Functional properties of Grass pea protein concentrates prepared using various precipitation methods.

Pulses are an affordable source of proteins, starch, lipids, minerals and high value nutritional sources. This study was conducted to evaluate relationship between protein functional properties and their preparation methods. Therefore, the functional properties of Grass pea protein concentrates (GPPC) prepared using isoelectric precipitation (IE), salt extraction (SE) and ultrafiltration-diafiltration methods (UF/D) were determined. The GPP processed by those three precipitation methods contained all of the amino acids which aspartic acid and glutamic acid were dominate amino acids followed by arginine and leucine. However, methionine and tryptophan were limited amino acids. Water binding capacity was in following order: UF/D-GPPC > SE-GPPC > IE-GPPC. Meanwhile, highest value of oil binding capacity belonged to UF/D-GPPC. GPPC prepared using UF/D method had highest solubility. In term of interfacial tension, it was revealed that the interfacial tension of all isolates did not significantly reduced (P > 0/05). Net negative zeta potential with values was observed which IE-GPPC had highest surface charge followed by UF/D-GPPC and SE-GPPC, respectively. In terms of surface hydrophobicity, it was altered in the following order: IE-GPPC > SE-GPPC > UF/D-GPPC. It was observed that foaming capacity ranged between 85.06 and 89.78% and foaming stability ranged between 77.34 and 84.35%. Emulsifying capacity, emulsifying activity index and emulsifying stability index ranged between 105.06-109.78%, 31.09-36.29 m(2)/g and 12.90-18.86 min respectively. Evaluation of least gelling concentration showed that UF/D-GPPC were capable to form firm gel at low concentration (10% W/V). The functional properties of proteins are influenced by their extraction technique and can be achieve maximum functional characteristics by selecting appropriate extraction method. The results indicated the technological potential of GPP for health-promoting food formulations.