Separation of oil from rapeseed protein rich extracts by microfiltration using hydrophilic ceramic membranes

Abstract

Rapeseed, containing up to 40 % protein along with a well-balanced profile of essential amino acids, stands out as a promising novel plant-based protein source. Yet, protein extraction faces challenges, due to adverse effects of oil extraction on protein properties and down-stream processing. In this work was explored the potential of using hydrophilic silicon carbide ceramic (SiC) membranes to separate oil from a protein rich extract and produce permeates rich in protein and retentates containing oleosomes. Various solvents including water, sodium chloride, alkaline (pH 8.5) and a complex alkaline salt solvent were used to obtain a variety of protein and oil extracts from the whole rapeseeds. The type of solvent significantly affected the composition and colloidal structure of the feed which has minor effect on the oil separation but significant effect on filtration performance and composition of the permeates and retentates obtained. The membrane filtration process achieved significant oil separation, with permeates exhibiting minimal oil content ranging from 0.1 to 1.3 % (w/w), for water and alkaline solvents respectively. Assessment of the filtration performance showed fluxes from 23 to 50 L·h⁻¹·m⁻² and final volume concentration ratios of 1.3, 1.4, 1.6 and 1.9 for salt, alkaline-salt, alkaline and water solvents. The retentate, composed of 11.8–19.8 % protein and 23.6–28.7 % w/w dry matter, is a relevant and innovative ingredient for plant food formulations. These findings show the potential of membrane filtration with SiC in enabling removal of oil and producing streams with potential for diverse applications in the food industry.