Comparison of the functional properties of pea, chickpea and lentil protein concentrates processed using ultrafiltration and isoelectric precipitation techniques

Abstract

In this study, two methods, isoelectric precipitation (IEP) and ultrafiltration (UF) were optimised for the extraction of proteins from yellow pea, desi and kabuli chickpeas, red and green lentils. For IEP, the following optimal extraction conditions were used: pH 9.5, 1/15 solid/liquid ratio, 35 °C for yellow pea, desi and kabuli chickpeas, and pH 9.0, 1/10 solid/liquid ratio, 25 °C for red and green lentils. UF experiments were performed with a 50 kDa MWCO membrane with diafiltration (4X) at pH 6.0. The initial protein content of the pulses (16.7–24.8%, w/w) was concentrated nearly 4-fold. UF process generated concentrates with slightly higher protein contents (69.1–88.6%, w/w) compared to the IEP process (63.9–81.7%, w/w). Yields for both processes on a protein basis ranged from 50.3% to 69.1% (w/w). All concentrates exhibited good functional properties. However, functional properties varied to some extent as a function of the type of pulse and manufacturing process. For pH ranging from 1 to 3 and from 7 to 10, the red and green lentil concentrates were the most soluble (70–77%) and their UF concentrates were more soluble at all pH values studied compared to the IEP samples which was not the case for the pea and chickpea samples. Water holding capacity was highest for IEP-processed yellow pea and lowest for the UF-processed desi and kabuli chickpeas. Emulsifying properties and foam expansion were generally higher for the chickpea concentrates but they had less foam stability. Protein extracts from green lentils appeared to have the best gelling properties. The results highlight the technological potential of pulse protein extracts for food applications.