Evaluación de propiedades mecánicas, ópticas, antioxidantes y de barrera de películas comestibles elaboradas con emulsiones dobles W₁/O/W₂ adicionadas con extracto de té verde (Camellia sinensis)
The edible films can extend life and improve food quality by acting as a mechanical protection and a selective barrier to the transmission of gases, fumes, smells, tastes and solutes. Act as a support for carrying active substances such as antibiotics, probiotics, antioxidants, and others. It has be...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2011 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:8p58pd20p |
| Acceso en línea: | https://doi.org/10.24275/uami.8p58pd20p |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Reología info:eu-repo/classification/LEM/Películas delgadas info:eu-repo/classification/LEM/Proteins -- Biotechnology info:eu-repo/classification/LEM/Thin films info:eu-repo/classification/LEM/Emulsiones info:eu-repo/classification/LEM/Industria alimentaria info:eu-repo/classification/LEM/Revestimientos info:eu-repo/classification/LEM/Emulsions info:eu-repo/classification/LEM/Rheology info:eu-repo/classification/LEM/Proteínas -- Biotecnología info:eu-repo/classification/LEM/Coatings info:eu-repo/classification/cti/6 |
| Sumario: | The edible films can extend life and improve food quality by acting as a mechanical protection and a selective barrier to the transmission of gases, fumes, smells, tastes and solutes. Act as a support for carrying active substances such as antibiotics, probiotics, antioxidants, and others. It has been suggested the incorporation of lipid materials to increase hydrophobicity and improve the water vapor permeability of films. The composite films usually consist of proteins, polysaccharides (or a mixture of both) and a lipid bilayer, or multilayer emulsion. Emulsified films have similar properties to the bilayer ones but with the advantage that its preparation is done in one step. The aim of this study was: (a) obtain W1/O/W2 double emulsions by two different protein-polysaccharide complex (isolated whey protein (WPI)-low methoxyl pectin (LMP) and WPI- carboxymethyl cellulose (CMC)) and evaluate their rheological properties (fixed and dynamic), measure the volume of the droplet surface, (b) obtain edible films by pouring the double emulsion in a plate and (c) to study the effect of time storage and the addition of water soluble green tea extract on the properties of the films. Emulsions stabilized by WPI-LMP-complex (ELMP-WPI) and CMC-WPI (ECMC-WPI) were used for the preparation of films which showed a particle size of 2.47μm and 10.68μm respectively. The particle size of double emulsions increased with the addition of green tea extract to be from 7.15 microns to ELMP-WPI-GT and 14.10 microns for ECMC-WP-GT. The viscosity in emulsions ELMP-WPI and ECMC-WPI exhibited flow curves for typical structural materials that are characterized by a Newtonian viscosity at low shear rates, a shear-thinning region in a range of higher shear rate. This kind of viscosity is characteristic of many non-Newtonian fluid, data were fitted well to the modified Carreau model (R2> 0.979). The double emulsion ELMP-WPI showed greater loss modulus (G'') than storage modulus (G ') in the frequency range studied. In addition, ECMC-WPI emulsion exhibited higher values of G' and G'' throughout the entire frequency range. Both modules showed a significant dependence on frequency which increased when this parameter was increased too. This behavior may be due to the difference in droplet size of double emulsions. While the general behavior was more liquid than solid, within a frequency range in which G 'and G'' are superimposed, showing that this behavior is related more to a network embedded in a soft matrix and stiffness in those regions can be produced by chemical or physical cross-linking. LMP-WPI films (PLMP-WPI) or CMC-WPI (PCMC-WPI) were dried at 25 ° C. The microstructure of PLMP- WPI and PCMC-WPI films are, in general, compact structures interrupted by small droplets of emulsion. The films that showed a more open microstructure were PCMC-WPI films that had a larger drop size. The mechanical properties were higher for PLMP-WPI films with a tensile strength of 1.49 MPa and a Young's modulus of 119.74 MPa. The values of water vapor permeability (WVP) of films were not significantly different between PLMP-WPI and P CMC-WPI valued 1.6-1.5 gmm/m2 h kPa, respectively. The films formed with emulsions with added green tea (PLMP-WPI-GT and PCMC-WPI-GT) favored the properties of the films because they showed greater RT and MY than PLMP-WPI and PCMC-WPI. On the other hand, the storage time significantly decreased the mechanical properties of films made with double emulsions, apparently during the storage period of 15 days followed by a dehydration of the films and / or crystallization of plasticizers and surfactants, causing change in mechanical properties, decreasing the flexibility of the film matrix and increasing the water vapor permeability. Films with and without green tea extract showed lower percentages of transparency, but PCMC-WPI films were less transparent with a transparency percentage of 6.81%. Color index (CI) of the PCMC-WPI and PLMP-WPI was within the range of color from dark green to yellowish green, while the color index of the films with green tea extract was found in the CI interval yellowish green. PCMC-WPI and PLMP-WPI films showed no phenolic compounds and antioxidant properties. The highest value of total phenols in edible films was after having been formed (at t = 0), significantly higher phenolic content in the films PLMP-WPI-GT (8.10 mg GA / g of film) that in PCMC-WPI-GT (7.85 mg GA / g of film). The antioxidant properties and the amount of total phenolic compounds of PLMP-WPI-GT were always higher, and the particle size of these emulsions was lower than that of PCMC-WPI-GT which could indicate that the particle size of double emulsions that form the matrix of the film plays an important role in protecting and probably in the release of green tea’s phenolic compounds. |
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