Isolation of quinoa protein by milling fractionation and solvent extraction

Abstract Quinoa is an attractive non-animal protein source, because of its absence of gluten and the favorable amino-acid profile. The objective of this study was the extraction of quinoa protein by two consecutive approaches. Initially, the protein-rich bran was isolated by optimizing the conditioning parameters of a milling fractionation procedure. In contrast to the protein content of the whole grain, 11.75% in dry base (db), the bran fraction contained 27.78% (db) protein when conditioned with 15% moisture at 20° for 20 h. Subsequently, an aqueous extraction was developed, resulting in a protein solubility of 60% at pH 10 and 20° for 1 h. For purification at the isoelectric point, the pH-value and the separation method were varied. After drying, an extraction of proteins from bran yielded 68% (db) as compared to 52% (db) protein from quinoa whole grain flour.