Search

Almost all processed food comes packaged in either plastic, glass, metal, or paper and paperboard materials, and many packaging materials are disposed of after a single use (linear economy). Based on the concept of a circular economy, the recycling of food packaging materials has become one of the main targets for industries and regulators around the world. However, recycling presents particular challenges, mainly related to the recycled material composition, which determines its reusability, application, functionality, and chemical safety. In this latter matter, it has been demonstrated that the use of recycled food packaging materials increases the number and possible sources of substances that could be present in the packaging material, which is of concern as substances that can migrate into food and cause health hazards upon consumption. This review compiles information regarding substances detected in non-permanent food packaging materials, focusing mainly on plastics, paper, and paperboards. The compilation of literature studies (110 research articles) on the presence of intentionally added substances (IAS) and non-intentionally added substances (NIAS) in food packaging materials, their migration, toxicity, and dietary exposure has been summarized, evaluated, and discussed. In addition, current sustainable food packaging trends have been mentioned. Finally, approaches to reduce the presence, migration, and potential exposure to substances that have migrated from packaging materials into food have been reviewed.

A simple and rapid electrochemical method was established to quantify the total polyphenol (TP) content and assess their antioxidant activity (AA) in roots of three Echinacea purpurea (E. purpurea) species using square wave voltammetry (SWV). Individual polyphenol components were identified, and then quantified by ultra-high performance liquid chromatography coupled with mass spectrometery (UPLC-MS). Two major polyphenols, chicoric (ChA) and caftaric (CFT) acids, were identified by mass spectroscopy in the extract of E. purpurea samples. The Accuracy of the proposed SWV electrochemical method for TP content and AA analysis was validated by the highly sensitive UPLC-MS technique and standard ABTS method, respectively. A high correlation was noticed between the results, indicating the high sensitivity and reliability of the proposed SWV method for polyphenols analysis and AA evaluation in natural herbal samples.

Morphologically well-defined rods of approximately 1 cm in length are effectively and economically obtained by mixing ortho-phenylenediamine (30 mmol L−1) with ammonium persulfate (12.5 mmol L−1) in an acidic solution (0.37 mol L−1 HCl) at room temperature with and without the presence of 50 mmol L−1 aniline. These self-assembled, morphologically uniform products can be potentially scaled up and used as morphological templates to fabricate well-defined structures of other materials such as conducting polymers. The products were characterized using Raman, UV-visible, high-resolution NMR (1H and 13C) and mass spectroscopies, X-ray diffraction, scanning electron microscopy and elemental analysis. Apart from certain differences in visual appearance and in X-ray diffractograms, other analytical data suggest that there are no structural changes upon addition of aniline into the reaction mixture. NMR and mass spectra imply that all syntheses carried out either with or without aniline result in a mixture of two products, attributed to 2,3-phenazinediamine and 3-aminophenazin-2-ol. A formation mechanism based on hydrogen bonding and π–π stacking has been proposed. © 2015 Society of Chemical Industry

Sauvignon blanc wines often have complex aromatic profiles with flavours ranging from herbaceous to tropical. The formation of volatiles during fermentation is critical for the aromatic bouquet of a wine. Oxygen and sulfur dioxide additions to the must can influence the formation of these compounds. However, the effect of different, controlled oxygen and sulfur dioxide additions to Sauvignon blanc must and the changes it induces in the corresponding wines has not been investigated in detail. The present study evaluated how controlled oxygen and sulfur dioxide additions to Sauvignon blanc must affects the levels of volatile and non-volatile compounds, including the methoxypyrazines, volatile thiols, esters, alcohols, fatty acids, monoterpenes, glutathione and phenolics. It was evident that the presence of sulfur dioxide resulted in wines with higher concentrations of certain compounds. Copyright © 2013 John Wiley & Sons, Ltd.

Composite hollow microspheres consisting of polyaniline (PANI) and indomethacin (IND) are prepared through a self-assembly process in a mixed methanol/water solutions. Different volume fractions of methanol to water and different aniline concentrations are investigated to obtain the optimal conditions for the formation of PANI/IND composite hollow microspheres. The morphologies of the PANI/IND composites are characterized, showing the inner hollow center of the microspheres. Spectroscopic characterizations reveal that the synthesized materials have many typical features of chemically synthesized PANI and confirm the presence of IND in the composites. A controlled release of IND is achieved by adjusting the pH value of the buffer solution.

Although many methods are available for the evaluation of the antioxidant capacity of samples presented in the liquid state, typically food and beverages, to date only the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) assay has been applied to the measurement of the antioxidant capacity of solid samples such as active packaging materials. A modified 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assay has been successfully developed for the measurement of the antioxidant capacity of conducting polymer powders. The ABTS•+ radical scavenging activity of polypyrrole (PPy), polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT) powders was compared. The ranking order for greatest antioxidant capacity among the conducing polymer powders was PANI > PPy > PEDOT. The reduced forms of all the three conducting polymer samples were found to show greater radical scavenging activity than their as-prepared partially oxidized forms. The modified ABTS assay is a simple, rapid and sensitive method for evaluating the antioxidant capacity of conducting polymer powders. The method is also suitable for composite antioxidant materials comprising a conducting polymer and a conventional packaging polymer. Copyright © 2010 Society of Chemical Industry

Summary: Hollow microspheres of PEDOT (poly(3,4-ethylenedioxythiophene) ranging from 0.5 to 10 µm have been synthesized by chemically oxidative polymerization of EDOT(3,4-ethylenedioxythiophene) using ammonium persulfate in a catanionic surfactant solution obtained by mixing cetyltrimethylammonium bromide (CTAB) and sodium dodecylbenzenesulfonate (SDBS). The effect of the molar ratio of CTAB to SDBS on the morphology of the PEDOT oxidation products has been investigated using SEM and TEM and by an analysis of the structural properties using UV-visible, FTIR and Raman spectroscopies, elemental analysis and conductivity measurements. The electro-catalytic activity of PEDOT hollow microspheres for the oxidation of ascorbic acid was investigated by cyclic voltammetry in a pH 6 citrate/phosphate buffer solution and compared to the activity of granular PEDOT particles formed in the absence of the catanionic surfactant.

Self-assembled hollow nanosphere composites of polyaniline and Au nanoparticles (PANI-p-TSA/Au) were chemically synthesized from solutions containing p-toluenesulfonic acid (p-TSA) with the addition of gold chloride trihydrate as the oxidant. The composite materials were characterized by SEM, TEM, and a range of spectroscopic methods. Spectroscopic characterizations confirmed that the polymeric product is a form of doped PANI, while electron diffraction and X-ray diffraction showed that elemental Au was present in the PANI-p-TSA/Au nanocomposites. The room temperature electrical conductivity of the PANI-p-TSA/Au nanocomposites was two orders of magnitude greater than a PANI-p-TSA obtained in the presence of ammonium persulfate as the oxidant under the same conditions.

Self-assembled nanotubular structures of polyaniline were chemically synthesized from solutions containing different amino acids with the addition of ammonium persulfate as the oxidant. The materials were characterized by SEM and a range of spectroscopic methods. Spectroscopic characterizations revealed that the synthesized materials had many features typical of chemically synthesized PANI. Some additional features were also found and have been ascribed to non-conducting material formed in the initial stages of the reaction at a higher solution pH. However, UV-vis and 13 C NMR spectra point toward a conductive material as the final product of the reaction. Cyclic voltammetry results also indicate an electroactive final product that closely resembles regular PANI in its electrochemical characteristics.

Template-free, self-assembled polyaniline (PANI) nanotubes were prepared in a solution of poly(methyl vinyl ether-alt-maleic acid) (PMVEA) by oxidative polymerization using ammonium persulfate as the oxidant. The weight ratio of the polymeric acid to aniline in the solution had a significant effect on the size of the polyaniline nanotubes as determined by SEM. The outer diameter of the nanotubes increased from 65 nm to 160 nm with increased levels of PMVEA in the reaction solution from 1 to 4 wt/v%. The PANI/PMVEA nanotubes were characterized by FTIR and cyclic voltammetry. The nanotubes were used to construct a simple electrochemical oligonucleotide (ODN) sensor where ODN probes were covalently grafted onto the residual carboxylic acid functionalities on the nanotubes. The potential pulse amperometry technique was used to obtain a direct and fast electrochemical readout.

A range of physico-chemical properties of 21 Californian red wines from 1 to 28 years old were correlated with wine age. The level of monomeric phenolics and low molecular-weight phenolic oligomers decreased with age, while the level of high molecular-weight phenolics increased. On the other hand, total phenols given by the Folin–Ciocalteau method, antioxidant capacity determined using a controlled chain reaction of methyl linoleate and the intensity of the anodic peak determined by cyclic voltammetry (CV) did not show any significant correlation with wine age. Total phenols and the shapes of CV traces were more dependent on the grape variety and the particular viticultural and wine-making practices rather than on wine age. At the same time, young and aged wines showed a pronounced difference in the shape of [O2] traces recorded during the oxidation of methyl linoleate in a micellar solution inhibited by wine addition. Possible reasons why the antioxidant activity of red wines does not correlate with wine age are discussed. Copyright © 2006 Society of Chemical Industry

The change in the dielectric properties of frozen 200 g kg−1 maltodextrin solutions upon warming has been recorded using a capacitance meter and a dielectric thermal analysis instrument. The capacitance and permittivity increased by several orders of magnitude after melting, and higher values were obtained at a higher measurement frequency or with added NaCl, while a marked increase (labelled Trise) was seen close to the glass transition temperatures measured by differential scanning calorimetry. The transition temperatures shifted to more negative values by 4–6 °C upon the addition of 0.1 mol kg−1 NaCl, consistent with the freezing point depression of the freeze-concentrated solutions. Copyright © 2004 Society of Chemical Industry

Shelf-life estimation for frozen foods can be a long process because of the long duration of shelf-life at the lower temperatures of storage. A variety of rapid procedures have been proposed to suggest whether products will have acceptable shelf-lives at low storage temperatures. These all have limitations. In this paper a new procedure is proposed which involves direct determination of shelf-lives at the more elevated frozen storage temperatures, where change is more rapid. This is coupled with utilisation of information on the mobility temperature to establish a low-temperature storage datum. A plot of expected shelf-life as a function of temperature is produced using these two data sources. The effectiveness of the procedure is validated using existing literature data and newly generated data. The procedure allows for the effective estimation of the low-temperature storage life of a product utilising data collected on the product in question. It requires around 60 days, while effectively estimating the storage temperatures required to achieve target shelf-lives of 1 year, 18 months, 2 years or even longer.

Anthocyanin biosynthesis in leaves increases under stresses which also generate reactive oxygen species (ROS). In the present study the hypothesis that red leaves are better equipped to scavenge ROS than green leaves was tested. Antioxidants in leaf extracts from red and green morphs of Elatostema rugosum were identified, and activities quantified using enzymatic and α,α-diphenyl-β-picrylhydrazyl (DPPH) assays and cyclic voltammetry. Red leaves from E. rugosum held greater amounts of superoxide dismutase, catalase, anthocyanins, and hydroxycinnamic acids, were significantly more effective at scavenging DPPH radicals, and produced higher voltammetric currents than green leaves. Anthocyanins contributed to the antioxidant pool more than all other constituent phenolics. Anthocyanin concentrations, and antioxidant activities declined with leaf age. Purified anthocyanin fractions displayed oxidative activities at both pH 7·0 and pH 5·5. Implications of the antioxidant potential of anthocyanin in its cytoplasmic and vacuolar locations are discussed.

Reverse phase HPLC has been applied to quantify levels of polymethoxylated flavones and carotenoids in orange and tangelo juices. Lower levels of sinensetin and tetramethyl-o-scutellarein and higher levels of heptamethoxyflavone and tangeretin relative to nobiletin indicated the addition of tangelo to orange juice. β-Cryptoxanthin and its esters, identified by positive ion electrospray mass spectrometry, were present in larger amounts relative to β-carotene in tangelo than in orange juice. Using canonical discriminant analysis, the addition of 100 g kg -1 tangelo to orange juice can be detected. Le jus du tangelo, un fruit hybride de la mandarine et du pomelo, ressemble au jus d'orange douce dans sa couleur et sa flaveur. Dans cette etude, la chromatographie HPLC en phase inverse est appliquee pour quantifier les flavones et les carotenoides polymethoxyles dans les jus d'orange et de tangelo. Le jus de tangelo differe du jus d'orange par des teneurs plus elevees en heptamethoxyflavone, en tangeretine et en β-cryptoxanthines.

Redox potentials in wine were observed to be lower at platinum than at gold electrodes, while higher values were seen at glassy carbon. These differences are explained in terms of mixed potentials involving principally ethanol oxidation coupled to H+ and O2 reduction, while other electroactive species are also expected to contribute. The redox potentials of a range of red and white wines were similar, suggesting that phenolic antioxidants are not sufficiently electroactive to markedly affect the measured potential. The redox potential still provides a useful measure for characterizing conditions under which phenolic antioxidants are stable against oxidative degradation.

The reduction of CO2 has been examined at gold and platinum microelectrodes in solutions of 0.1 M tetraethylammonium perchlorate (TEAP) in dimethyl sulfoxide (DMSO), acetonitrile (MeCN) and mixed solvent systems. The gold microelectrode in 90 % MeCN/10 % DMSO produced currents 4 times larger than in pure DMSO while still showing a large potential window over which reduction currents can be measured. Films of polyaniline were insoluble in MeCN and acted as a diffusional barrier for CO2 reduction. Polyaniline was soluble in DMSO solutions, but the adsorbates which remained following polyaniline dissolution helped to lower the CO2 reduction overpotential, producing a broad current plateau of 500 mV for the measurement of CO2 concentrations.

The formation of CuSeCN on a copper anode was studied in 0·1 and 0·5 mol dm-3 KSeCN solutions. A thin film of polycrystalline CuSeCN was produced with a midpoint potential between the anodic and cathodic peaks for 0·1 mol dm-3 KSeCN at - 0·253 V, close to the open-circuit potential of - 0·249 V. A precursory anodic peak or shoulder was seen at about - 0·210 V, and was ascribed to the formation of a primary (barrier) film. The anodic peak currents for the primary film were linearly dependent upon the sweep rate. Potential steps into the primary film region produced current transients, with the current decaying in proportion to the reciprocal of time. The anodic peak current and potential for the secondary polycrystalline film were proportional to the square root of the sweep rate, an effect which is consistent with a model for porous film growth controlled by the resistance across the underlying barrier film. A weak Raman band due to Se-bonded CuSeCN at 2164 cm-1 was also observed in situ.

Free-standing films of polypyrrole doped with p-toluene sulfonate (PPy/pTS) were electropolymerized galvanostatically at different deposition current densities and their electrochemomechanical deformation (ECMD) properties were measured in situ during cyclic voltammetry experiments. It was found that films exhibiting a higher cation-driven actuation strain were generated when a lower current density was used in electropolymerization, which also led to an increase in PPy conductivity and doping level. A decrease in cation-driven strain with time was observed in all cases due to a loss of pTS anions from the films. Raman, FTIR, and elemental analyses were used to characterize the films grown at different deposition current densities and no sign of excessive overoxidation was found. SEM images revealed that the morphology of the films was affected by the current density during electropolymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Objective: To determine whether serum antioxidant capacity measured by the electrochemical technique of cyclic voltammetry (CV) could resolve differences in severity of the inflammatory disease acute pancreatitis. Methods: Experimental animal study using male Wistar rats. Group 1 (baseline), immediate euthanasia with no surgical interventions; Group 2 (sham), identical surgical procedures to the pancreatitis groups but no intraductal infusion; Groups 3–5, acute pancreatitis induced by intraductal infusion of 3%, 4% or 5% sodium taurocholate respectively. Terminal blood and pancreatic tissue samples for CV, biochemistry and histology were collected at 12 h (Groups 2–5). Results: There was a significant positive correlation of the first serum cyclic voltametric peak current maxima (CVi1) with pancreatic histological severity (Spearman r = 0.51, p = 0.007) as well as with a number of other markers of systemic disease severity, notably bicarbonate (r =−0.57, p = 0.002), base excess (r =−0.65, p < 0.001) urea (r =−0.68, p < 0.001) and calcium (r =−0.60, p = 0.008). CVi1 was superior at indicating the severity of the disease state compared to a standard method of total antioxidant capacity measurement. Conclusions: CV was found to be a simple, technique that could differentiate between the physiological and histological severities of acute pancreatitis. Further clinical studies are now justified to determine if point-of-care CV offers prognostic and treatment-monitoring advantages for severe acute inflammatory illnesses within the critical care setting.