Evaluating various Nitrogen Fractions and functional properties of Chickpea (Cicer arietinum) protein isolate

Chickpea (Cicer arietinum L.) seeds are important sources of food proteins. Apart from their nutritional properties, pulse proteins also possess functional properties that play an important role in food formulation and processing. In the present study, the effect of protein extraction pH from kabuli chick pea seeds on solubility, emulsion properties, water absorption capacity and variety nitrogen fractions of isolates were obtained from two extraction methods including alkaline extraction and acidic extraction. In this research, the protein was extracted at pH=2.5 and pH=9.5 and after that the protein was precipitated at Isoelectric point (pH =4.5). All experiments were performed in triplicates and Duncan multiple range test with a confidence interval of 95% was used to compare the means. Protein solubility was studied at pH 2.5 7.0. Environment pH had significant effect on solubility (p≤0.05). The solubility-pH profile of different protein isolates showed minimum solubility in the pH 4.0 and 5.0 and maximum solubility at pH 7 and afterward at pH 2.5, also protein isolates obtained by acidic method (isolate A) had higher solubility than protein isolates obtained by alkaline method (Isolate B). Both two isolates had suitable emulsion properties and water hold capacity. Isolate obtained by acidic method higher emulsification while alkaline method enhanced water absorption capacity (p≤0.05). Electrophoresis of the various fractions revealed that chickpea globulin was made up of sub-units of different molecular weights ranging from 10 to 150 kDa. bands corresponding to molecular weights of 30-40 kDa, which should be attributed to the acidic subunits of the 11S globulin (legumin), while the bands at about 25 kDa probably corresponded to the basic legumin subunit. Bands density of isolate B were thicker, this phenomena could be attributed to nearby of pH utilization for protein extraction at optimum pH of globulin extraction. According to suitable functional properties of chick pea protein isolate, it could be used as a novel protein source substitution in food productions.