Protein Fractionation of Leafy Green Biomass at the Pilot Scale: Partitioning and Type of Nitrogen in the Fractions and Their Usefulness for Food and Feed
Anna-Lovisa Nynäs, Emilia Berndtsson, William R. Newson, Helena Persson Hovmalm, Eva Johansson
Abstract
Fractionation of green biomass often results in fractions with insufficient protein content or quality for food or feed. To understand ways forward, we evaluated the fate of nitrogen (N) and the food or feed suitability of six pilot-scale fractions. The N was present mainly as amino acids (AA) in all fractions (<87%), however, the protein was partly degraded or insoluble in the majority of samples. All protein types and AAs traveled similarly through the fractionation process, giving insignificant separation of RuBisCO versus other proteins, and essential versus nonessential AAs. Water-soluble N compounds were enriched in juice fractions (90–95%), while the protein fractions contained the highest insoluble protein content (13–17%). AA composition in pulp and green juice verified their suitability as feed for ruminants and pigs, respectively. Fractionation of green biomass for food and feed is indeed important, although for sustainable industrial applications, further evaluations are required regarding process feasibility, antinutritional components, and brown juice uses.