Physico-chemical characterization of ten commercial pea protein isolates

This study screened ten different commercial pea protein isolates in terms of composition including protein-, fat-, dry matter-, ash-, and sodium chloride content, color, molecular weight distribution, as well as functionality in aqueous suspension including solubility, native pH, water/oil holding capacity, and zeta potential. While composition did not differ strongly between the different protein isolates, excluding minor differences in protein and ash content, functionality did. Aqueous solubility ranged from 9.24% to 40.74%, native pH between 5.50 and 8.15, and water holding capacities between 2.52 g/g and 5.19 g/g. In addition, the oil holding capacity was also the lowest for the batch with the lowest water holding capacity with 1.33 g/g and the highest for the one with the highest water holding capacity with 2.21 g/g. A classification of solubility of commercial pea protein isolates was proposed with classes low (<10%), medium (similar to 20-25%) and high (>35%). Predictions regarding colloidal stability were possible due to the analysis of surface charge over a pH range of around 2.5 to 8, including the determination of the isoelectric points of the individual pea protein products. Here, differences were found between pH 3.43 and 4.76. An SDS-PAGE analysis was used to fractionate the main protein components and to determine the constituents in comparison with a standard marker. Taken together, this study showed that different pea protein isolates exhibited different physico-chemical properties, and that a selection for food product development based on the parameters such as solubility, zeta potential behavior, native pH, and water/oil holding capacity is advisable.