Carboxymethyl cellulose/lignin blended films: physicochemical and antioxidant properties

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Natamycin-loaded poly(n-isopropylacrylamide) nanohydrogels for smart edible packaging : development and characterization

The development of new formulations for antimicrobial agents release has attracted great attention due to the possibility of using such formulations in several applications (e.g. food packaging and surface treatments in biomedical devices). Smart packaging appears in the last years as one of the most promissory application to food packaging in order to enhance the capacity to maintain food quality and safety. Moreover, edible packaging, using edible and biodegradable biopolymers, has been stated as one of the promises in packaging science (e.g. fresh-cut products, cheese, fruits, fish). Based on this and in the fact that no work has been reported with the incorporation of smart nanohydrogels in edible packaging, a smart delivery device consisting in poly(N-isopropylacrylamide) nanohydrogels and polysaccharide- based films was developed. Polysaccharide-based films with and without the incorporation of natamycin-loaded poly(N-isopropylacrylamide) nanohydrogels were charactherized in terms of: transport (water vapour, oxygen and carbon dioxide permeabilities) and mechanical properties (tensile strength and elongation-at-break), opacity, water sensitivity (moisture content and contact angle) and thermal properties (differential scanning calorimetry - DSC and thermogravimetric analyses - TGA). Chemical interactions were studied by means of Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy was used to verify the presence of nanohydrogel in the film matrix. [...

Characterization of PHBV films loaded with FO1 bacteriophage using polyvinyl alcohol-based nanofibers and coatings: a comparative study

There is a current demand for novel active food packaging solutions using biodegradable materials and no chemical antimicrobial compounds, to ensure food quality and safety. This work involved the incorporation of Salmonella Enteritidis bacteriophage Felix O1, for potential use as an anti-Salmonella agent, into polyvinyl alcohol (PVOH) coatings and fibers deposited by casting and electrospinning on polyhydroxybutyrate/polyhydroxyvalerate (PHBV) films. PHBV films (pristine, with coating, and with nanofibers) were characterized in terms of water sensitivity, mechanical performance, morphology, and thermal properties. Additionally, X-ray diffraction and Fourier Transform Infrared Spectroscopy were performed to assess possible chemical modifications on PHBV films after PVOH deposition and the presence of bacteriophage. PVOH increased the moisture content from 5.98% (PHBV) to 8.94% and 8.28% for PHBV/coating films and PHBV/nanofiber films respectively, increased the solubility from 0% (PHBV) to 30.32% (PHBV/coating films) and to 32.42% (PHBV/nanofiber films), and increased the hydrophilicity of the films (contact angle of 76.31° for PHBV, 64.01° for PHBV/coating films and 30.90° for PHBV/nanofiber films), leading to an increased water affinity of their surface. Felix O1 was successfully added and maintained antimicrobial activity (106 titer) after the formation of the coating and nanofibers, demonstrating that these solutions can potentially be used in future packaging materials to avoid Salmonella contamination.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/ BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER 006684). This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agree ment No 713640. Maria Jos´e Costa is recipient of a fellowship supported by a Doctoral Program (SFRH/BD/122897/2016) funded by the Portu guese Foundation for Science and Technology (FCT, POPH-QREN and FSE Portugal). All the bacteriophage solutions were kindly supplied by Micreos (Netherlands).info:eu-repo/semantics/publishedVersio

Use of edible films and coatings in cheese preservation: Opportunities and challenges

In the last years, there has been a growing interest in the use of edible materials in food packaging. The cheese industry is clearly one of the sectors where these materials have a good opportunity for application, as shown by the recent developments on edible coatings and films for cheese. Edible coatings and films, besides its edibility, can be used to reduce weight loss and prevent the microbiological spoilage through the control of oxygen and carbon dioxide exchange rate and as a carrier of antimicrobial compounds. This review summarizes the recent results on edible films and coatings for cheese, the main developments and the main future perspectives for the application of these materials in the cheese industry.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/ BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Maria José Costa is recipient of a fellowship supported by a doctoral program (SFRH/BD/122897/2016) funded by the Portuguese Foundation for Science and Technology (FCT, POPH-QREN and FSE Portugal).info:eu-repo/semantics/publishedVersio

Physico-chemical properties of alginate-based films: crosslinking and mannuronic/ guluronic ratio effect

São Paulo School of Advanced Sciences on Reverse Engineering of Processed Foods[Excerpt] Films can be produced by different edible materials such as: polysaccharides, protein, and lipids, with the possible addition of plasticizers and/or surfactants. Their performance is directly related with the material composition and the environmental conditions. Alginate films have been extensively studied, nevertheless their use in the production of edible films ask for the fully understanding of the effect of their main characteristics on the film’s final properties. This work aims to characterize alginatebased films (10 g/L), with different ratios of mannuronic (M) and guluronic (G) acids and cross linking with different concentrations of CaCl2 (0 to 15 g/L). [...]Maria José Costa is recipient of a fellowship supported by a doctoral program (SFRH/BD/122897/2016) funded by the Portuguese Foundation for Science and Technology (FCT, POPH-QREN and FSE Portugal).info:eu-repo/semantics/publishedVersio

Carboxymethyl cellulose-based films: Effect of organosolv lignin incorporation on physicochemical and antioxidant properties

Organosolv lignin was incorporated in carboxymethyl cellulose (CMC)-based films as a reinforcing and bioactive agent. Films were produced by the casting method using compatible and environmentally friendly solvents. The incorporation of lignin in CMC-based films was evaluated in term of morphology, physicochemical, barrier, mechanical and antioxidant properties. Solubility tests showed that lignin improved the water resistance of the films for approx. 60%. This behavior was also observed for the water vapor permeability, achieving a 20% reduction. Morphological characteristics suggested low compatibility between organosolv lignin and CMC matrix, revealed by the small aggregates homogeneously distributed in the film, through scanning electron microscopy, related to the self-assembly behavior of lignin. CMC/lignin-based films also presented higher thermal stability. Fourier transform infrared spectroscopy showed that incorporation of lignin led to small changes in the film's structure. Finally, organosolv lignin proved to be a promising material for the development of active CMC-based films due to its demonstrated antioxidant activity that can be useful to pack food products that suffer from undesirable oxidation reactions.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Nonlinear Thermopower Behaviour of N-Type Carbon Nanofibres and Their Melt Mixed Polypropylene Composites

The temperature dependent electrical conductivity σ (T) and thermopower (Seebeck coeffi-cient) S (T) from 303.15 K (30◦ C) to 373.15 K (100◦ C) of an as-received commercial n-type vapour grown carbon nanofibre (CNF) powder and its melt-mixed polypropylene (PP) composite with 5 wt.% of CNFs have been analysed. At 30◦ C, the σ and S of the CNF powder are ~136 S m−1 and −5.1 µV K−1, respectively, whereas its PP/CNF composite showed lower conductivities and less negative S-values of ~15 S m−1 and −3.4 µV K−1, respectively. The σ (T) of both samples presents a dσ/dT 0 character, also observed in some doped multiwall carbon nanotube (MWCNT) mats with nonlinear thermopower behaviour, and explained here from the contribution of impurities in the CNF structure such as oxygen and sulphur, which cause sharply varying and localized states at approximately 0.09 eV above their Fermi energy level (EF)

Physicochemical properties of alginate-based films: effect of ionic crosslinking and mannuronic and guluronic acid ratio

Abstract The use of alginates as films in food applications has increased in the recent years due to their swelling capacity and overall functionality. This behaviour is a result of their capacity to crosslink with Ca2+ ion. Aiming to fully understand the effect of calcium chloride (CaCl2) crosslinking and the mannuronic (M) and guluronic (G) acid ratio (M/G) of alginate structure in the films properties, alginate-based films with different (M/G) ratios were crosslinked at increasing CaCl2 concentrations. Films were produced by casting, and characterized in terms of mechanical properties (tensile strength and elongation-at-break), opacity, water sensitivity (moisture content, solubility and water vapour permeability) and morphology, evaluated by scanning electronic microscopy (SEM). Chemical interactions were studied by Fourier Transform Infrared Spectroscopy (FTIR) to assess possible chemical modifications of alginate-based films after crosslinking. Crosslinking significantly affected the alginate structure and properties, decreasing film thickness, moisture content, solubility and water vapour permeability of the alginate-based films. The mechanical properties were also influenced by the crosslinking and high CaCl2 concentrations lead to an increase of tensile strength. Results showed a relation between M/G ratios and CaCl2 concentrations and the resulting films properties. Alginate and the respective crosslinker should be chosen taking into account M/G ratio, since high contents of M residues lead to fragile and flexible films and high content of G residues to stronger films, and these properties are highly dependent on the concentration of CaCl2. Overall, alginate-based films are a good candidate to obtain tailored made edible films for food applications. Further investigation should be done to fully understand the effect of the alginate chain composition and order (e.g. MM, GG, GM, MG) in alginate-based films properties.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Maria José Costa is recipient of a fellowship supported by a doctoral program (SFRH/BD/122897/2016) funded by the Portuguese Foundation for Science and Technology (FCT, POPH-QREN and FSE Portugal). Sanna Sillankorva is Investigador FCT (IF/01413/2013). This research was supported by Norte Regional Operational Program 2014–2020 (Norte2020) through the European Regional Development Fund (ERDF) Nanotechnology based functional solutions (NORTE-01-0145-FEDER-000019).info:eu-repo/semantics/publishedVersio