Influence of extraction methods on functional properties of protein concentrates prepared from South African bambara groundnut landraces

Functional properties of protein concentrates prepared from three bambara groundnut landraces using acid precipitation and salt solubilisation methods were evaluated. The protein content of bambara grains (26-27%) was similar for the three landraces. The acid precipitation gave a much higher yield of protein concentrates (52%), which were also high in protein (79%) compared to the salt solubilisation method (yield: 25%, protein content: 57%). Functional properties of proteins were more influenced by the methods of preparation rather than the landraces. Protein concentrate prepared by salt solubilisation method showed higher emulsifying (63-66%), foaming (53-57%), water (1.4-2.0mgmL(-1)) and oil absorption properties (2.2-2.6mgmL(-1)) than the acid-precipitated concentrates (53-57%, 63-66%, 2.0-2.7mgmL(-1), 1.4-1.7mgmL(-1)). The foaming capacity and stability of all the protein concentrates decreased with increasing pH from 3 to 8. Salt solubilisation may be the most appropriate method for the enhanced functionality and utilisation of bambara groundnuts' protein concentrates.