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Here, we present the effect of rapeseed microstructure on the extraction mechanism. 'Solution and diffusion' extraction had to be considered to deepen the understanding of the process. Transmitted light microscopy images of the ultramicrotome-cut casting sections proved the presence of 'conductive' capillary system with radius R from 8 to 25 μm. The rate of 'solution extraction' was controlled by capillary flow through 'conductive' voids. It was described by derived and extended Hagen-Poiseuille equation. The rate of solvent extraction of soybeans was described by negative power function, whereas rapeseed extraction was defined by complex nonlinear curve-fitting model. Specific surface area of large (1.3 ± 0.1 m g) and small (1.5 ± 0.1 m g) fraction of rapeseed extraction meal particles did not differ significantly, contrary to flaked soybeans. This is the novel finding. Significant differences could be explained by vegetable seed histology context (seed and cell size, sorption abilities). 'Diffusion extraction' was rate determining at the flat part of the time-dependent extraction curve. Isolated fraction of free fatty acids originated from simultaneous lipolysis of acylglycerol species and hydrolysis of glycerophospholipids and glyceroglycolipids. Decreasing quality of last fractions increased refining loss and material costs. Compounds such as waxes (6.89-10.40 wt%), complex glycerolipids (14.83-15.26 wt%), and free fatty acids (2.26-2.45 wt%) had to be removed by edible oil refining. [ABSTRACT FROM AUTHOR]

Abstract: The binary phase behavior of purified 1,3-dilauroyl-2-stearoyl-sn-glycerol (LSL) and 1,2-dilauroyl-3-stearoyl-sn-glycerol (LLS) was investigated at a slow (0.1°C/min) and a relatively fast (3.0°C/min) cooling rate in terms of melting and crystallization, polymorphism, solid fat content (SFC), hardness and microstructure. Much of the behavior of the system is explained by its polymorphism and the influence of thermal processing. The α-form and the β′-form of a double chain length structure were detected in the mixtures cooled at 3.0°C/min, whereas only the β′-form was detected in those cooled at 0.1°C/min. X-ray diffraction data as well as thermodynamic data propose that the most stable phases are promoted by the symmetrical LSL. The measured trends in structural characteristics, thermal properties, SFC, relative hardness and microstructure delimit three groups of mixtures which imply a competition between the stabilizing effect of LSL and disordering introduced by kinetic effects: (a) LLS-rich mixtures with LSL molar fractions (X LSL) less than 0.3, (b) mixtures with X LSL clustered around 0.5 and (c) LSL-rich mixtures with X LSL ≥0.7. The balance between ordering and kinetic effects determines the polymorphism of the mixtures, which in turn determines the behavior of the LSL/LLS system. The kinetic phase diagram of the LSL/LLS binary system constructed using heating differential scanning calorimetry thermograms displayed a singularity at the 0.5LSL molar fraction which delimits two distinct behaviors: eutectic behavior in one region and monotectic behavior in the other. The molecular interactions, as depicted by a non-ideality parameter of mixing obtained from a thermodynamic model based on the Hildebrand equation, suggests an almost ideal mixing behavior and a moderate tendency to the formation of unlike-pairs in the liquid state. [Copyright &y& Elsevier]