Analysis of Bioactive Aroma Compounds in Essential Oils from Algerian Plants: Implications for Potential Antioxidant Applications.

In samples of Artemisia campestris (AC), Artemisia herba-alba (AHA) and Salvia jordanii (SJ) essential oils, up to 200 distinct volatile compounds were identified. Using headspace solid-phase microextraction combined with gas chromatography-olfactometry-mass spectrometry (HS-SPME-GC-O-MS), different panelists detected 52 of these compounds. This study offers the most detailed analysis of bioactive compound profiles conducted so far. The most abundant compounds identified were curcumene, making up 12.96% of AC, and camphor, constituting 21.67% of AHA and 19.15% of SJ. The compounds with the highest odor activity value (OAV) were (E,Z)-2,4-nonadienal (geranium, pungent), 3-nonenal (cucumber) and 2-undecenal (sweet) in AC, AHA and SJ, respectively. AHA essential oil showed significant antioxidant activity (IC50 = 41.73 ± 4.14 mg/g) and hydroxyl radical generation (hydroxylation percentage = 29.62 ± 3.14), as assessed by the diphenylpicrylhydrazyl (DPPH) method. In terms of oxygen radical absorbance capacity (ORAC), the strongest antioxidant activity was obtained for SJ essential oil (antioxidant activity of the essential oils, AOX = 337.49 ± 9.87).

Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging.

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0-1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

Evaluation of New Antimicrobial Materials Incorporating Ethyl Lauroyl Arginate or Silver into Different Matrices, and Their Safety in Use as Potential Packaging.

A big challenge for today's industry is antimicrobial preservation and the safety of food. An effective solution to this problem can be a modern invention such as antimicrobial packaging. In the presented research the antimicrobial activity of two new active films incorporating silver, as IONPURE IPL, and ethyl lauroyl arginate (LAE) were evaluated, by employing a low-density polyethylene (LDPE) matrix and a biofilm material, respectively. Additionally, LAE was also incorporated into polystyrene (PS) pads by two different methods: by spraying and by immersion of the PS pads into an aqueous LAE solution. LDPE films containing silver did not show any antimicrobial activity against Escherichia coli and Aspergillus flavus, whereas the biofilm containing LAE reduced the growth of Salmonella enterica but did not inhibit Aspergillus flavus. The active PS pads, both sprayed and immersed in LAE solution, also showed antimicrobial activity, causing a reduction of 99.99% of Pseudomonas putida growth. Thermal treatment at 180 °C for 6 and 15 min did not modify the antimicrobial activity of LAE against Salmonella enterica. Moreover, inductively coupled plasma-mass spectrometry (ICP-MS) analysis was performed to check the migration of silver from developed material intended for food packaging applications into food simulant.

Migration study of organotin compounds from food packaging by surface-enhanced Raman scattering.

The potential of surface-enhanced Raman scattering (SERS) has been investigated for the rapid analysis of two representative organotin compounds (OTCs): dibutyltin maleate (DTM) and tributyltin chloride (TBT), after migration tests from polyvinyl chloride (PVC), as a model food packaging material in aqueous food simulant (acetic acid 3% w/v). OTCs, often used as heat stabilizers additives for PVC, are classified as endocrine disrupting chemicals (EDCs) and their migration potential has to be controlled in compliance with the normative prescriptions for food contact materials. In this study, colloidal silver nanoparticles (AgNPs) were applied as liquid SERS substrate for direct-in-liquid analysis of food simulant after standardized migration tests of PVC samples spiked with OTCs. Promising results were obtained, reaching detection limits below the permitted limits for the considered OTCs (i.e. 0.15 mg/l): DTM and TBT were detected down to 0.01 mg/l and 0.08 mg/l, respectively. Calibration curves were calculated for standard solutions of DTM and TBT in the dynamic range between 0 and 1 mg/l (reduced χ2 = 0.8), and 0.5-5 mg/l (reduced χ2 = 0.2), respectively. Migrated TBT and DTM were detected in the food simulant, specifically identified and quantified by SERS, with a measurement uncertainty around 10% in all cases. In particular, it was found that TBT can migrate in higher amount compared to DTM when the PVC film is in contact with a slightly acidic matrix. These results were further confirmed by inductively coupled plasma-mass spectrometry and UV-Vis spectroscopy. In the present study, direct-in-liquid SERS approach showed to be very promising because it provides a fast response and it allows to overcome most of the common drawbacks of solid SERS substrates due to inhomogeneity problems and low repeatability.

Influence of medicinal and aromatic plants into risk assessment of a new bioactive packaging based on polylactic acid (PLA).

A new biodegradable antioxidant active packaging for food applications based on antioxidants from medicinal and aromatic plants incorporated into a polylactic acid matrix was designed and developed. Melt blending processing technique was applied to prepare polylactic acid films loaded by sage and lemon balm leaves. Antioxidant properties of developed active films were investigated using the following methods: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl and a home-made generator of hydroxyl radicals. In addition, reducing power and total phenolic content of polylactic acid films were checked. The results of antioxidant capacity showed that percentage of hydroxylation for active film with lemon balm and sage was 55.5% ±â€¯0.1% and 67.4% ±â€¯0.3%, respectively. The reducing power of active films increased 8 times in comparison to the blank samples. Moreover, extensive investigation of influence of sage and lemon balm leaves on material safety and type of migrants was performed using migration assays. The composition of both non-volatile and volatile compounds of different active packaging films was compared with neat polylactic acid film. Three different food simulants such as 95% (v/v) ethanol, 10% (v/v) ethanol and 3% (w/v) acetic acid were checked. It was shown that the addition of sage and lemon balm leaves into a polylactic acid structure decreased the migration of both linear and cyclic polylactic acid oligomers, currently not legislated by European Union. Besides, total absence or decrease of migration of volatile compounds were observed when using the active films. Both thermal and mechanical properties of films were also evaluated.

Raman spectroscopy, electronic microscopy and SPME-GC-MS to elucidate the mode of action of a new antimicrobial food packaging material.

One critical challenge when developing a new antimicrobial packaging material is to demonstrate the mode of action of the antimicrobials incorporated into the packaging. For this task, several analytical techniques as well as microbiology are required. In this work, the antimicrobial properties of benzyl isothiocyanate, allyl isothiocyanate and essential oils of cinnamon and oregano against several moulds and bacteria have been evaluated. Benzyl isothiocyanate showed the highest antimicrobial activity and it was selected for developing the new active packaging material. Scanning electron microscopy and Raman spectroscopy were successfully used to demonstrate the mode of action of benzyl isothiocyanate on Escherichia coli. Bacteria exhibited external modifications such as oval shape and the presence of septum surface, but they did not show any disruption or membrane damage. To provide data on the in vitro action of benzyl isothiocyanate and the presence of inhibition halos, the transfer mechanism to the cells was assessed using solid-phase microextraction-gas chromatography-mass spectrometry. Based on the transfer system, action mechanism and its stronger antimicrobial activity, benzyl isothiocyanate was incorporated to two kinds of antimicrobial labels. The labels were stable and active for 140 days against two mould producers of ochratoxin A; Penicillium verrucosum is more sensitive than Aspergillus ochraceus. Details about the analytical techniques and the results obtained are shown and discussed. Graphical Abstract Antimicrobial evaluation of pure compounds, incorporation in the packaging and study for mode of action on S. coli by Raman, SEM and SPME-GC-MS.

Influence of oxygen and long term storage on the profile of volatile compounds released from polymeric multilayer food contact materials sterilized by gamma irradiation.

The profile of volatile compounds released from 13 different multilayer polymeric materials for food use, before and after their exposure to gamma radiation, has been assessed by solid-phase microextraction-gas chromatography-mass spectrometry. Thermosealed bags of different materials were filled with either air or nitrogen to evaluate the oxygen influence. One-third of the samples were analyzed without irradiation, whereas the rest were irradiated at 15 and 25 kGy. Half of the samples were processed just after preparation and the other half was stored for 8 months at room temperature prior to analysis. Very significant differences between unirradiated and irradiated bags were found. About 60-80 compounds were released and identified per sample. A huge peak of 1,3-ditertbutylbenzene was present in most of the irradiated samples. An outstanding reproducibility in all the variables evaluated (chromatograms, oxygen percentage, volume of bags) was noticed. Independently of filling gas, the results of unirradiated materials were almost identical. In contrast, the chromatographic profile and the odor of irradiated bags filled with nitrogen were completely different to those filled with air. Principal component analysis was performed and 86.9% of the accumulated variance was explained with the first two components. The migration of compounds from irradiated materials to the vapor phase was much lower than the limits established in the Commission Regulation (EU) No 10/2011.

Analytical procedure for the determination of Ethyl Lauroyl Arginate (LAE) to assess the kinetics and specific migration from a new antimicrobial active food packaging.

Ethyl Lauroyl Arginate (LAE) is a cationic tensoactive compound, soluble in water, with a wide activity spectrum against moulds and bacteria. LAE has been incorporated as antimicrobial agent into packaging materials for food contact and these materials require to comply with the specific migration criteria. In this paper, one analytical procedure has been developed and optimized for the analysis of LAE in food simulants after the migrations tests. It consists of the formation of an ionic pair between LAE and the inorganic complex Co(SCN)(4)(2-) in aqueous solution, followed by a liquid-liquid extraction in a suitable organic solvent and further UV-Vis absorbance measurement. In order to evaluate possible interferences, the ionic pair has been also analyzed by high performance liquid chromatography with UV-Vis detection. Both procedures provided similar analytical characteristics, with linear ranges from 1.10 to 25.00 mg kg(-1), linearity higher than 0.9886, limits of detection and quantification of 0.33 and 1.10 mg kg(-1), respectively, accuracy better than 1% as relative error and precision better than 3.6% expressed as RSD. Optimization of analytical techniques, thermal and chemical stability of LAE, as well as migration kinetics of LAE from experimental active packaging are reported and discussed.

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 microg 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.

Determination of the antioxidant capacity of active food packagings by in situ gas-phase hydroxyl radical generation and high-performance liquid chromatography-fluorescence detection.

An experimental laboratory-made assembly to determine for the first time the antioxidant capacity with respect to hydroxyl (OH*) radicals of several new active packagings directly in the materials has been developed. Gas-phase OH* radicals are generated by UV-light irradiation of an aqueous H(2)O(2) aerosol. After on-line reaction with up to eight parallel test samples, remaining OH* is quantitatively trapped by a salicylic acid solution, and antioxidant capacity is indirectly assessed by HPLC-fluorescence determination of the high sensitive 2,5-dihydroxybenzoic acid formed. Several natural essential oils as well as active plastic films including in their formulation such oils have been subjected to oxidation. Polymers containing clove and oregano were the most efficient ones (up to 7.2 and 4.7 times, respectively, more antioxidant than blanks), whereas rosemary, citronella and propolis showed average efficiency. On the other hand, active materials containing ferulic acid, quercetin, catechin and thymol, as well as commercial active bags with ethylene-absorption properties, showed limited or none antioxidant protection. Experimental results and full details about experimental assembly are given.

Development of an automatic multiple dynamic hollow fibre liquid-phase microextraction procedure for specific migration analysis of new active food packagings containing essential oils.

A two-phase based hollow fibre liquid-phase microextraction (HFLPME) with a high automatization degree and able to process up to six samples simultaneously by means of a multiple channel syringe pump has been successfully developed. The experimental set-up allows to carry out dynamic extractions with a considerable reduction of sample handling. The system has been applied for the first time to the determination in aqueous food simulant of migrants from prototypes of active packagings to assess their safety before marketing, showing detection limits in the ng g(-1) range, relative standard deviations below 13% and concentration factors ranging from 83 to 338.

Stabilization of beef meat by a new active packaging containing natural antioxidants.

A new antioxidant active packaging material for food has been designed and developed, consisting of a polypropylene film in which some natural antioxidants have been immobilized. The antioxidant properties of the new material have been tested by using both pure myoglobin and fresh beef steaks. Two different cell configurations (glass vial and Petri dish) and four different myoglobin concentrations-according to the common content of this compound in fresh meat and meat derivatives (1080, 1995, 3332, and 4414 microg g(-1), respectively)-have been evaluated in oxidation studies. Furthermore, three different concentrations of natural antioxidants in the film (designated as PR1, PR2, and PR3) were evaluated. Once myoglobin samples and the active films were introduced in the cell, they were exposed to cool white fluorescent light to accelerate oxidation for a period of time ranging from 5 to 30 days. Remaining myoglobin concentration was measured by molecular absorption UV-vis spectrophotometry at 409 nm. Organoleptic properties and color, texture, and physical characteristics of fresh meat packaged with the new active film have also been measured to evaluate the shelf life of the packaged meat. Results showed that, compared to normal polypropylene, the active film containing natural antioxidants efficiently enhanced the stability of both myoglobin and fresh meat against oxidation processes, thus being a promising way to extend the shelf life of fresh meat.

Migration studies to assess the safety in use of a new antioxidant active packaging.

Both specific and overall migration tests have been applied to new experimental food packaging-active plastic films with antioxidant properties, including in its composition a natural rosemary extract. Determination of volatile and semivolatile compounds migrating from plastic to the four established simulants showed that both specific and overall migration was very low. The results obtained gave values 20 times lower than the established limits in the worst case. So, from the point of view of health risk, the new active packaging can be considered as safe. Analytical procedure used provided the necessary information about the migration behavior, with good analytical characteristics and detection limits in the sub mug kg(-1) range. Besides, no significant difference was found between laboratory and factory-made samples, which is an important issue for industrial production, the next step in the development of the new antioxidant active film.

Subcritical water and dynamic sonication-assisted solvent extraction of fluorescent whitening agents and azo dyes in paper samples.

Two low-volume solvent continuous extraction methods are applied to the extraction of paper matrices. In the methods reported here, a complex mixture of fluorescent whitening agents (FWAs) and azo dyes (AZOs) used in paper materials intended to come into contact with foodstuffs was extracted by using subcritical water extraction (SWE) and dynamic sonication-assisted solvent extraction (DSASE). Rationale for the work is based upon migration concerns of these groups of analytes from the packaging to the packaged items, thus compromising their subjective and/or objective quality. In SWE, sample was extracted in 21 min with 0.5 mL of water, whereas the DSASE method required 11 min and used 7 mL of water. DSASE was further developed by incorporating an organic modifier in order to change water polarity, thus improving extraction of moderately polar analytes. This way, modified-DSASE used a total organic volume of 0.9 mL which represents a reduction of 200 times in organic solvent consumption (200 mL versus approximately 1.0 mL) and 11 times in extraction time (2h versus 11 min) compared to the existing methods. SWE was able to extract only 9 out of 12 test analytes with average recoveries between 10 and 25% whereas modified-DSASE succeed in extracting all the target analytes with an average recovery of 89%. Complete discussion and explanation concerning these differences are provided in the text.

Determination of potential migrants in polycarbonate containers used for microwave ovens by high-performance liquid chromatography with ultraviolet and fluorescence detection.

The determination of several compounds present in a commercial polycarbonate container intended to be used in microwave ovens which could be considered as potential migrants has been carried out by reversed-phase high-performance liquid chromatography (HPLC) with both ultraviolet (UV) and fluorescence detectors. Total dissolution with dichloromethane and polymer reprecipitation with methanol have been used to evaluate 100% potential migration as the worst case. The extract consisted of a complex mixture containing monomers, oligomers, UV stabilizers, antioxidants, degradation products, and other additives. Phenol, Bisphenol A, 2,4-di-tert-butylphenol, Cyasorb UV5411, bis(2-ethylhexylphthalate), Irganox 1076, and Irgafos 168 were identified by both retention times and fluorescence-to-UV ratios. Additional confirmation was achieved by HPLC with diode array detection and gas chromatography-mass spectrometry. Recovery percentages were in the range of 73.8-94.4%, the lowest one being for the antioxidant Irgafos 168 due to its transformation into the phosphate form and 2,4-di-tert-butylphenol. The concentrations of the studied analytes present in the polycarbonate container ranged between 0.9 and 240 microg.g(-)(1). The total dissolution conditions that may affect the final concentration of analytes, mainly Bisphenol A, are discussed.