125 research outputs found
Oxygen, water and sodium chloride transport in Soft Contact Lenses Materials
[EN] Oxygen permeability, diffusion coefficient of the sodium ions and water flux and permeability in different conventional hydrogel (Hy) and silicone-hydrogel (Si-Hy) contact lenses have been measured experimentally. The results showed that oxygen permeability and transmissibility requirements of the lens have been addressed through the use of siloxane containing hydrogels. In general, oxygen and sodium chloride permeability values increased with the water content of the lens but there was a percolation phenomenon from a given value of water uptake mainly in the Si-Hy lenses which appeared to be related with the differences between free water and bound water contents. The increase of ion permeability with water content did not follow a unique trend indicating a possible dependence of the chemical structure of the polymer and character ionic and non-ionic of the lens. Indeed, the salt permeability values for silicone hydrogel contact lenses were one order of magnitude below those of conventional hydrogel contact lenses, which can be explained by a diffusion of sodium ions occurring only through the hydrophilic channels. The increase of the ionic permeability in Si-Hy materials may be due to the confinement of ions in nanoscale water channels involving possible decreased degrees of freedom for diffusion of both water and ions. In general, ionic lenses presented values of ionic permeability and diffusivity higher than most non-ionic lenses. The tortuosity of the ionic lenses is lower than the non-ionic Si-Hy lenses. Frequency 55 and PureVision exhibited the highest water permeability and flux values and, these parameters were greater for ionic Si-Hy lenses than for ionic conventional hydrogel lenses.Gavara, R.; Compañ Moreno, V. (2016). Oxygen, water and sodium chloride transport in Soft Contact Lenses Materials. Journal of Biomedical Materials Research Part B Applied Biomaterials. 105(8):2218-2231. doi:10.1002/jbm.b.33762S22182231105
Randomized heuristics for the Capacitated Clustering Problem
In this paper, we investigate the adaptation of the Greedy Randomized Adaptive Search Procedure (GRASP) and Iterated Greedy methodologies to the Capacitated Clustering Problem (CCP). In particular, we focus on the effect of the balance between randomization and greediness on the performance of these multi-start heuristic search methods when solving this NP-hard problem. The former is a memory-less approach that constructs independent solutions, while the latter is a memory-based method that constructs linked solutions, obtained by partially rebuilding previous ones. Both are based on the combination of greediness and randomization in the constructive process, and coupled with a subsequent local search phase. We propose these two multi-start methods and their hybridization and compare their performance on the CCP. Additionally, we propose a heuristic based on the mathematical programming formulation of this problem, which constitutes a so-called matheuristic. We also implement a classical randomized method based on simulated annealing to complete the picture of randomized heuristics. Our extensive experimentation reveals that Iterated Greedy performs better than GRASP in this problem, and improved outcomes are obtained when both methods are hybridized and coupled with the matheuristic. In fact, the hybridization is able to outperform the best approaches previously published for the CCP. This study shows that memory-based construction is an effective mechanism within multi-start heuristic search techniques
Food aroma mass transport properties in renewable hydrophilic polymers
[EN] The sorption and transport properties of gliadin and chitosan films with respect to four representative food aroma components (ethyl caproate, 1-hexanol, 2-nonanone and α-pinene) have been studied under dry and wet environmental conditions. The partition coefficients (K) of the selected volatiles were also obtained using isooctane and soybean oil as fatty food simulants. The results showed that gliadin and chitosan films have very low capacities for the sorption of volatile compounds, and these capacities are influenced by the nature of the sorbate, the environmental relative humidity and the presence of glycerol as a plasticizer in the polymeric matrix. The volatile compounds also present a low partitioning in the biopolymer film/food stimulant system. Given the low levels of interaction observed with the volatiles, gliadin and chitosan films are of potential interest for the packaging of foods in which aroma is one of the most important quality attributes
Highlights
► Sorption kinetics and equilibrium partitioning of food aroma compounds in bioplastics. ► Gliadin and chitosan films show low sorption and partitioning capacities of food aroma compounds. ► Sorption and diffusion depend on volatile chemical structure, film composition and moisture. ► Great potential in packaging of foods in which aroma is an important quality attribute.This research has been supported from the Spanish Ministry of Science and Innovation through the Projects AGL2006-02176, AGL2009-08776 and FUN-C-FOOD Consolider Ingenio. The authors would like to thank A.P. Mac Cabe for critical reading of the manuscript.Balaguer, MP.; Gavara Clemente, R.; Hernández Muñoz, P. (2012). Food aroma mass transport properties in renewable hydrophilic polymers. Food Chemistry. 130(4):814-820. https://doi.org/10.1016/j.foodchem.2011.07.052S814820130
Multi-start methods for the capacitated clustering problem
In this work, we investigate the adaptation of the Greedy Randomized Adaptive Search Procedure (GRASP) and Iterated Greedy methodologies to the Capacitated Clustering Problem (CCP). In particular, we focus on the effect of the balance between randomization and greediness on the performance of these multi-start heuristic search methods when solving this NP-hard problem. The former is a memory-less approach that constructs independent solutions, while the latter is a memory-based method that constructs linked solutions, obtained by partially rebuilding previous ones. Both are based on the combination of greediness and randomization in the constructive process, and coupled with a subsequent local search phase
Antimicrobial Effectiveness of Lauroyl Arginate Incorporated into Ethylene Vinyl Alcohol Copolymers to Extend the Shelf-Life of Chicken Stock and Surimi Sticks
[EN] This study was designated to determine the antimicrobial effect of ethyl-N-alpha-dodecanoyl-l-arginate hydrochloride (LAE) incorporated into ethylene vinyl alcohol copolymers (EVOH) films on chicken stock and ready-to-eat surimi sticks. Firstly, the effect of LAE against Listeria monocytogenes and Escherichia coli was studied by using flow cytometry and scanning electron microscopy. Next, film-forming solutions of ethylene vinyl alcohol copolymers EVOH29 and EVOH44 (29 and 44 % molar percentage of ethylene, respectively) containing 0, 5 and 10 % w/w of LAE were cast into films. Several experiments were conducted to determine the antimicrobial activity of the films in vitro and also in vivo with the above-mentioned food products. The outcome of the tests showed a high impact on the viability of bacteria treated with LAE, with dramatic damage to the membrane. The films were able to inhibit the microbiota of the food products studied for 10 days under storage at 4 A degrees C, showing a significant antibacterial effect against L. monocytogenes and E. coli. These films show great potential as systems for sustained release of active molecules to improve the safety and quality of packaged food products.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, project AGL2012-39920-C03-01, and fellowship funding for V. M.-G.Muriel Galet, V.; Lopez-Carballo, G.; Gavara Clemente, R.; Hernández-Muñoz, P. (2015). Antimicrobial Effectiveness of Lauroyl Arginate Incorporated into Ethylene Vinyl Alcohol Copolymers to Extend the Shelf-Life of Chicken Stock and Surimi Sticks. Food and Bioprocess Technology. 8(1):208-216. https://doi.org/10.1007/s11947-014-1391-xS20821681Adams MR & Moss MO (2008) Food microbiology. The Royal Society of Chemistry Cambrigde, UKAppendini, P., & Hotchkiss, J. H. (2002). Review of antimicrobial food packaging. Innovative Food Science and Emerging Technologies, 3(2), 113–126.Bakal G & Diaz A (2005) The lowdown on lauric arginate. Food quality(Feb./March), 60-61.Fellows PJ (2009) Food processing technology: principle and practice. Third edn.Guo, M., Jin, T., Wang, L., Scullen, O. J., & Sommers, C. (2014). Antimicrobial films and coatings for inactivation of Listeria innocua on ready-to-eat deli turkey meat. Food Control, 40, 64–70.Han JH (2013) Innovations in food packaging.Hawkins, D. R., Rocabayera, X., Ruckman, S., Segret, R., & Shaw, D. (2009). Metabolism and pharmacokinetics of ethyl N-alpha-lauroyl-L-arginate hydrochloride in human volunteers. Food and Chemical Toxicology, 47(11), 2711–2715.Higueras, L., Lopez Carballo, G., Hernandez Munoz, P., Gavara, R., Rollini, M., López Carballo, G., & Hernández Muñoz, P. (2013). Development of a novel antimicrobial film based on chitosan with LAE (ethyl-N)-dodecanoyl-l-arginate) and its application to fresh chicken. International Journal of Food Microbiology, 165(3), 339–345.Kilcast D & Subramaniam P (2000) The stability and shelf-life of food. Woodhead Publishing CambridgeMuriel-Galet, V., Lopez-Carballo, G., Gavara, R., & Hernandez-Munoz, P. (2012). Antimicrobial food packaging film based on the release of LAE from EVOH. International Journal of Food Microbiology, 157(2), 239–244.Muriel-Galet, V., López-Carballo, G., Hernández-Muñoz, P., & Gavara, R. (2013). 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.Rodriguez, E., Seguer, J., Rocabayera, X., & Manresa, A. (2004). Cellular effects of monohydrochloride of L-arginine, N-alpha-lauroyl ethylester (LAE) on exposure to Salmonella typhimurium and Staphylococcus aureus. Journal of Applied Microbiology, 96(5), 903–912.Sallam, & Ibrahim, K. (2007). Antimicrobial and antioxidant effects of sodium acetate, sodium lactate, and sodium citrate in refrigerated sliced salmon. Food Control, 18(5), 566–575.Sung, S.-Y., Sin, L. T., Tee, T.-T., Bee, S.-T., Rahmat, A. R., Rahman, W. A. W. A., Tan, A.-C., & Vikhraman, M. (2013). Antimicrobial agents for food packaging applications. Trends in Food Science & Technology, 33(2), 110–123.Theinsathid, P., Visessanguan, W., Kruenate, J., Kingcha, Y., & Keeratipibul, S. (2012). Antimicrobial activity of lauric arginate-coated polylactic acid films against Listeria monocytogenes and Salmonella typhimurium on cooked sliced ham. Journal of Food Science, 77(2), M142–149
Reversible Covalent Immobilization of Cinnamaldehyde on Chitosan Films via Schiff Base Formation and Their Application in Active Food Packaging
[EN] In this work, cinnamaldehyde was reversibly anchored to chitosan films via imino-covalent bonding. The Schiff base was synthesized in solid phase employing neutralized chitosan films immersed in acidified 95 % (v/v) ethanolic solution in which the aldehyde was dissolved. The substitution degree (%) of cinnamaldehyde to the amine group was close to 70 %. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analysis revealed the formation of the chitosan-cinnamaldehyde Schiff base. The hydrolysis of the imino bond and subsequent release of cinnamaldehyde were studied after the films had been subjected to different combinations of temperature/time treatments simulating food preservation methods. The amount of aldehyde that remained covalently attached to the films was monitored by ATR-FTIR, and the substitution degree was determined by elemental analysis. Surface contact angle and colour parameters of cinnamaldehyde-imine-chitosan films and these films subjected to different treatments were also evaluated. The antimicrobial properties of chitosan-Schiff base films were tested in vitro against Staphylococcus aureus and Escherichia coli and in milk inoculated with Listeria monocytogenes. The antimicrobial activity varied depending on the treatment applied and consequently the degree of imino bond hydrolysis achieved and cinnamaldehyde released. Films of Schiff base-chitosan derivative subjected to different time/temperature treatments inhibited the growth of L. monocytogenes for 12 days under refrigeration conditions, which may extend the microbiological shelf life of such products. Sensory analysis of milk in contact with the films showed that a cinnamon smell does not cause any rejection among potential consumers. These novel films could be used in the design of antimicrobial food packaging and in various other technological areas where sustained-release systems are requiredThe authors wish to thank the financial support provided by the Spanish Ministry of Science and Innovation (project AGL2012-39920-C03-01) and Spanish Research Council (CSIC, JAE-Predoc L.H. fellowship).Higueras-Contreras, L.; Lopez-Carballo, G.; Gavara Clemente, R.; Hernández-Muñoz, P. (2015). Reversible Covalent Immobilization of Cinnamaldehyde on Chitosan Films via Schiff Base Formation and Their Application in Active Food Packaging. Food and Bioprocess Technology. 8(3):526-538. https://doi.org/10.1007/s11947-014-1421-8S52653883Abreu, F. O., Oliveira, E. F., Paula, H. C., & de Paula, R. (2012). Chitosan/cashew gum nanogels for essential oil encapsulation. Carbohydrate Polymers, 89(4), 1277–1282.Balaguer, M. P., Gómez-Estaca, J., Gavara, R., & Hernández-Muñoz, P. (2011a). Biochemical properties of bioplastics made from wheat gliadins cross-linked with cinnamaldehyde. Journal of Agricultural and Food Chemistry, 59(24), 13212–13220.Balaguer, M. P., Gómez-Estaca, J., Gavara, R., & Hernández-Muñoz, P. (2011b). Functional properties of bioplastics made from wheat gliadins modified with cinnamaldehyde. Journal of Agricultural and Food Chemistry, 59(12), 6689–6695.Belletti, N., Lanciotti, R., Patrignani, F., & Gardini, F. (2008). Antimicrobial efficacy of citron essential oil on spoilage and pathogenic microorganisms in fruit-based salads. Journal of Food Science, 73(7), M331–M338.Burt, S. (2004). Essential oils: their antibacterial properties and potential applications in foods—a review. International Journal of Food Microbiology, 94(3), 223–253.Cocchiara, J., Lalko, J., Lapczynski, A., Letizia, C. S., & Api, A. M. (2005). Fragrance material review on cinnamaldehyde. Food and Chemical Toxicology, 43(6), 867–923.Coma, V., Martial-Gros, A., Garreau, S., Copinet, A., Salin, F., & Deschamps, A. (2002). Edible antimicrobial films based on chitosan matrix. Journal of Food Science, 67(3), 1162–1169.Damodaran, S., & Kinsella, J. E. (1980). Flavor protein interactions. Binding of carbonyls to bovine serum-albumin: thermodynamic and conformational effects. Journal of Agricultural and Food Chemistry, 28(3), 567–571.dos Santos, J. E., Dockal, E. R., & Cavalheiro, E. T. G. (2005). Synthesis and characterization of Schiff bases from chitosan and salicylaldehyde derivatives. Carbohydrate Polymers, 60(3), 277–282.Doyle, M. P., & Beuchat, L. R. (2007). Food microbiology: fundamentals and frontiers. Washington: ASM Press.Fleming, D. W., Cochi, S. L., MacDonald, K. L., Brondum, J., Hayes, P. S., Plikaytis, B. D., Holmes, M. B., Audurier, A., Broome, C. V., & Reingold, A. L. (1985). Pasteurized milk as a vehicle of infection in an outbreak of listeriosis. New England Journal of Medicine, 312(7), 404–407.Foster, L. J. R., & Butt, J. (2011). Chitosan films are not antimicrobial. Biotechnology Letters, 33(2), 417–421.Gallstedt, M., & Hedenqvist, M. S. (2006). Packaging-related mechanical and barrier properties of pulp-fiber-chitosan sheets. Carbohydrate Polymers, 63(1), 46–53.Gill, A., & Holley, R. (2004). Mechanisms of bactericidal action of cinnamaldehyde against Listeria monocytogenes and of eugenol against L. monocytogenes and Lactobacillus sakei. Applied and Environmental Microbiology, 70(10), 5750–5755.Guinesi, L. S., & Cavalheiro, E. T. G. (2006). Influence of some reactional parameters on the substitution degree of biopolymeric Schiff bases prepared from chitosan and salicylaldehyde. Carbohydrate Polymers, 65(4), 557–561.Guo, Z. Y., Xing, R. E., Liu, S., Zhong, Z. M., Ji, X., Wang, L., & Li, P. C. (2007). Antifungal properties of Schiff bases of chitosan, N-substituted chitosan and quaternized chitosan. Carbohydrate Research, 342(10), 1329–1332.Gutierrez, J., Barry-Ryan, C., & Bourke, R. (2008). The antimicrobial efficacy of plant essential oil combinations and interactions with food ingredients. International Journal of Food Microbiology, 124(1), 91–97.Higueras, L., López-Carballo, G., Cerisuelo, J. P., Gavara, R., & Hernández-Muñoz, P. (2013). Preparation and characterization of chitosan/HP-beta-cyclodextrins composites with high sorption capacity for carvacrol. Carbohydrate Polymers, 97(2), 262–268.Holley, R. A., & Patel, D. (2005). Improvement in shelf-life and safety of perishable foods by plant essential oils and smoke antimicrobials. Food Microbiology, 22(4), 273–292.Hosseini, S., Zandi, M., Rezaei, M., & Farahmandghavi, F. (2013). Two-step method for encapsulation of oregano essential oil in chitosan nanoparticles: preparation, characterization and in vitro release study. Carbohydrate Polymers, 95(1), 50–56.Huang, Z.H., Wan, D.C. & Huang, J.L. (2001). Hydrolysis of Schiff bases promoted by UV light. Chemistry Letters, (7), 708–709.Inukai, Y., Chinen, T., Matsuda, T., Kaida, Y., & Yasuda, S. J. (1998). Selective separation of germanium (IV) by 2,3-dihydroxypropylchitosan resin. Analytica Chimica Acta, 371(2–3), 187–193.Ji, C., & Shi, J. (2013). Thermal-crosslinked porous chitosan scaffolds for soft tissue engineering applications. Materials Science and Engineering: C, 33(7), 3780–3785.Jin, X., Wang, J., & Bai, J. (2009). Synthesis and antimicrobial activity of the Schiff base from chitosan and citral. Carbohydrate Research, 344(6), 825–829.Junttila, J. R., Niemela, S. I., & Hirn, J. (1988). Minimum growth temperatures of Listeria monocytogenes and non-haemolytic Listeria. Journal of Applied Bacteriology, 65(4), 321–327.Kasaai, M. R., Arul, J., Chin, S. L., & Charlet, G. (1999). The use of intense femtosecond laser pulses for the fragmentation of chitosan. Journal of Photochemistry and Photobiology, A: Chemistry, 120(3), 201–205.Kirdant, A. S., Shelke, V. A., Shankarwar, S. G., Shankarwar, A. G., & Chondhekar, T. K. (2011). Kinetic study of hydrolysis of N-salicylidene-m-methyl aniline spectrophotomerically. Journal of Chemical and Pharmaceutical Research, 3(4), 790–796.Kuhn, J., Considine, T., & Singh, H. (2006). Interactions of milk proteins and volatile flavor compounds: implications in the development of protein foods. Journal of Food Science, 71(5), R72–R82.Li, X., Shao, T., Shi, Q., & Hu, M. (2013). A diaryl Schiff base as a photo- and pH-responsive bifunctional molecule. RSC Advances, 3(45), 22877–22881.Lovett, J., Francis, D. W., & Hunt, J. M. (1987). Listeria monocytogenes in raw milk: detection, incidence, and pathogenicity. Journal of Food Protection, 50(3), 188–192.Mohamad, A. (2013). Reactivity of base catalysed hydrolysis of 2-pyridinylmethylene-8-quinolinyl-Schiff base iron(II) iodide complexes: solvent effects. Chemické zvesti, 67(4), 464–476.Muhamad, S. G. (2011). First photolysis of benzidine Schiff base in non aqueous solvents. International Journal of Chemistry, 1(3), 142–145.Muriel-Galet, V., López-Carballo, G., Gavara, R., & Hernández-Muñoz, P. (2012). Antimicrobial food packaging film based on the release of LAE from EVOH. International Journal of Food Microbiology, 157(2), 239–244.Nazzaro, F., Fratianni, F., De Martino, L., Coppola, R., & De Feo, V. (2013). Effect of essential oils on pathogenic bacteria. Pharmaceuticals, 6(12), 1451–1474.Renault, F., Sancey, B., & Crini, G. (2009). Chitosan for coagulation/flocculation processes—an eco-friendly approach. European Polymer Journal, 45(5), 1337–1348.Sashiwa, H., & Aiba, S. I. (2004). Chemically modified chitin and chitosan as biomaterials. Progress in Polymer Science, 29(9), 887–908.Shahidi, F., Arachchi, J. K. V., & Jeon, Y. J. (1999). Food applications of chitin and chitosans. Trends in Food Science & Technology, 10(2), 37–51.Vallapa, N., Wiarachai, O., Thongchul, N., Pan, J. S., Tangpasuthadol, V., Kiatkamjornwong, S., & Hoven, V. P. (2011). Enhancing antibacterial activity of chitosan surface by heterogeneous quaternization. Carbohydrate Polymers, 83(2), 868–875.Wang, J. T., Lian, Z. R., Wang, H. D., Jin, X. X., & Liu, Y. J. (2012). Synthesis and antimicrobial activity of Schiff base of chitosan and acylated chitosan. Journal of Applied Polymer Science, 123(6), 3242–3247.Zivanovic, S., Chi, S., & Draughon, A. F. (2005). Antimicrobial activity of chitosan films enriched with essential oils. Journal of Food Science, 70(1), M45–M51
Novel antimicrobial zein film for controlled release of lauroyl arginate (LAE)
Novel antimicrobial biopolymer films based on the incorporation of ethyl-Nα-dodecanoyl-l-arginate hydrochloride (LAE) in zein matrices were manufactured and characterized as materials for LAE controlled released applications such as active food packaging. Characterization of the films’ functional properties revealed that incorporation of LAE (5 and 10%) in the biopolymer matrix did not cause substantial changes in morphological, optical, thermal, mechanical and barrier properties.
As the mechanism of action of these films is mainly based on release of the antimicrobial, this process was characterized when the active biofilms were exposed to three food simulants (water, 3% acetic acid, and 10% alcohol) at three temperatures (4, 23, and 37 °C). The data obtained revealed that, with the exception of exposure to water at 4 °C which achieved a release of more than 80% of the LAE incorporated, the agent was almost completely extracted in all conditions. Release of LAE was faster at higher temperatures, and the diffusion coefficient values varied according to the Arrhenius law, and increased with temperature. Antibacterial activity of films was assayed against Listeria monocytogenes and Escherichia coli. Zein films with 5% LAE produced 2.02 and 3.07 log reduction against L. monocytogenes and E. coli, respectively, after 5 days of storage at 4 °C. Greater antibacterial activity was observed with films containing 10% LAE (5 log reduction) at 37 °C. This work highlighted that LAE incorporation in a packaging film constructed with renewable polymer materials offers an interesting and efficient hurdle for control of bacterial contamination in foods.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness, projects AGL2012-39920-C03-01. M.K. thanks the Ministry of Sciences, Research and Technology of Iran for her grant. I.D. thanks the CSIC for her postdoctoral contract (JAE-DOC).Peer reviewe
Immobilization of beta-cyclodextrin in ethylene-vinyl alcohol copolymer for active food packaging applications
[EN] Current developments in active food packaging are focusing on incorporating agents into the polymeric package walls that will release or retain substances to improve the quality, safety and shelf-life of the food. Because cyclodextrins are able to form inclusion complexes with various compounds, they are of potential interest as agents to retain or scavenge substances in active packaging applications. In this study, beta-cyclodextrin (beta CD) was successfully immobilized in an ethylene-vinyl alcohol copolymer with a 44% molar percentage of ethylene (EVOH44) by using regular extrusion with glycerol as an adjuvant. Films with 10%, 20% and 30% of beta CD were flexible and transparent. The presence of the agent slightly increased the glass-transition temperature and the crystallinity percentage of the polymer, that is to say, it induced some fragility and a nucleating effect. The water vapor, oxygen and carbon dioxide barrier properties of the materials containing beta CD were determined and compared with those of the pure polymeric material. Permeability to these three permeants increased with the addition of beta CD due to the presence of discontinuities in the matrix and to the internal cavity of the oligosaccharide. Also the CO2/O-2 permselectivity increased with the addition of beta CD. Finally, the potential effect of the composites in the food aroma was analyzed. The materials with beta CD preferentially sorbed apolar compounds such as terpenes. This characteristic could be useful in active packaging applications for preferentially retaining undesired apolar food components like hexanal or cholesterol. (C) 2010 Elsevier B.V. All rights reserved.The authors acknowledge the financial support of the Spanish Ministry of Science and Innovation, projects AGL2006-02176 and Fun-C-Food CSD2007-00063, and the C. L-d-D fellowship (FPU program). Mary Georgina Hardinge provided assistance with the English language text.Lopez-De-Dicastillo, C.; Gallur, M.; Catala Moragrega, R.; Gavara Clemente, R.; Hernandez-Muñoz, P. (2010). Immobilization of beta-cyclodextrin in ethylene-vinyl alcohol copolymer for active food packaging applications. Journal of Membrane Science. 353(1-2):184-191. https://doi.org/10.1016/j.memsci.2010.02.049S1841913531-
Innovations and trends in the packaging of fruits and vegetables
[SPA] Los cambios fÃsicos, quÃmicos y microbiológicos que tienen lugar en las frutas y hortalizas tras su recolección llevan indefectiblemente a la pérdida de calidad y aceptabilidad durante su comercialización. Con la elección de la tecnologÃa de conservación y envasado y del material de envase con las adecuadas caracterÃsticas de barrera a gases y vapores, asà como su respuesta a los diferentes factores externos como la temperatura, la humedad, la luz, y las manipulaciones propias de la comercialización se puede conseguir alargar la vida útil de los alimentos con garantÃas de calidad y seguridad. El envasado en atmósfera modificada es en la actualidad la tecnologÃa de conservación más ampliamente utilizada para la comercialización de frutas y hortalizas en fresco. Con la adecuada composición de la atmósfera de envasado en combinación con la refrigeración se reduce el crecimiento de microorganismos, asà como los procesos metabólicos y la pérdida de agua. Ahora bien, esta tecnologÃa de envasado no es suficiente en muchas ocasiones para mantener adecuadamente el producto durante todo el periodo de comercialización y hasta su consumo. El envasado activo puede significar para estos productos una excelente alternativa, efectiva y económica para la conservación de estos productos. En esta ponencia se revisan las bases del envasado activo y se comentan algunas de las tecnologÃas de interés práctico y las perspectivas de futuro. [ENG] The physical, chemical and microbiological changes that take place in fruits and vegetables after harvesting lead unfailingly to the loss of quality and acceptability during their commercialization. It is possible to lengthen the shelf life of food maintaining its quality and security with an adequate election of preservation and packaging technologies and a package design with the appropriate barrier characteristics to gases and vapours, as well as its responses to the different external factors such as temperature, humidity, light, and manipulations during de distribution and marketing, Among the diverse packaging alternatives, modified atmosphere packaging is the most common preservation technology for fresh produce since it can help to decrease respiration rate and transpiration, retard or prevent microbial growth and reduce metabolic activity in minimally processed fruits and vegetables. Although this packaging technology in combination with refrigeration can delay deterioration of the fresh product, it is not always sufficient for the purpose of maintaining its quality for the desired marketing period. As an alternative, active packaging opens up an effective, economical way of increasing the shelf life of fresh produce during transport and marketing. This presentation reviews the present state and future perspectives of both modified atmosphere packaging and active packaging technologies for fruits and vegetables
Modification of polyetherimide membranes with ZIFs fillers for CO2 separation
[EN] Flat hybrid membranes composed of polyetherimide (PEI) as matrix and zeolitic imidazolate frameworks (ZIFs) as fillers at concentrations of 10 and 20 wt% were prepared. Apparent permeability coefficient and apparent diffusivity coefficient of gases (CO2 and N-2) for these hybrid membranes (PZIFs) were determined by the "timelag" method. The experimental conditions used were from 25 degrees C to 55 degrees C with pressures of 2, 3 and 5 bar. The PZIFs with fillers of ZIF-8 (PZ-Zn) and ZIF-67 (PZ-Co) showed apparent selectivities (alpha(pa(CO2)/pa(N2))) of 39.6 and 27.5, respectively, higher than the alpha(pa(CO2)/pa(N2)) of the reference membrane PEI, while the membrane with filler of ZIF-Mix (PZ-Zn/Co) showed the lowest alpha(pa(CO2)()/pa(N2)) selectivity of 10.3 in the membrane series (under conditions of 25 degrees C and 2 bar). It is proposed that the selectivity of the membrane series can be attributed to two critical factors: the particle size/distribution ratio in the polymer base and sorption of CO2 at local sites of the bimetallic mixture.
On the other hand, gas permeation studies (O-2, CO2 and CH4, and CO2/CH(4 )and CO2/C2H4 mixtures), were carried out in the series of PZIFs membranes. Permeability data were obtained by an isostatic method based on a permeation cell connected in series to a gas chromatograph where the rate of permeated gases was analyzed until a stationary state was reached. The complementary characterization techniques were: scanning electron microscopy, thermogravimetric analysis, and powder X-ray diffraction, which support the existence of the amorphous/crystalline phases of the PZIFs.This research has been supported by the ENE/2015-69203-R project, granted by the Ministerio de Economia y Competitividad (MINECO), Spain; Also authors are grateful to UNAM-DGAPA-PAPIIT projects IG-100185, and IG-114818.
This study was partially supported by the CONACyT (Mexico) projects 2013-05-231461 and CB -2014-01-235840.Vega, J.; Andrio, A.; Lemus, A.; DÃaz, J.; Del Castillo, L.; Gavara, R.; Compañ Moreno, V. (2019). Modification of polyetherimide membranes with ZIFs fillers for CO2 separation. Separation and Purification Technology. 212:474-482. https://doi.org/10.1016/j.seppur.2018.11.033S47448221
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