Extraction of protein from juice blend of grass and clover pressed by a pilot pressing facility combined with a pulsed electric field treatment

Abstract

In this work we report the new technical feasibility of combining a large-scale screw pressing facility with an industrial-scale pulsed electric field (PEF) system for a great increase in the yields of plant juice and crude protein extracted from freshly harvested blends of perennial ryegrass (Lolium perenne) (70%) and white clover (30%). A disk separator has been successfully utilized for continuous separation of 400 L of raw juice and successive protein precipitated at pH 5.0 and 60 °C. The yields of pressed juice and crude protein were increased by around 25% and 31%, respectively. The crude protein content reached 37.3 g/100 g in dry matter. In addition to the crude protein, the precipitated sediment contained minerals like Ca, K, Na, Mg and P, which are essential for health and promisingly interesting for future applications such as food alternatives. Microbial status, chemical compositions, macromolecular sizes and fat-protein microstructures of the samples collected at different process steps were explored, which allows for a better understanding of pilot-scale extraction processes and optimization. This study indicated a great potential for protein extraction from green biomass and for future food applications.