Estudo da formação de microemulsões em misturas de surfactante/óleos vegetais e interação com vitaminas e sais
Data
2007-11-08
Autores
Polizelli, Marcos Alexandre [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Foram construídos diagramas de fases ternários e pseudo-ternários parciais a 25 °C dos sistemas: óleo de soja (OS)/Monooleína(MO):Bis (2-etilhexil) sulfosuccinato de sódio (AOT)/água (a), OS/La-fosfatidilcolina(FC):Bis (2-etilhexil) sulfosuccinato de sódio (AOT)/solução aquosa de NaCl (b), e óleo essencial de laranja (OEL)/AOT/água (c), a fim de identificar fases de microemulsões (ME) de água em óleo (W/O). Para o sistema (a) a área da fase de MEs no diagrama de fases depende da razão MO:AOT, sendo maior para a razão 2:1. Experimentos reológicos, de espalhamento dinâmico de luz (DLS) e de espalhamento de raios-X a baixo ângulo (SAXS) indicam a existência de uma ME de água em óleo (W/O) esférica (região L2), e estruturas lamelares locais (região L2’). Na ausência de NaCl os diagramas de fases do sistema (b) exibem uma fase de ME com áreas dependentes da razão FC:AOT; sendo a maior para a razão 1:1. A área da fase de MEs no diagrama aumenta com a concentração de NaCl até a saturação ao redor de 11% (m/m) de sal. Neste sistema também foram identificadas MEs esféricas e agregados “secos” não esféricos. Para o sistema (c) foram identificadas duas monofases, uma isotrópica de ME W/O (L2) e uma fase líquido-cristalina. A região de ME W/O (L2) também mostrou ser composta por dois tipos de agregados, esféricos e não esféricos, como indicado por experimentos de reologia, condutividade elétrica e SAXS. Aditivos alimentares (ácido ascórbico, ácido fólico, cloreto de sódio e sulfato ferroso) foram incorporados nas MEs (a e b). As viscosidades dessas MEs enriquecidas aproximam-se do óleo de soja puro. As MEs também mostraram ter estabilidade oxidativa, em alguns casos próxima e em outros até oito vezes superior à do óleo de soja puro, exceto para MEs enriquecidas com ferro. Tais resultados indicam...
Partial ternary and pseudoternary phase diagrams at 25 °C were built for the systems soy bean oil (SOB)/monoolein (MO)/sodium bis-2-(ethylhexyl)sulfosuccinate (AOT)/water (a), soy bean oil/La-phosphatidylcholine (PC)/sodium bis-2- (ethylhexyl)sulfosuccinate (AOT)/aqueous NaCl solution (b), and orange essential oil (OEO)/sodium bis-2-(ethylhexyl)sulfosuccinate (AOT)/water (c), and the phases consisting of water-in-oil (W/O) microemulsion (ME) were identified. For system (a) the area of the ME phase depends on the MO:AOT ratio, being larger for ratio 2:1. Rheology, dynamic light scattering and small angle X ray scattering (SAXS) measurements indicate the existence of water-in-oil (W/O) spherical MEs (L2 region), and a local lamellar structure (region L2´). In absence of NaCl the phase diagram for system (b) exhibits an isotropic phase of ME that depends on the PC:AOT ratio; being larger for ratio 1:1. Furthermore, the phase area for MEs in the diagram increases with NaCl concentration up to saturation at around 11 wt% salt. In this system it was also identified spherical MEs and non spherical dry” aggregates. For system (c) two single phases were identified, a W/O ME isotropic (L2) and a liquid crystalline phase, and a two-phase region. The ME region (L2) also showed be formed by spherical and non spherical aggregates, as suggested by rheological, electric conductivity and SAXS experiments. Food grade additives (ascorbic acid, folic acid or ferrous sulfate) were incorporated into ME droplets in system (a and b). The viscosity of such ME approaches that of pure SBO. Moreover, these ME present oxidative stability up to eight-fold the pure SBO. Exception is for ME enriched with iron. Such results indicate that ME enriched with nutrients present a high potential for application. It can also be concluded that the MEs with ascorbic acid can act as antioxidant for SBO.
Partial ternary and pseudoternary phase diagrams at 25 °C were built for the systems soy bean oil (SOB)/monoolein (MO)/sodium bis-2-(ethylhexyl)sulfosuccinate (AOT)/water (a), soy bean oil/La-phosphatidylcholine (PC)/sodium bis-2- (ethylhexyl)sulfosuccinate (AOT)/aqueous NaCl solution (b), and orange essential oil (OEO)/sodium bis-2-(ethylhexyl)sulfosuccinate (AOT)/water (c), and the phases consisting of water-in-oil (W/O) microemulsion (ME) were identified. For system (a) the area of the ME phase depends on the MO:AOT ratio, being larger for ratio 2:1. Rheology, dynamic light scattering and small angle X ray scattering (SAXS) measurements indicate the existence of water-in-oil (W/O) spherical MEs (L2 region), and a local lamellar structure (region L2´). In absence of NaCl the phase diagram for system (b) exhibits an isotropic phase of ME that depends on the PC:AOT ratio; being larger for ratio 1:1. Furthermore, the phase area for MEs in the diagram increases with NaCl concentration up to saturation at around 11 wt% salt. In this system it was also identified spherical MEs and non spherical dry” aggregates. For system (c) two single phases were identified, a W/O ME isotropic (L2) and a liquid crystalline phase, and a two-phase region. The ME region (L2) also showed be formed by spherical and non spherical aggregates, as suggested by rheological, electric conductivity and SAXS experiments. Food grade additives (ascorbic acid, folic acid or ferrous sulfate) were incorporated into ME droplets in system (a and b). The viscosity of such ME approaches that of pure SBO. Moreover, these ME present oxidative stability up to eight-fold the pure SBO. Exception is for ME enriched with iron. Such results indicate that ME enriched with nutrients present a high potential for application. It can also be concluded that the MEs with ascorbic acid can act as antioxidant for SBO.
Descrição
Palavras-chave
Físico-química, Quimica de superficie, Coloides, Microemulsões, Tensoativos
Como citar
POLIZELLI, Marcos Alexandre. Estudo da formação de microemulsões em misturas de surfactante/óleos vegetais e interação com vitaminas e sais. 2007. 98 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2007.