To clarify the tempering mechanism in solid-fats products, we measured solid content, average size and number of particles by the permeability method developed by us. In this study, we used margarine, shortening and standard sample before and after tempering treatment. Also, the microscopic structures of fats products were observed with a scanning electron microscope. The following results were obtained. (1) The solid particles in the fats before tempering were agglomerates of fine particles and fine particles dispersed in a certain temperature range, resulting in rapid decrease in average size of particles and increase in solid particle number. (2) Tempering caused marked changes in size and number of solid particles in solid-fats products, and these changes corresponded well to those of fats before tempering at certain temperature, as mentioned in (1). (3) The dispersion of constituent fine particles in agglomerates induced by tempering was caused by the change of fat crystals to more stable polymorphism.
Silica gels modified by alkoxyalcohols were prepared by refluxing silica gel and alkoxyalcohols in n-decane. Characterization of the modified silica gels was performed by FT-IR, DTA and elemental analysis. Benzyl bromide, n-hexyl bromide and dibromoethane reacted with potassium acetate in the presence of the modified SiO2 to give the corresponding acetates. Reduction of acetophenone, cyclohexanone, 1-indanone and 2-octanone with NaBH4 proceeded smoothly in the presence of the modified SiO2.
An isolated surfactant phase (microemulsion, D′) appeared near a water-surfactant axis in a water/dodecyl octaethylene glycol ether/1-dodecanol system. The D′ phase formed two types of three-phase triangles with excess water, lamellar liquid crystalline and reversed micellar solution phases. The solubilization of 1-decanol in the D′ phase was rather small. The composition in the D′ phase is independent from the temperature, whereas the composition in a surfactant phase (middle phase microemulsion, D) in a hydrocarbon system was changed from water-to oil-rich regions with increase in temperature. Judging from the electrical conductivity measurement, the structures of aggregates appear to be three-dimensional continuous bilayers in the D′ phase. A lamellar liquid crystal extended towards a water corner between the single D′ phase region and aqueous micellar solution phase region. The liquid crystals dispersed in water as vesicles in the dilute region. The correlation between the formation of the D′ phase and water-swollen lamellar liquid crystal is discussed.
Molecular dynamic simulations were carried out for liquid-vapor interface of n-pentane. Interactions among n-pentane molecules are represented by the Lennard-Jones potential function. In this calculation, the Gibbs surface is adopted. To simulate thermodynamic quantities at a liquid-vapor interface, 216 n-pentane molecules were set in a cubic box. At first, the surface energy (U) was calculated, and then surface tension (γ). Surface energy was obtained from the difference between surface potential energy (17 replicas) and bulk potential energy (26 replicas). Surface tension was determined using the equation U=γ-T (dγ/dT). In this calculation, the condition that γ=0 at critical temperature (470K) is introduced. From values of surface energy and surface tension, surface entropy was obtained. Surface energy was 50.80erg/cm2 and surface tension, 19.13dyn/cm. Deviation in surface tention from the experimental value was ca. 19.8%. Surface entropy was 0.108erg/K cm2.
A high-performance liquid chromatographic method with high sensitivity and selectivity for analysis of anionic surfactants (ASF) is described. ASF such as alkylbenzenesulfonate (LAS), alkanesulfonate (SAS), α-olefinsulfonate (AOS), alkyl sulfate (AS) and poly (oxyethylene) alkyl ether sulfate (ES) were separated by reversed-phase chromatography using ODS-silica (Hitachi gel 3053) as a stationary phase and 1mM sodium perchlorate in acetonitrile-water (30 : 70) as a mobile phase and were detected with non-suppressor type conductive detector. The calibration curve was linear in the range from 0.005 to 17μg for C12 AS-Na and the relative standard deviation with five measurements was 0.31% for 1.0μg C12 AS-Na. The results of homolog analysis of LAS by the proposed method showed good agreement with those by the UV detection. Nonionic, cationic and amphoteric surfactants did not interfere with the analysis of ASF. By the proposed method, ASF in commercial household and cosmetic products were analyzed with high sensitivity and selectivity. Better separations were achieved by the gradient elution method.