Process Biochemistry, Vol.45, No.2, 247-258, 2010
Effect of enzymatic and hydrothermal treatments of rapeseeds on quality of the pressed rapeseed oils: part II. Oil yield and oxidative stability
Response surface methodology was used to evaluate the quantitative effects of three independent variables: rapeseed moisture content (MC), enzymes dosage (ED) and conditioning temperature (7) on rapeseed oil yield (OY), efficiency of pressing (EP), and oxidative stability (OS). The highest OY (16.4%) and EP (42.8%) were obtained from pectolytic enzyme (0.1%) treated seeds (MC = 9%. T= 90 degrees C). The highest OS (12.6 h) was found for oil pressed from rapeseeds heated at 120 degrees C (MC = 11%), after the cellulolytic enzyme treatment. Results of OY, EP and 05 determinations correlate with the predicted values calculated from the partial cubic models (PCMs) equations (R(2) = 0.9995, 0.9994, 0.9974 for the cellulolytic enzyme-treated oils and 0.9900, 0.9900, 0.9990 for the pectolytic enzyme-treated oils). The predicted optimum MC 9.5% and 8.6%, ED = 0.06% and 0.1%, T = 91.2 degrees C and 90.1 degrees C resulted in OY = 15.5% and 16.5%, EP 40.4% and 43.0% for rapeseed oils from seeds treated with cellulolytic and pectolytic enzymes. OS values (12.6 h and 11.8 h) at the optimum conditions of MC = 11.0% and 10.1%, ED = 0.04% and 0.08%, T = 120.0 degrees C and 119.9 degrees C for the cellulolytic and pectolytic enzyme-treated oils were also calculated using PCM. Moreover, scanning electron microscopy revealed structural changes in the rapeseed after enzymatic treatment. (C) 2009 Elsevier Ltd. All rights reserved.
Keywords:Enzyme-pressed rapeseed oils;Oil yield;Oxidative stability;Response surface methodology;Scanning electron microscopy