Pulsed electric field pretreatment of rapeseed green biomass (stems) to enhance pressing and extractives recovery

The objective of this study was to investigate the effects of pulsed electric field (PEF) pretreatment on the valorization of extractives (proteins and polyphenols) from rapeseed green biomass (stems) by pressing. The effect of pressure, electric field strength and pulse number on the juice expression yield, total polyphenols and total proteins content in the expressed juices were studied. Experiments conducted under optimal conditions (E = 8 kV/cm, t(PEF) = 2 ms, P = 10 bar) permitted to increase the juice expressed yield from 34% to 81%. Significant increases in total polyphenols content (0.48 vs. 0.10 g GAE/100 g DM), in total proteins content (0.14 vs. 0.07 g BSA/100 g DM) and in consolidation coefficient (9.0 x 10(-8) vs. 2.2 x 10(-8) m(2)/s) were also observed after PEF pretreatment. The recovered press cake was well dehydrated with an increase of dry matter content from 8.8% to 53.0%. (C) 2015 Elsevier Ltd. All rights reserved.