The effect of rapeseed microstructure on the mechanism of solution and diffusion extraction

Autor: František Kreps, Jiri Stetina, Lucie Pustelnikova, Veronika Matlova, Vladimír Filip, Jan Kyselka, Štefan Schmidt, Pavel Ulbrich
Rok vydání: 2014
Předmět:
Zdroj: European Food Research and Technology. 240:853-863
ISSN: 1438-2385
1438-2377
DOI: 10.1007/s00217-014-2392-8
Popis: 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 m2 g−1) and small (1.5 ± 0.1 m2 g−1) 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.
Databáze: OpenAIRE