Caracterización de emulsiones y oleogeles con hidroxipropilmetilcelulosa y micropartículas de quitina.
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Date
2025
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Universidad de Concepción
Abstract
El elevado consumo de grasas es uno de los factores de riesgo asociado a diversas enfermedades. Una de las soluciones planteadas es la estructuración de aceites, denominados oleogeles. El objetivo de este trabajo fue el estudio de las propiedades fisicoquímicas de emulsiones y oleogeles elaborados con aceite de girasol, empleando diferentes concentraciones y pesos moleculares de HPMC, así como la incorporación de micropartículas de quitina utilizando el método emulsión template.
Se evaluaron las siguientes variables: concentración de HPMC en emulsión (1,5; 2,0 y 2,5% p/p), tipo de HPMC (alto o bajo peso molecular) y concentración de quitina en emulsión (0,5; 1,0 y 1,5% p/p) para una concentración fija de HPMC (1,5% p/p y bajo peso molecular). Los oleogeles se obtuvieron mediante el método de emulsion template. Las emulsiones se secaron por convección a 80°C, empleando relaciones aceite/agua de 50:50. La caracterización incluyó ensayos reológicos, microscopía, análisis de perfil de textura (TPA), colorimetría y evaluación de la retención de aceite (OBC). Para las emulsiones se realizaron barridos de deformación (0,01-100%), frecuencia (0,1-10 Hz), curvas de flujo (0,01-1 s⁻¹) y análisis del tamaño de gota mediante microscopía. Por su parte, los oleogeles se les aplicaron barridos de deformación (0,01-10%), frecuencia (0,1-10 Hz), rampas térmicas (25-80°C), TPA, colorimetría y OBC.
El aumento de HPMC incrementó los módulos viscoelásticos y redujo el tamaño de gota de las emulsiones. Las emulsiones con HPMC de alto peso molecular (HPMC A) mostraron un punto de gel que se ajustó bien al modelo generalizado de Maxwell con cuatro elementos. Los modelos de Cross-Williamson y Casson describieron adecuadamente el comportamiento viscoso de las emulsiones. La incorporación de micropartículas de quitina aumentó la viscosidad del medio, pero no afectaron significativamente el comportamiento viscoelástico ni la distribución del tamaño de gota producto del tamaño de partícula (20-100 μm) similar a las gotas de aceite.
En los oleogeles, el aumento de la concentración de HPMC de bajo peso molecular (HPMC B) conllevó a una mayor estructuración de los sistemas, dureza y OBC. Para HPMC A, estas propiedades permanecieron constantes. La incorporación de quitina en los oleogeles con HPMC B conllevó a un aumento de los módulos viscoelásticos, dureza y croma, pero una disminución desfavorable del OBC. Todos los oleogeles presentaron alta termoestabilidad y no se observaron cambios significativos en los parámetros de color con el aumento de HPMC independiente del tipo.
Excessive dietary fat intake is recognized as a risk factor for several health disorders. Structuring oils, known as oleogels, is one proposed solution. The aim of this study was to examine the physicochemical properties of sunflower oil emulsions and oleogels prepared with different concentrations and molecular weights of HPMC, and to evaluate the effect of incorporating chitin microparticles using the emulsion-template method. The study evaluated the following variables: HPMC concentration in the emulsion (1.5, 2.0, and 2.5% w/w), HPMC type (high- or low- molecular weight), and chitin concentration in the emulsion (0.5, 1.0, and 1.5% w/w) evaluated at a fixed HPMC concentration (1,5% w/w and low-molecular weight). Oleogels were produced using the emulsion-template method. Oil-in-water emulsions (50:50) were convectively dried at 80°C. Characterization included rheological measurements, optical microscopy, texture profile analysis (TPA), colorimetry, and oil binding capacity (OBC). For the emulsions, strain sweeps (0.01–100%), frequency sweeps (0.1–10 Hz), flow curves (0.01–1 s⁻¹), and droplet size distribution analyses were conducted. For the oleogels, strain sweeps (0.01–10%), frequency sweeps (0.1–10 Hz), thermal ramps (25–80°C), TPA, colorimetry, and OBC determinations were performed. An increase in HPMC concentration enhanced the viscoelastic moduli and reduced the droplet size of the emulsions. Emulsions with high–molecular weight HPMC (HPMC A) exhibited a gel point that was satisfactorily fitted by the four-element generalized Maxwell model. The Cross-Williamson and Casson models adequately described the viscous behaviour of the emulsions. The incorporation of chitin microparticles increased the viscosity of the medium but did not significantly affect the viscoelastic behavior or droplet size distribution, because the particle size (20–100 μm) was comparable to that of the oil droplets. In the oleogels, increasing the concentration of low–molecular weight HPMC (HPMC B) led to greater structuring of the systems, higher hardness, and increased OBC. For HPMC A, these properties remained constant. The incorporation of chitin into oleogels with HPMC B resulted in increased viscoelastic moduli, hardness, and chroma, but caused an unfavorable decrease in OBC. All oleogels exhibited high thermal stability, and no significant changes in color parameters were observed with increasing HPMC, regardless of type.
Excessive dietary fat intake is recognized as a risk factor for several health disorders. Structuring oils, known as oleogels, is one proposed solution. The aim of this study was to examine the physicochemical properties of sunflower oil emulsions and oleogels prepared with different concentrations and molecular weights of HPMC, and to evaluate the effect of incorporating chitin microparticles using the emulsion-template method. The study evaluated the following variables: HPMC concentration in the emulsion (1.5, 2.0, and 2.5% w/w), HPMC type (high- or low- molecular weight), and chitin concentration in the emulsion (0.5, 1.0, and 1.5% w/w) evaluated at a fixed HPMC concentration (1,5% w/w and low-molecular weight). Oleogels were produced using the emulsion-template method. Oil-in-water emulsions (50:50) were convectively dried at 80°C. Characterization included rheological measurements, optical microscopy, texture profile analysis (TPA), colorimetry, and oil binding capacity (OBC). For the emulsions, strain sweeps (0.01–100%), frequency sweeps (0.1–10 Hz), flow curves (0.01–1 s⁻¹), and droplet size distribution analyses were conducted. For the oleogels, strain sweeps (0.01–10%), frequency sweeps (0.1–10 Hz), thermal ramps (25–80°C), TPA, colorimetry, and OBC determinations were performed. An increase in HPMC concentration enhanced the viscoelastic moduli and reduced the droplet size of the emulsions. Emulsions with high–molecular weight HPMC (HPMC A) exhibited a gel point that was satisfactorily fitted by the four-element generalized Maxwell model. The Cross-Williamson and Casson models adequately described the viscous behaviour of the emulsions. The incorporation of chitin microparticles increased the viscosity of the medium but did not significantly affect the viscoelastic behavior or droplet size distribution, because the particle size (20–100 μm) was comparable to that of the oil droplets. In the oleogels, increasing the concentration of low–molecular weight HPMC (HPMC B) led to greater structuring of the systems, higher hardness, and increased OBC. For HPMC A, these properties remained constant. The incorporation of chitin into oleogels with HPMC B resulted in increased viscoelastic moduli, hardness, and chroma, but caused an unfavorable decrease in OBC. All oleogels exhibited high thermal stability, and no significant changes in color parameters were observed with increasing HPMC, regardless of type.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Químico/a.
Keywords
Emulsiones, Aceites vegetales, Quitina