Effect of extraction methods on the physicochemical and functional properties of desi and kabuli chickpeas

Abstract: There is increasing demand for innovative and functional plant proteins. Chickpea is a pulse grain that is agronomically adaptable and rich in proteins. Kabuli (large cream-colored) and desi (small brown-colored) are the two main types of chickpeas. The study aims to understand the impact of various extraction methods and conditions on the physicochemical and functional properties of desi and kabuli chickpeas.

Chickpea grains were ground to fine powders with a laboratory roller mill, which were then defatted and used for protein extraction according to different methods, including salt extraction, alkaline extraction (pH 8.0, 9.0, 10.0, and 11.0, respectively) or deionized water at as-is pH (7.0) extraction, followed by isoelectric precipitation. The extracted proteins were neutralized and lyophilized, except that the protein from salt extraction was dialyzed to remove the salt and before lyophilization. The proteins were analyzed for SDS-PAGE profile, surface hydrophobicity, secondary structure, solubility, water/oil holding capacity and emulsification/foaming capacity and stability.

The desi flour (27.4%) had higher protein content than the kabuli flour (23.6%); however, the protein recovery rate from kabuli was around 5-15% higher than that from desi. The protein content from the salt extraction (91-93%) was much higher than that from other methods (80-85%). The salt extracted proteins were much less soluble compared to those from other methods at pH 7. The salt extracted kabuli protein had the lowest foaming capacity compared to the proteins from other conditions, while the salt extracted desi protein had modest foaming properties. All the proteins possessed good emulsification properties. SDS-PAGE results revealed that the kabuli and desi extracts had similar protein profiles; however, protein compositions varied slightly from the different extraction methods. This study provides valuable information to guide future production and food application of chickpea proteins.