Pilot-Scale Protein Recovery from Cold-Pressed Rapeseed Press Cake: Influence of Solids Recirculation

Abstract

The agricultural sector is responsible for about 30% of greenhouse gas emissions, and thus there is a need to develop new plant-based proteins with lower climate impact. Rapeseed press cake, a by-product from rapeseed oil production, contains 30% high-quality protein. The purpose of this study was to recover protein from cold-pressed rapeseed press cakes on a pilot scale using a decanter and investigate the effect of recirculation of the spent solids fraction on protein yield. Proteins were extracted under alkaline conditions (pH 10.5) followed by precipitation at pH 3.5. Recirculating the spent solids fraction once increased the accumulated protein yield from 70% to 83%. The efficiency of the recovery process was highest in the first and second cycles. The additional yield after the third and fourth cycles was only 2%. The amino acid composition showed high levels of essential amino acids and was not reduced throughout the recovery process. The glucosinolate and phytate content was reduced in the precipitate after one cycle, although additional process steps are needed to further reduce the phytate content and limit the negative effect on mineral uptake.