stearates and tristearin

This work aims at evaluating the influence of oil and gelator structure on organogels' properties through rheological measurements, polarized microscopy and small-angle X-ray scattering (SAXS). Four different food-grade gelators (glyceryl tristearate - GT; sorbitan tristearate - ST; sorbitan monostearate - SM and glyceryl monostearate - GM) were tested in medium-chain triglyceride and high oleic sunflower (MCT and LCT, respectively) oil phases. Organogels were prepared by mixing the oil phase and gelator at different concentrations (5, 10, 15, 20 and 25%) at 80°C during 30min. All organogels presented birefringence confirming the formation of a crystalline structure that changed with the increase of the gelator concentration. Through the evaluation of SAXS peaks it has been confirmed that all structures were organized as lamellas but with different d-spacing values. These particularities at micro- and nanoscale level lead to differences in rheological properties of organogels. Results showed that the oil type (i.e. medium- and long-chain triglyceride) and hydrophilic head of gelators (i.e. sorbitan versus glyceryl) exert influence on the organogels physical properties, but the presence of monostearate leads to the formation of stronger organogels. Moreover, gels produced with LCT were stronger and gelled at lower organogelator concentration than MCT.

Topics: Crystallization; Food Handling; Gels; Glycerides; Hexoses; Hot Temperature; Hydrophobic and Hydrophilic Interactions; Microscopy, Polarization; Molecular Structure; Nanoparticles; Organic Chemicals; Particle Size; Rheology; Scattering, Small Angle; Stearates; Surface-Active Agents; Time Factors; Triglycerides; X-Ray Diffraction

The binary mixtures involving tristearin (TS), stearyl stearate (SS) and stearic acid (SA) were studied by surface pressure-area (pi-A) measurements and by Brewster angle microscopy (BAM), at the air-water interface, and the Langmuir-Blodgett (LB) monolayers, transferred onto mica substrates, were analysed by AFM. The thermodynamic analysis indicated miscibility in the whole composition range for the system SA/TS, and partial miscibility for systems SA/SS and TS/SS. This behaviour was further confirmed by BAM observation and AFM analysis of LB films. The AFM imaging of collapsed monolayers revealed domains with a multilayered structure varying with system and composition. The layers thickness determined by cross section analysis are consistent with estimated molecular lengths and conformations proposed for the molecules, assuming nearly perpendicular or tilted orientations of the hydrocarbon chains to the interface.

Topics: Lipid Bilayers; Microscopy; Microscopy, Atomic Force; Phase Transition; Stearates; Stearic Acids; Surface Properties; Thermodynamics; Triglycerides; Waxes

Solid dispersions of morphine in tristearin, beta-sitosterol, and cholesterol were prepared by evaporation of their ethanol solutions. Weight ratios of morphine-lipid of 1:1, 1:3, and 1:4.5 were prepared. Dissolution studies of the solid dispersions and morphine were conducted in a simulated GI medium at 37 degrees. The release rates of morphine from the tristearin dispersions were the slowest. The 1:1 morphine-tristearin dispersion was administered orally to rats. Free and total morphine levels in rat urine were determined by spectrofluorometric and enzymatic immunoassay procedures, respectively. The morphine-tristearin dispersion yielded a higher percentage of free morphine after 24 and 48 hr as compared with morphine and its sulfate.

Topics: Animals; Inactivation, Metabolic; Lipid Metabolism; Male; Morphine; Rats; Solubility; Stearates; Stearic Acids; Triglycerides

Diets containing relatively homogeneous triglycerides composed of 18-carbon chain saturated, monounsaturated or polyunsaturated fatty acids were fed to rats. Cholesterol absorption and turnover were studied. Cholesterol absorption was significantly less in rats fed tristearin than in animals fed triolein or safflower oil. Cholesterol removal from plasma was fastest in rats fed tristearin and slowest with safflower oil and triolein. Plasma cholesterol levels were lowest with tristearin and highest with safflower oil. Increased cholesterol in high density lipoproteins was observed with tristearin and triolein. Lymph and hepatic cholesterol, and lymph triglycerides were highest with safflower oil, suggesting endogenous mobilization. Cholesterol production was least with triolein. Sterol synthesis was greatest with tristearin, perhaps attributable to decreased negative feedback analogous to effects of cholestyramine. Differences in lipoprotein composition observed with the various diets are important since effects on particle size and shape may influence removal mechanisms. The mechanisms underlying the different effects of dietary triglycerides on sterol absorption and metabolism remain to be elucidated.

Topics: Animals; Cholesterol; Dietary Fats; Kinetics; Lipoproteins; Liver; Lymph; Male; Oils; Rats; Safflower Oil; Stearates; Stearic Acids; Structure-Activity Relationship; Triglycerides; Triolein

Topics: Oils; Ointment Bases; Pharmaceutical Vehicles; Stearates; Triglycerides; Wounds and Injuries