Detection of pressed hazelnut oil in virgin olive oil by analysis of polar components: improvement and validation of the method

An improved method for the detection of pressed hazelnut oil in admixtures with virgin olive oil by analysis of polar components is described. The method. which is based on the SPE-based isolation of the polar fraction followed by RP-HPLC analysis with UV detection. is able to detect virgin olive oil adulterated with pressed hazelnut oil at levels as low as 5% with accuracy (90.0 +/- 4.2% recovery of internal standard), good reproducibility (4.7% RSD) and linearity (R-2: 0.9982 over the 5-40% adulteration range). An international ring-test of the developed method highlighted its capability as 80% of the samples were, on average, correctly identified despite the fact that no training samples were provided to the participating laboratories. However, the large variability in marker components among the pressed hazelnut oils examined prevents the use of the method for quantification of the level of adulteration. (C) 2003 Elsevier Ltd. All rights reserved

A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

A coupled thermomechanical, thermal transport and segregation analysis of aluminum alloys solidifying on uneven surfaces is presented here. Uneven surfaces are modelled as sinusoids with different wavelengths and amplitudes. Effects of various coupling mechanisms between the solid-shell deformation, air-gap formation, heat transfer, fluid flow and segregation, near the mold-metal interface, are observed for different mold topographies during the early stages of solidification of an aluminum alloy. The role of inverse segregation, arising from shrinkage driven flow in the melt, melt superheat and varying mold surface topography on nucleation of air-gaps and evolution of stresses in the solidifying shell is examined. The numerical model consists of a volume-averaged solidification model coupled with a small-deformation model combining elasto-viscoplastic deformation in the solidifying shell with air-gap nucleation and imperfect contact at the metal/mold interface. Heat transfer at the mold-metal interface is either contact pressure or air-gap dependent and is modelled using the actual contact pressure or air-gap size obtained from the contact sub-problem at the metal-mold interface. Variation in heat transfer leads to variations in fluid flow, segregation and stresses developing in the solid and mushy-zone, which in turn affect the morphology of the growing solid-shell. A wavelength range that leads to a reduction in equivalent stresses, segregation and growth front morphology unevenness, in the evolving solid-shell, is obtained for varying solute concentrations. One of the main objectives of the current analysis is to seek optimal mold surface topographies that minimize surface defects leading to desired cast surface morphologies

A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

Solidification of Aluminum alloys is modeled on uneven surfaces characterized by sinusoidal curves. Wavelengths and amplitudes of these surfaces are varied to study the effect of changing surface topography on fluid flow, macrosegregation and inverse segregation in the solidifying alloy. Solidification is initiated by convective heat removal from the uneven surfaces and simulations are carried out in both vertical and horizontal configurations. Stabilized finite element methods, recently used for modeling solidification in the presence of shrinkage and buoyancy driven flows, are used to discretize and solve the governing transport equations derived by volume averaging. The effect of varying amplitudes and wavelengths is observed in heat transfer, fluid-flow, macrosegregation and inverse segregation processes. In vertical solidification, inverse segregation, that usually occurs at the bottom of the cavities, is studied for different sinusoidal topographies quantified by a particular wavelength and amplitude. The fluid flow here is driven by a combination of shrinkage and thermosolutal buoyancy. Shrinkage driven flow arises due to different densities of solid and liquid phases. During horizontal solidification of an Aluminum alloy from uneven surfaces, thermosolutal buoyancy plays a dominant role in fluid flow and the effect of shrinkage is neglected by assuming the individual phase densities to be equal. Convection in this case is much stronger than that in the vertical case and large scale redistribution of the solute element occurs. To measure variation in macrosegregation with changing surface topography, global extent of segregation and difference between maximum and minimum solute concentrations are calculated for different amplitudes and wavelengths. In both the cases, the main aim is to quantify changes in macrosegregation due to changing surface topography accomplished by varying amplitudes or wavelengths or both

A Combined Experimental and Computational Approach for the Design of Mold Topography that Leads to Desired Ingot Surface and Microstructure in Aluminum Casting.

A design methodology will be developed with which casting mold surface topographies can be tuned to produce required surface features and micro-structural properties of Aluminum ingots. Both static and continuous casting processes will be examined with instrumented molds. Mold surface topographies, which consist of unidirectional and bi-directional groove textures, will be generated using contact and non-contact techniques to elicit a radiator-like effect at the mold-casting interface. The rate of heat extraction, the evolution of near-surface cast microstructure, and shell macro-morphology can be controlled once the proper balance between mold surface area extension and the degree of imperfect wetting at the instant solidification starts is determined. Once this control is achieved, it will be possible to minimize or even eliminate costly post-casting surface milling or scalping which is currently a major barrier to the development of new Aluminum casting processes

Characterization of Date (Deglet Nour) Seed Free and Bound Polyphenols by High-Performance Liquid Chromatography-Mass Spectrometry

Date (Pheonix dactylifera L.) seeds are a valuable and abundant by-product with various potential food applications. Free polyphenols (FPPs) and bound polyphenols (BPPs) of date seeds from Deglet Nour variety grown in Australia were investigated using high-performance liquid chromatography-mass spectrometry. The FPP fraction contained the following main phenolic compounds per gram of date seed powder; procyanidin B1 (499.8 ± 7.8 μg), procyanidin B2 (288.6 ± 6.1 μg), catechin (167.6 ± 2.1 μg), epicatechin (39.44 ± 0.39 μg), and protocatechuic acid (1.77 ± 0.22 μg). Additionally, one of the 2 A-type dimers was confirmed as procyanidin A2 (24.05 ± 0.12 μg/g). A-type dimers have not been reported before in date seeds. The BPP fraction contained epicatechin (52.59 ± 0.76 μg/g) and procyanidin B2 (294.2 ± 3.7 μg/g), while several peaks exhibiting ESI- m/z of 153 indicated dihydroxybenzoic acid isomers including protocatechuic acid (2.138 ± 0.025 μg/g). These findings contributed to our knowledge of date seed phytochemicals and understanding of their contribution to the reported bioactivities