Physicochemical, thermal and functional characterisation of protein isolates from Kabuli and Desi chickpea (Cicer arietinum L.): a comparative study with soy (Glycine max) and pea (Pisum sativum L.).

Background: Chickpea (Cicer arietinum L.) seeds are a good source of protein that has potential applications in new product formulation and fortification. The main objectives of this study were to analyse the physicochemical, thermal and functional properties of chickpea protein isolates (CPIs) and compare them with those of soy (SPI) and pea (PPI) protein isolates.

Results: Extracted CPIs had mean protein contents of 728-853 g kg(-1) (dry weight basis). Analysis of their deconvoluted Fourier transform infrared spectra gave secondary structure estimates of 25.6-32.7% α-helices, 32.5-40.4% β-sheets, 13.8-18.9% turns and 16.3-19.2% disordered structures. CPIs from CDC Xena, among Kabuli varieties, and Myles, among Desi varieties, as well as SPI had the highest water-holding and oil absorption capacities. The emulsifying properties of Kabuli CPIs were superior to those of PPI and Desi CPIs and as good as those of SPI. The heat-induced gelation properties of CPIs showed a minimum protein concentration required to form a gel structure ranging from 100 to 140 g L(-1) . Denaturation temperatures and enthalpies of CPIs ranged from 89.0 to 92.0 °C and from 2.4 to 4.0 J g(-1) respectively.

Conclusion: The results suggest that most physicochemical, thermal and functional properties of CPIs compare favourably with those of SPI and are better than those of PPI. Hence CPI may be suitable as a high-quality substitute for SPI in food applications.