AbstractBACKGROUNDLinseed fractionation was performed in laboratory scale to obtain concentrated protein and fiber fractions. Three methods were tested to obtain the linseed protein concentrate (LPC). The isoelectric pH method was more efficient in increasing the protein content and also provided higher yield. In the fractions obtained, the chemical composition (dry matter, ash, lipids, crude protein, total dietary fiber, calcium and phosphorus), total phenolic compounds and the physicochemical properties were evaluated. The profile of amino acids was determined for linseed meal and LPC, and the profile of monosaccharides was evaluated for linseed grain, soluble and insoluble fractions of the fiber.RESULTSThe results indicated that the protein concentration method by isoelectric pH improved the amino acidic profile and in vitro digestibility of LPC. The fractioning of the linseed fiber was efficient, since the soluble fiber of the soluble fraction corresponded to 675 g kg−1. The separation of the fiber from the linseed concentrated the phenolic compounds in the insoluble fraction. For linseed grain there was a higher concentration of glucose, followed by xylose, galacturonic acid and arabinose. The same monosaccharides were identified in the insoluble fraction, with the exception of arabinose. In the soluble fraction, higher levels of xylose were found, followed by glucose, galacturonic acid and arabinose.CONCLUSIONThe present study allows us to conclude that it is possible to separate the linseed into different fractions, obtaining a protection concentrate and fibers. The inclusion of these products in animal feed needs to be evaluated to determine levels of acceptance. © 2021 Society of Chemical Industry.