γ-Oryzanol and tocopherol contents in residues of rice bran oil refining.

Rice bran oil (RBO) contains significant amounts of the natural antioxidants γ-oryzanol and tocopherols, which are lost to a large degree during oil refining. This results in a number of industrial residues with high contents of these phytochemicals. With the aim of supporting the development of profitable industrial procedures for γ-oryzanol and tocopherol recovery, the contents of these phytochemicals in all the residues produced during RBO refining were evaluated. The samples included residues from the degumming, soap precipitation, bleaching earth filtering, dewaxing and deodorisation distillation steps. The highest phytochemical concentrations were found in the precipitated soap for γ-oryzanol (14.2 mg g(-1), representing 95.3% of total γ-oryzanol in crude RBO), and in the deodorisation distillate for tocopherols (576 mg 100 g(-1), representing 6.7% of total tocopherols in crude RBO). Therefore, among the residues of RBO processing, the deodorisation distillate was the best source of tocopherols. As the soap is further processed for the recovery of fatty acids, samples taken from every step of this secondary process, including hydrosoluble fraction, hydrolysed soap, distillation residue and purified fatty acid fraction, were also analyzed. The distillation residue left after fatty acid recovery from soap was found to be the best source of γ-oryzanol (43.1 mg g(-1), representing 11.5% of total γ-oryzanol in crude RBO).

Role of the co-surfactant nature in soybean w/o microemulsions.

The influence of the co-surfactant on physicochemical properties of w/o soybean oil microemulsions (MEs) has been studied. In spite of the similarity in phase diagrams, the MEs display remarkable differences when examined by electrical conductivity, dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and linear voltammetry. When different short-chain alcohols were employed as co-surfactants, together with sodium dodecyl sulfate (SDS) as surfactant, the DLS results indicated the systems to be monodisperse. Both the electrical conductivity of the MEs and the hydrodynamic radii of the droplets (R(H)) increased with water content while R(H) diminished as temperature increased, no aggregation or percolation of the droplets being observed. In comparison to w/o MEs prepared with 3-methyl-1-butanol, those prepared with 1-pentanol presented higher electrical conductivity and larger limiting currents at a Pt ultramicroelectrode for oxidation of the water occluded into the particles. Finally, from the electrochemical viewpoint the use of 1-pentanol is recommended, no advantage being gained by using any of the other tested alcohols.

Farelo de arroz: características, benefícios à saúde a aplicações / Rice bran: characteristics, health benefits and applications

Neste trabalho de revisão de literatura, a composição, a estabilidade, as aplicações e os benefícios à saúde do farelo de arroz foram abordados. Aspectos referentes à composição de biofenóis no óleo de arroz e novas tecnologias empregadas para extração e refino do óleo também foram discutidos. Subproduto do beneficiamento do arroz com amplas possibilidades de uso, o farelo evidencia grande potencial econômico. O consumo humano de farelo e óleo de arroz no Brasil ainda é reduzido, no entanto, a tendência do mercado mundial e as pesquisas apontam para promissoreas aplicações desse produto.

Characterization of hydroxyaromatic compounds in vegetable oils by capillary electrophoresis with direct injection in an oil-miscible KOH/propanol/methanol medium.

The separation of hydroxyaromatic compounds in vegetable oils, including synthetic antioxidants (3-tert-butyl-4-hydroxyanisol and 2,6-di-tert-butyl-4-hydroxytoluene), E-vitamers and other natural oil components, by nonaqueous capillary electrophoresis in an oil-miscible background electrolyte (BGE) was investigated. The BGE contained 40 mM KOH in a methanol/1-propanol (PrOH) mixture (15:85 v/v). The oil samples were 1:1 diluted with PrOH and directly injected in the capillary. Under negative polarity (cathode at the injection end), the anionic solutes moved faster than the electroosmotic flow, being well-resolved among them and from the triacylglycerols. Using virgin palm, extra virgin olive, wheat germ, virgin soybean and other oils, the capability of the procedure to quickly yield a characteristic profile of the biophenols present in the sample was demonstrated. The alpha-, (beta + gamma)- (as unresolved pair) and delta-tocopherols of a soybean oil sample were quantified.

Electrokinetic capillary chromatography in a polar continuous-phase water-in-oil microemulsion constituted by water, sodium dodecyl sulfate, and n-pentanol.

A water-in-oil (w/o) microemulsion (ME) constituted by 15% Tris buffer, pH 8.4, in water and 85% sodium dodecyl sulfate (SDS)/n-pentanol 1:4 mixture, capable of dissolving up to 30% vegetable oils and lard, was used as background electrolyte in reverse microemulsion electrokinetic capillary chromatography (RMEEKC). Owing to the free SDS ions in the continuous phase and some degree of percolation, the ME showed a high conductivity (0.65 mS. cm(-1) at 25 degrees C) and sustained a very stable capillary current. Previous rinsing of the capillary with a quaternary ammonium salt for electroosmotic flow (EOF) reduction, a series of nonionic and anionic solutes dissolved either in the ME or in fat samples diluted with the ME (1:4 ratio), were injected. Using -20 kV, fair separations of the solutes in the migration time order singly charged anions < nonionic solutes < doubly charged anions approximately pyromellitate were obtained, salicylate (I) showing by far the shortest migration time, and phthalate (II) and pyromellitate the longest. Separation was attributed to partition between the aqueous droplets, where pyromellitate and II were assumed to be trapped, and the n-pentanol continuous phase, where the mobilitites could be also modified by association of the solutes with SDS ions. Adequate EOF markers were not found, thus the relative mobility of any solute with respect to the mobility of the droplets, mu(r), was expressed as a fraction of the mobility of I with respect to that of the droplets, being mu(r) = (t(II) - t(R)) t(I) / [(t(II) - t(I)) t(R)], where t(R), t(I), and t(II) are the migration times of the solutes I and II, respectively. The application of RMEEKC to the analysis of both hydrophilic and hydrophobic samples, including edible fats, was demonstrated.