiation (mainly the higher dose of 60 kGy) induced certain small, but statistically significant ($p<0.05$) differences in the mechanical properties of multilayer films (with or without recycled LDPE layer) while no significant differences were observed in the thermal properties and in the gas and water vapour permeability of multilayer films. The above findings are discussed in relation to the good quality of the pre-consumer scrap used in the present study.     

Structural, thermal and optical characterization of a Schiff base as a new organic material for nonlinear optical crystals and films with reversible noncentrosymmetry

Macroscopic single crystals of (E)-5-(diethylamino)-2-((3,5-dinitrophenylimino)methyl)phenol (DNP) were obtained from slow cooling of chloroform or dichlorometane saturated solutions at controlled temperature. X-ray diffraction analysis showed that this compound crystallizes in a noncentrosymmetric space group (P2(1)2(1)2(1)). Thermal analysis was performed and indicated that the crystals are stable until 260 °C. Second-order nonlinear optical properties of DNP were experimentally investigated in solution through EFISH technique and in solid state through the Kurtz-Perry powder technique. Crystals of compound DNP exhibited a second-harmonic signals 39 times larger than of the technologically useful potassium dihydrogenphosphate (KDP) under excitation at infrared wavelengths. In addition, the second-order nonlinear optical properties of DNP were also studied at visible wavelengths through the photorefractive effect and applied to demonstrate dynamic holographic reconstruction.     

Integrating density functional theory and chemical ionization mass spectrometry techniques to assess benzophenone derivatives in food packaging: implications for enhancing food quality and safety

Benzophenone and related derivatives are widely used as photoinitiators for food packaging to cure inks or lacquers with ultraviolet (UV) light on cardboard and paper. However, there are concerns about the potential health risks of their migration into food. Knowing the physical and chemical properties of benzophenone and its derivatives could play a significant role in their quantification and analysis using chemical ionization mass spectrometry (CI-MS) methods. These parameters are evaluated using B3LYP/6-311++** density functional theory (DFT) implemented on Gaussian code. Ion–molecule chemistry through the selection of reagent ions, reaction energetics and kinetics, thermodynamic stability, and reactivity of molecules deemed to foster VOC identification and quantification via CI-MS techniques. The VOCs under study are expected to undergo exothermic reactions from H₃O⁺, NH₄⁺, NO⁺, and O₂⁺ ions, except endothermic proton transfer from NH₄⁺ to 2-hydroxy-4-methoxybenzophenone and 2,3,4-trihydroxy benzophenone. These compounds possess less proton affinities than NH₃ and are least stable in their protonated forms. The DFT computed properties provide the basis for developing reliable and accurate methods to detect and measure the presence of benzophenone and its derivatives in packaging materials and food products.