1,721,006 research outputs found
Application of LC with Evaporative Light Scattering detector for biogenic amines determination in fair tradee cocoa-based products
No full textIn this study, the separation of eight biogenic
amines (cadaverine, serotonin, histamine, spermidine,
spermine, tyramine, putrescine and β-phenylethylamine) by
a liquid chromatography (LC) method with evaporative light
scattering detection (ELSD) was performed. The LC–ELSD
method was validated by comparison of the results with those
obtained through LC–ultraviolet (UV) determination, based
on a pre-column dansyl chloride derivatisation step, and the
recorded data showed as both analytical methods can be interchangeably
used for biogenic amines determination. LC–
ELSD methodology showed good precision and permitted to
achieve, for standard solutions, limits of detection (LOD)
ranging from 0.01 to 0.02 μg ml−1 and limits of quantitation
(LOQ) ranging from 0.03 to 0.05 μg ml−1. The whole methodology,
comprehensive of the homogenization–extraction
process and LC–ELSD analysis, has been applied in the analysis
of several samples of fair trade cocoa derivatives. The
most abundant amine found was histamine for a total amount
of biogenic amines in the range 5.81–38.82 μg g−1. The
highest amounts of biogenic amines (BAs) were found in the
most processed products but never representing a possible risk
for consumer health, according to the toxicity levels reported
in literature and regarded as acceptable
Cambiamenti nel profilo di ammine biogene durante il periodo di conservazione di campioni di bottarga
No full textCambiamenti nel profilo di ammine biogene durante il periodo di conservazione di campioni di bottarg
Biogenic amines as quality marker in organic and fair-trade cocoa-based products
No full textIn this study the separation of eight biogenic amines (cadaverine, serotonin, histamine, spermidine,
spermine, tyramine, putrescine and -phenylethylamine) by an LC method with evaporative light
scattering detection (ELSD) was performed. The LC–ELSD method was validated by comparison
of the results with those obtained through LC–UV determination, based on a pre-column dansyl
chloride derivatisation step and the recorded data showed as both analytical methods can be
interchangeably used for biogenic amines determination. The analysis of several samples of fair
trade cocoa-derivatives, coupled with results on organic cocoa-based products previously obtained,
showed that both classes of samples always contain less amines concentrations in comparison with
their conventional counterparts, supporting the idea that BAs can be regarded as cocoa quality
markers
Synthesis of protein-based hydrogel for pharmaceutical and biomedical applications
No full textNatural polymers, such as proteins, are materials extensively investigated due to their biocompatibility, biodegradability and non-toxic and non-immunogenic characteristics. Enclosing these biomacromolecules in a complex structure, these features can be transferred to a biomaterial in order to extend the performance of the device. Thus, the covalent conjugation of a biodegradable macromolecule, as a protein, represents a versatile strategy to produce intelligent biodegradable hydrogels, suitable for pharmaceutical and biomedical applications. The cross-linking of biomacromolecules is somewhat important in these fields because it increase the mechanical properties of the hydrogels without to affect, in severe degree, the biodegradability. Basically, albumin and gelatin represents the protein mainly used in the biomedical field and their insertion in a polymeric network was performed employing different synthetic strategy involving the functional groups in the side chain of the polypeptides. Hydrogel containing proteic moieties in the polymeric network can be achieved by thermal denaturation of the protein either by direct reaction between functional groups (usually carboxyl and amino goups) in the polypeptide side chains and also by use chemical cross-linking agents as bifunctional carbonyl reagents. Finally, involving the protein in a radical process innovative synthetic procedures were proposed in order to modify polymeric network composition and to design hydrogels with appropriate and mouldable physicochemical properties
Food Applications of Active and Intelligent Packaging: Legal Issues and Safety Concerns
No full textUnlike traditional packaging, which must be totally inert, active packaging is designed to interact with the contents and/or the surrounding environment. Active packaging systems are successfully used to increase the shelf life of processed foods and can be categorized into adsorbing and releasing systems. Intelligent packaging is characterized by its ability to monitor the condition of packaged food or the environment by providing information about different factors during transportation and storage including time-temperature indicators, gas detectors, and freshness and/or ripening indicators. At the same time, advances in nanotechnology and the improvement of nanomaterials will enable the development of better and new active and intelligent packaging. Until 2004 in Europe there was a legislative lack for these kinds of packaging decreasing their penetration in the EU market. To face the problem Regulation 1935/2004/EC and more specifically Regulation 450/2009/EC set new legal basis for their correct use, safety and marketing
Imprinted hydrophilicnanospheres as drug delivery systems for 5-fluorouracil sustained release
No full textMolecularly imprinted hydrogel nanospheres as devices for the controlled/sustained release of 5-fluororacil in biological fluidswere synthesized employing one-pot precipitation technique as the polymerization method. Methacrylic acid as a functionalmonomer and ethylene glycole dimethacrylate as a cross-linker were used in polymeric feed. Morphological and hydrophilicproperties were determined by scanning electron microscopy and water content measurement, and recognition and selectivityproperties of spherical molecularly imprinted polymers were compared with the spherical non-imprinted polymers, both inorganic (acetonitrile) and water media. Finally, in vitro release studies were performed in plasma simulating fluids
Flavonoids preservation and release by methacrylic acid-grafted (N-vinyl-pyrrolidone)
No full textContext: Flavonoids preservation and release. Objective: Synthesis of a polymeric material able to prevent thermal and photo degradation of a flavonoid model compound, such as (+)-catechin, and suitable for a controlled/sustained delivery of this molecule in gastro-intestinal simulating fluids. Materials and methods: Methacrylic acid (MAA) was grafted onto poly(N-vinyl-pyrrolidone) (PVP) by a free radical grafting procedure involving a single-step reaction at room temperature. For this purpose, hydrogen peroxide/ascorbic acid redox pair was employed as water-soluble and biocompatible initiator system. Results and discussion: FT-IR spectra confirmed the insertion of MAA onto the polymeric chain. Stability studies, performed under various conditions, such as freeze-thaw cycles, exposure to strong light, thermal stability studies under constant humidity and with light protection at different temperatures, showed the preservative properties of the polymeric material towards flavonoids. Furthermore, the biocompatibility was highlighted by Hen's Egg Test-Chorioallantoic Membrane assay and in vitro release studies demonstrated the possibility to employ PVP-MAA copolymer as a device for gastro-intestinal release of flavonoids. Conclusion: The coupling of good preservative properties together with biocompatibility and the usefulness as carrier in controlled release make this kind of material very interesting from an industrial point of view for different applications in food, pharmaceutical, and cosmetic fields
Ferulic acid as a comonomer in the synthesis of a novel polymeric chain with biological properties
No full textIn this study, ferulic acid was copolymerized with methacrylic acid to obtain a useful material with both antioxidant and antifungal properties. An ascorbic acid/hydrogen peroxide redox pair was used as a water-soluble and biocompatible initiator system to prime the one-pot polymerization reaction. The obtained material was characterized with gel permeation chromatography, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and fluorescence analyses, and the disposable phenolic group content was determined to verify the insertion of ferulic acid into the polymeric backbone. Finally, the antioxidant and antifungal activities were demonstrated toward the hydroxyl radical and Aspergilliis niger, respectively
Negative thermo-responsive microspheres based on hydrolyzed gelatin as drug delivery device
No full textNovel stimuli-responsive hydrophilic microspheres were prepared by free radical polymerization of hydroxyethyl methacrylate (HEMA) and methacrylic acid (MA), as hydrophilic monomers, and N-isopropylacrylamide (NIPAAm) and N,N′-ethylenebisacrylamide (EBA), as thermo-sensitive monomer and crosslinker, respectively. Hydrophilic comonomers were introduced in the macromolecular network to synthesize materials with tunable thermal behavior. In addition, by introducing in the polymerization feed both a hydrophilic and a pH-sensitive monomer, such as MA, dual stimuli-responsive (pH and temperature) hydrogels were synthesized. The incorporation of monomers in the network was confirmed by infrared spectroscopy, while the network density and the shape of hydrogels was found to strictly depend on the concentration of monomers in the polymerization feed. Thermal analyses showed negative thermo-responsive behavior with pronounced water affinity of microspheres at a temperature lower than lower critical solution temperature (LCST). In our experiment, the LCST values of the hydrogels were in the range 34.6–37.5°C, close to the body temperature, and the amount of hydrophilic moieties in the polymeric network allows to collect shrinking/swelling transition temperatures higher than the LCST of NIPAAm homopolymers. In order to test the preformed materials as drug carriers, diclofenac diethylammonium salt (DDA) was chosen and drug entrapment percent was determined. Drug release profiles, in media at different temperature and pH, depend on hydrogels crosslinking degree and drug–bead interactions. By using semi-empirical equations, the release mechanism was extensively studied and the diffusional contribute was evaluated
Synthesis of antioxidant polymers by grafting of gallic acid and catechin on gelatin
No full textA novel, simple, and cheap method to synthesize antioxidant-protein conjugates by grafting reaction was developedemploying a hydrogen peroxide-ascorbic acid pair as radical initiator system. Our challenge was to covalentlybind molecules with tested antioxidant activity, as gallic acid (GA) and catechin (CT) to a biomacromolecule, asgelatin, extensively used in the pharmaceutical, cosmetic, and food industry. In this way, two gelatin conjugates,bearing GA and CT covalently bounded to a side chain of protein, were synthesized. Calorimetric, UV-vis, andfluorescence analyses were performed to verify the covalent bond between antioxidant molecules and gelatin,and the antioxidant activity of conjugates was compared to that of a control polymer submitted to the samereaction conditions without antioxidant molecule. The ability of synthesized materials to inhibit 2,2′-diphenyl-1-picrylhydrazyl, hydroxyl radicals, and linoneic acid peroxidation was determined and, to well characterizedantioxidant properties of grafted biomacromolecules, disposable phenolic equivalents and total antioxidant activitywere calculated. The conjugates showed a good antioxidant activity, confirming the efficiency of the syntheticstrategy proposed in this paper. The results clearly showed that antioxidant moieties covalently bounded to anatural polymer allow to introduce in the macromolecule peculiar features for specific industrial applications.A novel, simple, and cheap method to synthesize antioxidant-protein conjugates by grafting reaction was developedemploying a hydrogen peroxide-ascorbic acid pair as radical initiator system. Our challenge was to covalentlybind molecules with tested antioxidant activity, as gallic acid (GA) and catechin (CT) to a biomacromolecule, asgelatin, extensively used in the pharmaceutical, cosmetic, and food industry. In this way, two gelatin conjugates,bearing GA and CT covalently bounded to a side chain of protein, were synthesized. Calorimetric, UV-vis, andfluorescence analyses were performed to verify the covalent bond between antioxidant molecules and gelatin,and the antioxidant activity of conjugates was compared to that of a control polymer submitted to the samereaction conditions without antioxidant molecule. The ability of synthesized materials to inhibit 2,2′-diphenyl-1-picrylhydrazyl, hydroxyl radicals, and linoneic acid peroxidation was determined and, to well characterizedantioxidant properties of grafted biomacromolecules, disposable phenolic equivalents and total antioxidant activitywere calculated. The conjugates showed a good antioxidant activity, confirming the efficiency of the syntheticstrategy proposed in this paper. The results clearly showed that antioxidant moieties covalently bounded to anatural polymer allow to introduce in the macromolecule peculiar features for specific industrial applications
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