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RESUMENEstudios sobre la extracción de aceite de germen de trigo mediante hexano comercial.

RESUMENExtracción con disolventes del aceite de jojoba a partir de harina prensada de jojoba.Se ha estudiado el proceso de extracción con disolventes del aceite contenido en la harina residual del prensado mecánico de las semillas de jojoba. Como disolventes se han utilizado hexano técni-co y éter de petróleo, habiéndose efectuado extracciones a temperaturas comprendidas entre 30 o y 55 o C, con relaciones de disolvente a sólido, R, de entre 12 y 15 L/kg. Se han determinado las composiciones del extracto y del residuo sólido en el equilibrio y a partir de los datos de equilibrio, se ha estimado el coeficiente de partición o cociente de distribución, D, del aceite entre ambas fases. Asimismo, se ha determinado el número de etapas de extracción necesarias para conseguir un cierto grado de recuperación del aceite, utilizando diferentes relaciones entre hexano y harina.También se han determinado las propiedades físicas y quími-cas del aceite de jojoba, incluyendo la composición química, el porcentaje de ácidos grasos, el índice de peróxidos, el punto de inflamación, el punto de ignición, el punto de deslizamiento, el ín-dice de refracción y los índices de saponificación y de yodo. Se ha estudiado asimismo la estabilidad del aceite durante su almacenamiento a temperatura ambiente y durante el calentamiento. PALABRAS-CLAVE: Aceite de jojoba -Extracción con disolventes -Lixiviación. Semilla de jojoba. SUMMARY Solvent extraction of jojoba oil from pre-pressed jojoba meal.The solvent extraction process of jojoba oil from the meal cake obtained after the mechanical pressing of jojoba seeds was studied. Commercial hexane and petroleum ether were used as solvents and the extraction was carried out at temperatures ranging from 30 to 55 o C using solvent-to-solid ratios, R, between 2 and 15 L/kg. The equilibrium compositions of the solvent and solid phases were determined. Based on the equilibrium data, the partition coefficient or distribution ratio, D, of the oil between both phases was estimated. Also, the number of extraction stages necessary to achieve a certain degree of oil recovery has been determined using different hexane-to-meal ratios.Jojoba oil was also tested for its physical and chemical properties including chemical composition, percentage fatty acid, peroxide value, flash point, fire point, pour point, refractive index, saponification and iodine values. The stability of jojoba oil during storage at room temperature and during heat treatment was also studied.

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Formation of a low-fat oil-in-water (O/W) nanoemulsion enriched with vitamin E using the nonionic surfactant Tween 40 is studied by means of a high-pressure homogenizer. The effect of different process variables of the emulsification process, including pressure, temperature, and concentration of the emulsifying agent, is evaluated. The relation between pressure and the obtained mean droplet diameter is derived and described by an equation which can be taken as a basis of any process design. The droplet size can be decreased by increasing the vitamin E concentration. A higher fat content slightly affects the droplet size distribution and the mean droplet diameter of the nanoemulsion, so it is recommended to use preparations of nanoemulsions with low fat contents enriched with vitamin E for dietary supplement.