Obtention of Antimicrobial Fibers Type Core/Shell PLA/PVOH-LAE by Coaxial Electrospinning

Coaxial electrospinning (EC) is a technology that allows the encapsulation of active compounds, as ethyl lauroyl arginate (LAE), in shell/core structures, in order to develop new antimicrobial food packaging materials with slowdown of active compound´s release with the purpose of extending food shelf life. For this reason, the objective of this study consisted in developing antimicrobial fibers shell/core type by EC. Two polymers with different hydrophilic character as poly (lactic acid) (PLA) to the shell and poly (vinyl alcohol) (PVOH) and LAE to the core were used to obtain PLA/PVOH-LAE fibers, and slowdown the release of antimicrobial compound. The morphology of fibers was evaluated by optical microscopy and the thermal properties through thermogravimetric analyses (TGA). Release studies were carried out in fatty (ETOH 95%) food simulant and was compared with the minimum inhibitory concentration (MIC) values of LAE against Listeria innnocua. The optical micrographs evidenced the obtention of shell/core structure with an average diameter of 0,6 µm approximately, and the TGA analyses demonstrated the thermal protection of LAE by shell of fibers. Released LAE reached the equilibrium state in ETOH 95% during the first 3 hours, maintaining a higher concentration than MIC value obtained in L. innnocua (10 ppm). The results demonstrate that new packaging materials with antimicrobial activity as PLA/PVOH-LAE polymeric fibers with shell/core structure can be obtained through coaxial electrospinning technique. Keywords: coaxial electrospinning, ethyl lauroyl arginate, fibers, shell/core, food packaging. Resumen El electrohilado coaxial (EC) es una tecnología que permite encapsular compuestos activos como el etil lauroil arginato (LAE) en estructuras tipo pared/núcleo con la finalidad de desarrollar nuevos materiales antimicrobianos para el envasado de alimentos que ralenticen la liberación del compuesto y extiendan la vida útil del alimento. Por tal razón, el objetivo de este estudio consistió en desarrollar fibras antimicrobianas tipo pared/núcleo mediante EC. Dos polímeros con distinto carácter hidrofílico como el poli (ácido láctico) (PLA) para la pared y poli (alcohol vinílico) (PVOH) y LAE para el núcleo se utilizaron para obtener las fibras PLA/PVOH-LAE, y ralentizar la liberación del compuesto antimicrobiano. La morfología de las fibras se evaluó mediante microscopía óptica y sus propiedades térmicas mediante análisis termogravimétricos (TGA). Se realizaron estudios de liberación del LAE en un simulante de alimentos graso (ETOH 95%), y se comparó con la concentración mínima inhibitoria (MIC) hacia una bacteria Gram positiva Listeria innnocua. Las micrografías ópticas evidenciaron la obtención de la estructura pared/núcleo con un diámetro promedio de 0,6 µm aproximadamente, y el análisis TGA demostró la protección térmica del LAE por la pared de las fibras. El LAE liberado alcanzó el estado de equilibrio en ETOH 95% durante las 3 hr iniciales, manteniendo una concentración superior a la MIC obtenida para L. innnocua (10 ppm). Los resultados demuestran que nuevos materiales de envase con actividad antimicrobiana como fibras poliméricas PLA/PVOH-LAE con estructura pared/núcleo pueden ser obtenidos mediante la técnica de electrohilado coaxial. Palabras clave: electrohilado coaxial, etil lauroil arginato, fibras, pared/núcleo, envase de alimentos

Obtention of Antimicrobial Fibers Type Core/Shell Pla/Pvoh-Lae By Coaxial Electrospinning

Coaxial electrospinning (EC) is a technology that allows the encapsulation of active compounds, such as ethyl lauroyl arginate (LAE), in shell/core structures, in order to develop new antimicrobial materials for food packaging that slow down the release of active compounds and extend the food’s shelf life. For this reason, the objective of this study was to develop antimicrobial fibers shell/core type by EC. Two polymers with different hydrophilic character, polylactic acid (PLA) for the shell and polyvinyl alcohol (PVOH) and LAE for the core, were used to obtain PLA/PVOH-LAE fibers and slow the release of the antimicrobial compound. The morphology of fibers was evaluated by optical microscopy and their thermal properties through thermogravimetric analyses (TGA). LAE release studies were carried out in a fatty food simulant (ETOH 95%), and was compared with the minimum inhibitory concentration (MIC) values of LAE against a gram-positive bacteria, Listeria innnocua. The optical micrographs showed the obtaining of the shell/core structure with an average diameter of approximately 0.6 µm, and the TGA analyses demonstrated the thermal protection of LAE by the shell of the fibers. Released LAE reached the equilibrium state in ETOH 95% during the first 3 hours, maintaining a higher concentration than the MIC value obtained in L. innnocua (10 ppm). The results demonstrate that new packaging materials with antimicrobial activity such as PLA/PVOH-LAE polymeric fibers with a shell/core structure can be obtained through the coaxial electrospinning technique. Keywords: coaxial electrospinning, ethyl lauroyl arginate, fibers, shell/core, food packaging. Resumen El electrohilado coaxial (EC) es una tecnología que permite encapsular compuestos activos como el etil lauroil arginato (LAE) en estructuras tipo pared/núcleo con la finalidad de desarrollar nuevos materiales antimicrobianos para el envasado de alimentos que ralenticen la liberación del compuesto y extiendan la vida útil del alimento. Por tal razón, el objetivo de este estudio consistió en desarrollar fibras antimicrobianas tipo pared/núcleo mediante EC. Dos polímeros con distinto carácter hidrofílico como el poli (ácido láctico) (PLA) para la pared y poli (alcohol vinílico) (PVOH) y LAE para el núcleo se utilizaron para obtener las fibras PLA/PVOH-LAE, y ralentizar la liberación del compuesto antimicrobiano. La morfología de las fibras se evaluó mediante microscopía óptica y sus propiedades térmicas mediante análisis termogravimétricos (TGA). Se realizaron estudios de liberación del LAE en un simulante de alimentos graso (ETOH 95%), y se comparó con la concentración mínima inhibitoria (MIC) hacia una bacteria Gram positiva Listeria innnocua. Las micrografías ópticas evidenciaron la obtención de la estructura pared/núcleo con un diámetro promedio de 0,6 µm aproximadamente, y el análisis TGA demostró la protección térmica del LAE por la pared de las fibras. El LAE liberado alcanzó el estado de equilibrio en ETOH 95% durante las 3 hr iniciales, manteniendo una concentración superior a la MIC obtenida para L. innnocua (10 ppm). Los resultados demuestran que nuevos materiales de envase con actividad antimicrobiana como fibras poliméricas PLA/PVOH-LAE con estructura pared/núcleo pueden ser obtenidos mediante la técnica de electrohilado coaxial. Palabras clave: electrohilado coaxial, etil lauroil arginato, fibras, pared/núcleo, envase de alimentos

La competencia social y el desarrollo de comportamientos cívicos: la labor orientadora del profesor

En este artículo se analiza el concepto de competencia social desde una óptica positiva y promotora de una convivencia de calidad, así como estimuladora de la formación socioemocional de los alumnos. En un primer momento se realiza una aproximación histórica al término “competencia social”, describiendo los principales cambios terminológicos y conceptuales experimentados en los últimos años. Una vez establecido el marco, se describe a la escuela como un contexto privilegiado donde tienen lugar gran parte de los aprendizajes sociales y donde se sientan las bases para la posterior integración y participación de los alumnos como ciudadanos que conviven y se relacionan con otros. Dentro de este contexto se ha decidido centrar la atención en la figura del profesor

Antimicrobial Properties of Ethylene Vinyl Alcohol/Epsilon-Polylysine Films and Their Application in Surimi Preservation

[EN] Polymer films based on ethylene vinyl copolymers (EVOH) containing a 29 % (EVOH 29) and a 44 % molar percentage of ethylene (EVOH 44), and incorporating epsilon-polylysine (EPL) at 0 %, 1 %, 5 % and 10 % were successfully made by casting. The optical properties and the amount of EPL released from the films to phosphate buffer at pH 7.5 were evaluated, films showing great transparency and those of EVOH 29 copolymer releasing a greater amount of EPL. The antimicrobial properties of the resulting films were tested in vitro against different foodborne microorganisms and in vivo in surimi sticks. With regard to the antimicrobial capacity tested in vitro in liquid medium at 37 A degrees C and 4 A degrees C against Listeria monocytogenes and Escherichia coli over a period of 72 h, films showed a considerable growth inhibitory effect against both pathogens, more notably against L. monocytogenes, and being EVOH 29 more effective than EVOH 44 films. At 37 A degrees C, total growth inhibition was observed for EVOH 29 films incorporating 10 % EPL against both microorganisms whereas the copolymer EVOH 44 did show total inhibition against L. monocytogenes and the growth of E. coli was reduced by 6.64 log units. At 4 A degrees C, no film was able to inhibit completely bacterial growth. Scanning electron microscopy micrographs showed corrugated cell surfaces with blisters and bubbles, and collapse of the cells appearing shorter and more compact after treatment with EPL. Finally, the films were successfully used to increase the shelf life of surimi sticks. The results show the films developed have a great potential for active food packaging applications.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, projects AGL2012-39920-C03-01, and fellowship funding for V. M.-G.Muriel-Galet, V.; Lopez-Carballo, G.; Gavara Clemente, R.; Hernández-Muñoz, P. (2014). Antimicrobial Properties of Ethylene Vinyl Alcohol/Epsilon-Polylysine Films and Their Application in Surimi Preservation. Food and Bioprocess Technology. 7(12):3548-3559. https://doi.org/10.1007/s11947-014-1363-1S35483559712Adams, M. R., & Moss, M. O. (2008). Food microbiology. UK: The Royal Society of Chemistry Cambridge.Aucejo, S., Catala, R., & Gavara, R. (2000). Interactions between water and EVOH food packaging films. Food Science and Technology International, 6(2), 159–164.Brandt, A. L., Castillo, A., Harris, K. B., Keeton, J. T., Hardin, M. D., & Taylor, T. M. (2010). Inhibition of Listeria monocytogenes by food antimicrobials applied singly and in combination. Journal of Food Science, 75(9), 557–563.Buchanan, R. L., & Doyle, M. P. (1997). Foodborne disease significance of Escherichia coli O157:H7 and other enterohemorrhagic E-coli. Food Technology, 51(10), 69–76.Chang, S.-S., Lu, W.-Y. W., Park, S.-H., & Kang, D.-H. (2010). Control of foodborne pathogens on ready-to-eat roast beef slurry by epsilon-polylysine. International Journal of Food Microbiology, 141(3), 236–241.Chang, Y., McLandsborough, L., & McClements, D. J. (2012). Cationic antimicrobial (epsilon-polylysine)-anionic polysaccharide (Pectin) interactions: influence of polymer charge on physical stability and antimicrobial efficacy. Journal of Agricultural and Food Chemistry, 60(7), 1837–1844.Chi-Zhang, Y. D., Yam, K. L., & Chikindas, M. L. (2004). Effective control of Listeria monocytogenes by combination of nisin formulated and slowly released into a broth system. International Journal of Food Microbiology, 90(1), 15–22.Coton, M., Denis, C., Cadot, P., & Coton, E. (2011). Biodiversity and characterization of aerobic spore-forming bacteria in surimi seafood products. Food Microbiology, 28(2), 252–260.FAO (2005) Further processing of fish Fisheries and Aquaculture Department, Rome. Updated 27 May 2005 Retrieved 14 March 2011.FDA (2004) Agency reponse letter GRAS Notice No. GRN 00135.Gambarin, P., Magnabosco, C., Losio, M. N., Pavoni, E., Gattuso, A., Arcangeli, G., et al. (2012). Listeria monocytogenes in ready-to-rat seafood and potential hazards for the consumers. International Journal of Microbiology, 2012, 497–635.Geornaras I, Yoon Y., Belk K. E., Smith G. C., Sofos J. N. (2007). Antimicrobial activity of epsilonpolylysine against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in various food extracts. Journal of Food Science, 72(8), M330–4.Gunlu, A., & Koyun, E. (2013). Effects of vacuum packaging and wrapping with chitosan-based edible film on the extension of the shelf life of sea bass (Dicentrarchus labrax) fillets in cold storage (4 A degrees C). Food and Bioprocess Technology, 6(7), 1713–1719.Hiraki, J. (1995). Basic and applied studies on ε-polylysine. Journal of Antibacterial Antifungal Agents Japan, 23, 349–493.Hiraki, J. (2000). ε-Polylysine, its development and utilization. Fine Chemistry, 29, 18–25.Hiraki, J., Ichikawa, T., Ninomiya, S., Seki, H., Uohama, K., Kimura, S., et al. (2003). Use of ADME studies to confirm the safety of epsilon-polylysine as a preservative in food. Regulatory Toxicology and Pharmacology, 37(2), 328–340.Ho, Y. T., Ishizaki, S., & Tanaka, M. (2000). Improving emulsifying activity of epsilon-polylysine by conjugation with dextran through the Maillard reaction. Food Chemistry, 68(4), 449–455.Huss, H. H., Jorgensen, L. V., & Vogel, B. F. (2000). Control options for Listeria monocytogenes in seafoods. International Journal of Food Microbiology, 62(3), 267–274.Kaneko, K., Hayashidani, H., Ohtomo, Y., Kosuge, J., Kato, M., Takahashi, K., et al. (1999). Bacterial contamination of ready-to-eat foods and fresh products in retail shops and food factories. Journal of Food Protection, 62(6), 644–649.Kang, E. T., Tan, K. L., Kato, K., Uyama, Y., & Ikada, Y. (1996). Surface modification and functionalization of polytetrafluoroethylene films. Macromolecules, 29(21), 6872–6879.Li, J., Han, Q., Chen, W., & Ye, L. (2012). Antimicrobial activity of Chinese bayberry extract for the preservation of surimi. Journal of the Science of Food and Agriculture, 92(11), 2358–2365.Lopez de Dicastillo, C., Nerin, C., Alfaro, P., Catala, R., Gavara, R., & Hernandez-Munoz, P. (2011). Development of new antioxidant active packaging films based on ethylene vinyl alcohol copolymer (EVOH) and green tea extract. Journal of Agricultural and Food Chemistry, 59(14), 7832–7840.Lopez-de-Dicastillo, C., Alonso, J. M., Catala, R., Gavara, R., & Hernandez-Munoz, P. (2010). Improving the antioxidant protection of packaged food by incorporating natural flavonoids into ethylene-vinyl alcohol copolymer (EVOH) dilms. Journal of Agricultural and Food Chemistry, 58(20), 10958–10964.Lopez-de-Dicastillo, C., Pezo, D., Nerin, C., Lopez-Carballo, G., Catala, R., Gavara, R., et al. (2012). Reducing oxidation of foods through antioxidant active packaging based on ethyl vinyl alcohol and natural flavonoids. Packaging Technology and Science, 25(8), 457–466.M100-S22 (2012) Performance Standards for Antimicrobial Susceptibility Testing: Eighteenth Informational Supplement. Clinical and Laboratory Standards Institute. Advancing Quality in Health Care Testing. Vol. 32 No. 3. Replaces M100-S21 . Vol. 31 No. 1Mead, P. S., & Griffin, P. M. (1998). Escherichia coli O157:H7. Lancet, 352(9135), 1207–1212.Miya, S., Takahashi, H., Ishikawa, T., Fujii, T., & Kimura, B. (2010). Risk of Listeria monocytogenes xontamination of raw ready-to-eat seafood products available at retail outlets in Japan. Applied and Environmental Microbiology, 76(10), 3383–3386.Muriel-Galet, V., Cerisuelo, J. P., Lopez-Carballo, G., Lara, M., Gavara, R., & Hernandez-Munoz, P. (2012a). Development of antimicrobial films for microbiological control of packaged salad. International Journal of Food Microbiology, 157(2), 195–201.Muriel-Galet, V., Lopez-Carballo, G., Gavara, R., & Hernandez-Munoz, P. (2012b). Antimicrobial food packaging film based on the release of LAE from EVOH. International Journal of Food Microbiology, 157(2), 239–244.Muriel-Galet, V., Cerisuelo, J. P., Lopez-Carballo, G., Aucejo, S., Gavara, R., & Hernandez-Munoz, P. (2013a). Evaluation of EVOH-coated PP films with oregano essential oil and citral to improve the shelf-life of packaged salad. Food Control, 30(1), 137–143.Muriel-Galet, V., López-Carballo, G., Hernández-Muñoz, P., & Gavara, R. (2013b). Characterization of ethylene–vinyl alcohol copolymer containing lauril arginate (LAE) as material for active antimicrobial food packaging. Food Packaging and Shelf Life, 1, 10–17.Park, J. W. (2014). Surimi and surimi seafood. Boca Raton: CRC Press.Shima, S., & Sakai, H. (1977). Polylysine produced by Streptomyces. Agricultural and Biological Chemistry, 41(9), 1807–1809.Shima, S., Matsuoka, H., Iwamoto, T., & Sakai, H. (1984). Antimicrobial action of epsilon-poly-l-lysine. Journal of Antibiotics, 37(11), 1449–1455.Singh, R. K., & Balange, A. K. (2005). Characteristics of pink perch (Nemipterus japonicus) surimi at frozen temperature. Journal of Food Processing and Preservation, 29(1), 75–83.Suppakul, P., Miltz, J., Sonneveld, K., & Bigger, S. W. (2003). Active packaging technologies with an emphasis on antimicrobial packaging and its applications. Journal of Food Science, 68(2), 408–420.Ting, H. Y., Ishizaki, S., & Tanaka, M. (1999). Epsilon-polylysine improves the quality of surimi products. Journal of Muscle Foods, 10(4), 279–294.Tzschoppe, M., Martin, A., & Beutin, L. (2012). A rapid procedure for the detection and isolation of enterohaemorrhagic Escherichia coli (EHEC) serogroup O26, O103, O111, O118, O121, O145 and O157 strains and the aggregative EHEC O104:H4 strain from ready-to-eat vegetables. International Journal of Food Microbiology, 152(1–2), 19–30.Uchida, E., Uyama, Y., & Ikada, Y. (1993). Sorption of low-molecular-weight anions into thin polycation layers grafted onto a film. Langmuir, 9(4), 1121–1124.Unalan, I. U., Ucar, K. D. A., Arcan, I., Korel, F., & Yemenicioglu, A. (2011). Antimicrobial potential of polylysine in edible films. Food Science and Technology Research, 17(4), 375–380.Venugopal, V., & Shahidi, F. (1995). Value-added products from underutilized fish species. Critical Reviews in Food Science and Nutrition, 35(5), 431–453.Zambuchini, B., Fiorini, D., Verdenelli, M. C., Orpianesi, C., & Ballini, R. (2008). Inhibition of microbiological activity during sole (Solea solea L.) chilled storage by applying ellagic and ascorbic acids. LWT--Food Science and Technology, 41(9), 1733–1738.Zinoviadou, K. G., Koutsoumanis, K. P., & Biliaderis, C. G. (2010). Physical and thermo-mechanical properties of whey protein isolate films containing antimicrobials, and their effect against spoilage flora of fresh beef. Food Hydrocolloids, 24(1), 49–59

Mathematical modeling of gallic acid release from chitosan films with grape seed extract and carvacrol

Controlled release of antimicrobial and antioxidant compounds from packaging films is of utmost importance for extending the shelf-life of perishable foods. This study focused on the mathematical modeling of gallic acid release into an aqueous medium from three chitosan films, formulated with grape seed extract (GSE) and carvacrol. We quantified the release by HPLC technique during 30days at three temperatures (5, 25 and 45°C). The diffusion coefficients, varying with temperature according to an Arrhenius-type relationship, and the respective activation energies for Film-1 and Film-2 were, respectively [Formula: see text] m2s-1 and [Formula: see text] m2s-1, Ea1=58kJmol-1 and Ea2=60kJmol-1 as obtained from the Fickian fit. The low concentrations of gallic acid released by Film-3 could not be detected by HPLC, therefore the respective diffusion coefficient was not estimated. This study will help with the development and optimization of active packaging (AP) films aiming at improved food preservation and shelf-life extension.Javiera F. Rubilar gratefully acknowledges her Ph.D. grant from ErasmusMundus 2008-1022/001 Frame ECW/17, EACEA(European Union), financial support of the Fondecyt-Postdoctoral #3140349 project from CONICYT, and also “Dirección de Investigación e Innovación Escuela de Ingeniería” at Pontificia Universidad Católica de Chile. Rui M. S. Cruz acknowledges grant SFRH/BPD/70036/2010 from Fundac¸ ão para a Ciência e Tecnologia, Portugalinfo:eu-repo/semantics/publishedVersio

Influence of homogenization conditions on physical properties and antioxidant activity of fully biodegradable pea protein-alpha-tocopherol films

In this study, antioxidant biodegradable films based on pea protein and alpha-tocopherol were successfully developed by solution casting. The effect of both the homogenization conditions (rotor stator and microfluidizer) and the relative humidity (RH) on the microstructure and physical properties (transparency, tensile, oxygen and water vapour barrier properties) of pea protein/alpha-tocopherol-based films was evaluated. The addition of alpha-tocopherol produced minimal changes in the films transparency, while providing them with antioxidant properties and improved water vapour and oxygen barrier properties (up to 30 % in both water vapour and oxygen permeability) when films were at low and intermediate RH. The addition of alpha-tocopherol in microfluidized films gave rise to an increase in their resistance to break and extensibility (up to 27 % in E values) at intermediate and high RH. These results add a new insight into the potential of employing pea protein and alpha-tocopherol in the development of fully biodegradable antioxidant films which are of interest in food packagingThe authors acknowledge the financial support from the Spanish Ministerio de Educacion y Ciencia throughout the project AGL2010-20694, co-funded by FEDER. Author M.J.Fabra is a recipient of a Juan de la Cierva contract from the Spanish Ministerio de Economia y Competitividad.Fabra, MJ.; Jiménez, A.; Talens Oliag, P.; Chiralt, A. (2014). Influence of homogenization conditions on physical properties and antioxidant activity of fully biodegradable pea protein-alpha-tocopherol films. Food and Bioprocess Technology. 7(12):3569-3578. https://doi.org/10.1007/s11947-014-1372-0S35693578712ASTM (1995). Standard test methods for water vapor transmission of materials. Standards Desingnations: E96-95. In: Annual Book of ASTM Standards (pp. 406-413); American Society for Testing and Materials: Philadelphia, PA.ASTM (2001). Standard test method for tensile properties of thin plastic sheeting. Standard D882. In: Annual book of American Standard Testing Methods (pp 162-170). D882. Philadelphia:ASTM.Bertan, L. C., Tanada-Palmu, P. S., Siani, A. C., & Grosso, C. R. F. (2005). Effect of fatty acids and “Brazilian elemi” on composite films based on gelatin. Food Hydrocolloids, 19(1), 73–82.Byun, Y., Kim, Y. T., & Whiteside, S. (2010). Characterization of an antioxidant polylactic acid (PLA) film prepared with alpha-tocopherol, BHT and polyethylene glycol using film cast extruder. Journal of Food Engineering, 100, 239–244.Cerqueira, M. A., Costa, M. J., Fuciños, C., Pastrana, L. M., & Vicente, A. A. (2014). Development of active and nanotechnology-based smart edible packaging systems: physical-chemical characterization. Food and Bioprocess Technology, 7(5), 1472–1482.Choi, W. S., & Han, J. H. (2001). Physical and mechanical properties of pea–protein-based edible films. Journal of Food Science, 66, 319–322.Choi, W. S., & Han, J. H. (2002). Film-forming mechanism and heat denaturation effects on the physical and chemical properties of pea-protein-isolate edible films. Journal of Food Science, 67, 1399–1406.Fabra, M. J., Talens, P., & Chiralt, A. (2009). Microstructure and optical properties of sodium caseinate films containing oleic acidebeeswax mixtures. Food Hydrocolloids, 23, 676–683.Fabra, M. J., Talens, P., & Chiralt, A. (2010). Water sorption isotherms and phase transitions of sodium caseinate–lipid films as affected by lipid interactions. Food Hydrocolloids, 24, 384–391.Fabra, M. J., Hambleton, A., Talens, P., Debeaufort, F., & Chiralt, A. (2011). Effect of ferulic acid and α-tocopherol antioxidants on properties of sodium caseinate edible films. Food Hydrocolloids, 25, 1441–1447.Fabra, M. J., Talens, P., Gavara, R., & Chiralt, A. (2012). Barrier properties of sodium caseinate films as affected by lipid composition and moisture content. Journal of Food Engineering, 109, 372–379.Frankel, E. N., Huang, S. W., Kanner, J., & German, J. B. (1994). Interfacial phenomena in the evaluation of antioxidants: bulk oils vs emulsions. Journal of Agriculture and Food Chemistry, 42(5), 1054–1059.Gómez-Estaca, J., Giménez, B., Montero, P., & Gómez-Guillén, M. C. (2009). Incorporation of antioxidant borage extract into edible films based on sole skin gelatin or a commercial fish gelatin. Journal of Food Engineering, 92, 78–85.Huang, S. W., Frankel, E. N., & German, J. B. (1994). Antioxidant activity of alpha.- and.gamma.-tocopherols in bulk oils and in oil-in-water emulsions. Journal of Agriculture and Food Chemistry, 42(10), 2108–2114.Hutchings, J. B. (1999). Food and colour appearance (2nd ed.). Gaithersburg: Chapman and Hall Food Science Book, Aspen Publication.Jiménez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2010). Effect of lipid self-association on the microstructure and physical properties of hydroxypropylmethylcellulose edible films containing fatty acids. Carbohydrate Polymers, 82(3), 585–593.Jiménez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2013). Physical properties and antioxidant capacity of starch-sodium caseinate films containing lipids. Journal of Food Engineering, 116(3), 695–702.Jung, M. Y., & Min, D. B. (1990). Effects of alpha-. γ-, and δ-tocopherols on oxidative stability of soybean oil. Journal of Food Science, 55(5), 1464–1465.López-de-Dicastillo, C., Alonso, J. M., Catalá, R., Gavara, R., & Hernández-Muñoz, P. (2010). Improving the antioxidant protection of packaged food by incorporating natural flavonoids into ethylene-vinyl alcohol copolymer (EVOH) films. Journal of Agricultural and Food Chemistry, 58, 10958–10964.Ma, W., Tang, C.-H., Yin, S.-W., Yang, X. Q., Qi, J. R., & Xia, N. (2012). Effect of homogenization conditions on properties of gelatin-olive oil composite films. Journal of Food Engineering, 113(1), 136–142.Mauer, L. J., Smith, D. E., & Labuza, T. P. (2000). Water vapor permeability, mechanical, and structural properties of edible β-casein films. International Dairy Journal, 10(5–6), 353–358.Mc Hugh, T. H., Avena-Bustillos, R., & Krochta, J. M. (1993). Hydrophobic edible films:modified procedure for water vapor permeability and explanation of thickness effects. Journal of Food Science, 58(4), 899–903.McHugh, T. H., & Krochta, J. M. (1994). Dispersed phase particle size effects on water vapour permeability of whey protein–beeswax emulsion films. Journal of Food Processing and Preservation, 18, 173–188.Ozkan, G., Simsek, B., & Kuleasan, H. (2007). Antioxidant activities of Satureja cilicica essential oil in butter and in vitro. Journal of Food Engineering, 79, 1391–1396.Pereira de Abreu, D. A., Paseiro Losada, P., Maroto, J., & Cruz, J. M. (2011). Natural antioxidant active packaging film and its effect on lipid damage in frozen blue shark (Prionace glauca). Innovative Food Science and Emerging Technologies, 12, 50–55.Re, R., Pellegrini, N., Proteggente, A., Pannala, A., Yang, M., & Rice-Evans, C. (1999). Antioxidant activity applying an improved ABTS radical cation decoloration assay. Free Radical Biology and Medicine, 26, 1231–1237.Roos, Y. H. (1995). Phase transitions in food. San Diego: Academic Press.Salgado, P. R., Molina Ortiz, S. E., Petruccelli, S., & Mauri, A. N. (2010). Biodegradable sunflower protein films naturally activated with antioxidant compounds. Food Hydrocolloids, 24(5), 525–533.Salgado, P. R., Fernández, G. B., Drago, S. R., & Mauri, A. N. (2011). Addition of bovine plasma hydrolysates improves the antioxidant properties of soybean and sunflower protein-based films. Food Hydrocolloids, 25, 1433–1440.Samaranayaka, A. G. P., & Li-Chan, E. C. Y. (2008). Autolysis-assisted production of fish protein hydrolysates with antioxidant properties form Pacific hake (Merluccius productus). Food Chemistry, 107, 768–776.Souza, B. W. S., Cerqueira, A., Casariego, A., Lima, A. M. P., Teixeira, J. A., & Vicente, A. A. (2009). Effect of moderate electric fields in the permeation properties of chitosan coatings. Food Hydrocolloids, 23, 2110–2115

Development of a sustainable and antibacterial food packaging material based in a biopolymeric multilayer system composed by polylactic acid, chitosan, cellulose nanocrystals and ethyl lauroyl arginate

Biodegradable packaging materials with antimicrobial properties are main key for developing sustainable active packages able to protect different foodstuff. Thus, the aim of this research was developing a biopolymeric and antibacterial packaging material with a trilayer structure through the combination of extrusion, electrospinning and coating techniques. This trilayer system was composed by a support extruded layer of polylactic acid (PLA), an intermediate PLA electrospun layer loaded with ethyl lauroyl arginate (LAE) and cellulose nanocrystals (CNC), and a third inner chitosan coating. Morphological, wettability, antibacterial and disintegrability properties of this material were evaluated. The morphological surface analysis evidenced the heterogeneity of the chitosan coating over the electrospun PLA layer, and this effect affected negatively the evaluation of wettability of this trilayer material. Antibacterial assays evidenced a fast and strong bactericidal effect against Gram(+) and (−) bacteria that maintained this activity for 15 days. Finally, the biodegradable properties of different layers favored the disintegration of developed trilayer material at 21 days under composting conditions.The authors acknowledge the financial support of Spanish Research Agency through RYC2020-029874-I/AEI/10.13039/501100011033 and the Agencia Nacional de Investigación y Desarrollo de Chile (ANID) through the Fondecyt Regular Project no. 1200766, the Doctoral Scholarship CONICYT-PFCHA/Doctorado Nacional/2019-21190316, the “Programa de Financiamiento Basal para Centros Científicos y Tecnológicos de Excelencia” (Project AFB220001).Peer reviewe

Estudio de creencias, actitudes y actuaciones del profesorado en torno a la educación para la convivencia a través del cuestionario de "competencia social para el profesorado"

En este trabajo se presenta un instrumento de evaluación destinado a recoger las creencias, actitudes y actuaciones de los docentes a la hora de fomentar la competencia social y la educación para la convivencia dentro de sus aulas. Es fundamental abordar esta cuestión, puesto que la sensibilización y motivación que los docentes tengan hacia este tema influirá en su práctica diaria, en la forma de resolver los conflictos, en el clima del aula y en los vínculos que establezcan con los alumnos. Además, el estudio de la situación real del profesorado es un paso previo a la programación de actividades formativas. Finalmente, a esto debemos añadir que no son muchos los estudios de este tipo de nuestro país.The aim of this paper is to present an assessment tool for collecting information about the beliefs, attitudes and actions of teachers in promoting social competence and education for living together in theri classrooms. It is essential to addreaa this issue because, as educational professionals, we assume that teachers are key socializing agents for change and educational improvement. The awareness and motivation that they have toward this issue will influence ther daily practice, on how to resolve conflicts in the classroom climate and establish ties with students. Moreover, the study of the actual situation of teachers is a prerequisite to the scheduling of actiuvities. Finally, we should add that there are not many studies of this kind in our country

Estudio de creencias, actitudes y actuaciones del profesorado en torno a la educación para la convivencia a través del cuestionario de "competencia social para el profesorado"

En este trabajo se presenta un instrumento de evaluación destinado a recoger las creencias, actitudes y actuaciones de los docentes a la hora de fomentar la competencia social y la educación para la convivencia dentro de sus aulas. Es fundamental abordar esta cuestión, puesto que la sensibilización y motivación que los docentes tengan hacia este tema influirá en su práctica diaria, en la forma de resolver los conflictos, en el clima del aula y en los vínculos que establezcan con los alumnos. Además, el estudio de la situación real del profesorado es un paso previo a la programación de actividades formativas. Finalmente, a esto debemos añadir que no son muchos los estudios de este tipo de nuestro país.The aim of this paper is to present an assessment tool for collecting information about the beliefs, attitudes and actions of teachers in promoting social competence and education for living together in theri classrooms. It is essential to addreaa this issue because, as educational professionals, we assume that teachers are key socializing agents for change and educational improvement. The awareness and motivation that they have toward this issue will influence ther daily practice, on how to resolve conflicts in the classroom climate and establish ties with students. Moreover, the study of the actual situation of teachers is a prerequisite to the scheduling of actiuvities. Finally, we should add that there are not many studies of this kind in our country

Developing Post-Consumer Recycled Flexible Polypropylene and Fumed Silica-Based Nanocomposites with Improved Processability and Thermal Stability

Collection and mechanical recycling of post-consumer flexible polypropylene packaging is limited, principally due to polypropylene being very light-weight. Moreover, service life and thermal-mechanical reprocessing degrade PP and change its thermal and rheological properties according to the structure and provenance of recycled PP. This work determined the effect of incorporating two fumed nanosilica (NS) types on processability improvement of post-consumer recycled flexible polypropylene (PCPP) through ATR-FTIR, TGA, DSC, MFI and rheological analysis. Presence of trace polyethylene in the collected PCPP increased the thermal stability of the PP and was significantly maximized by NS addition. The onset decomposition temperature raised around 15 °C when 4 and 2 wt% of a non-treated and organically modified NS were used, respectively. NS acted as a nucleating agent and increased the crystallinity of the polymer, but the crystallization and melting temperatures were not affected. The processability of the nanocomposites was improved, observed as an increase in viscosity, storage and loss moduli with respect to the control PCPP, which were deteriorated due to chain scission during recycling. The highest recovery in viscosity and reduction in MFI were found for the hydrophilic NS due to a greater impact of hydrogen bond interactions between the silanol groups of this NS and the oxidized groups of the PCPP.The authors acknowledge the “Ramon y Cajal” Fellowship RYC2020-029874-I financed by the Spanish Ministry of Science and Innovation, the “Programa de Financiamiento Basal para Centros Científicos y Tecnológicos de Excelencia” (Project AFB220001) and the Directorate of Scientific and Technological Research of the University of Santiago, Chile (DICYT-USACH).With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2021-001189-S).Peer reviewe