Protein isolates from chickpea (Cicer arietinum L.): chemical composition, functional properties and protein characterization

Two types of protein isolates were prepared from ground chickpea seeds by alkaline extraction, with (Isolate-B) and without (Isolate-A) sodium sulphite, and acid precipitation of the proteins at the isoelectric point (pI 4.3). The percentage of protein recovered from chickpea flour in the preparation of Isolates-A and B were 65.9 and 62.1%, respectively. Chemical composition, main functional properties and protein composition of chickpea flour and protein isolates were determined. Isolates-A and B contained 78 and 88.1% of protein, respectively, and had a balanced content of essential amino acids, with respect to the FAO pattern. The in vitro protein digestibility ranged between 95.6 and 96.1%. Isolate-A showed a partial dissociation of the 11S protein because of the high pH used for the protein extraction, and this probably explains the differences observed in the functional characteristics of both isolates.