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Influence of Extraction Processing on Rheological Properties of Rapeseed Oils
Author(s) -
Liu Changsheng,
Yang Mei,
Huang Fenghong
Publication year - 2012
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-011-1892-y
Subject(s) - rapeseed , rheology , viscosity , erucic acid , chemistry , shear rate , viscosity index , solvent , extraction (chemistry) , food science , chromatography , materials science , organic chemistry , base oil , composite material , scanning electron microscope
Rheological behavior of six crude rapeseed oils with different extraction methods including hot‐pressing, solvent‐extraction and cold‐pressing were studied. Viscosities of the oils were measured with shear rates ranging from 0.1 to 200 s −1 at three different temperatures. The Casson model was used to fit the experimental data and the Arrhenius equation was applied to estimate the energy of activation for viscosity ( E a ). The extraction methods affected the total tocopherol, total phytosterols, total phenols, phosphorus and fatty acid composition. The hot‐pressed medium‐erucic rapeseed oil (HMRO) had the greatest viscosity, and the cold‐pressed low‐erucic rapeseed oil (CLRO) had the lowest viscosity among all the oils with shear rates >5 s −1 at 10 °C. The crude rapeseed oils exhibited Newtonian behavior at higher shear rates. The significant difference of viscosity of the six oils was reduced with increasing temperature, and there was no significant change ( P > 0.01) among the oils with a shear rate of 100 s −1 at 50 °C. According to the values of E a , the following order of a change in viscosity was obtained as follows: CMRO > SMRO > HMRO > CLRO > SLRO > HLRO(C, cold pressed; S, solvent extracted; H, hot pressed; M, medium erucic; L, low erucic; RO, rapeseed oil). Minor components may be the contributing factors for the values of E a of rapeseed oils. The higher shear limiting viscosity (η c ) values calculated by the Casson model decreased as the temperature increased, but no significant change ( P > 0.01) was observed for η c by using different extraction methods at 50 °C.