Evaluation of the effect of spray and freeze drying techniques and different pH on the functional properties of protein isolate from chickpea (Cicer arietinum, var. Azad)

The functional properties of chickpea protein isolate (CPI) extracted by isoelectric precipitation and dried by spray- or freeze-drying methods were evaluated as a function of the change in protein structure. The maximum nitrogen solubility for both of freeze-dried and spray-dried protein (no significant difference (p > 0.05)) was obtained at pH 7 and increasing pH had no strong effect on solubility. Water absorption capacity of freeze-dried CPI was significantly higher (p < 0.05) than spray-dried one at pH 3 and pH 7 but oil absorbance capacity was inverse. The bulk density of freeze and spray-dried proteins was measured to be 0.546 +/- 0.01 g cm(-3) and 0.344 +/- 0.02 g cm(-3), respectively. Zeta potential, particle size distribution, emulsifying properties, foaming properties, interfacial tension as well as the surface hydrophobicity were shown to be strongly affected by pH and drying method. Based on the obtained results, the functional properties were positively correlated to the protein solubility. Moreover, the CPI was able to form gels when concentration exceeded 10 % (w/w). Chickpeas are a relatively rich source of protein (20-30 %) from which the protein extracted not only has considerable nutritional value, but also, as identified in this study, has comprehensive and appropriate functional properties. Also, CPI could be used as an effective ingredient for the formulations of food products because of acceptable foaming, emulsifying, gelling and other functional properties.