Influence of extraction conditions on the conformational alteration of pea protein extracted from pea flour

Plant proteins are becoming of increasing interest, since they are a more sustainable protein source than milk protein. One plant protein of interest would be pea protein. In contrast to milk proteins there has been less research done on extracting native pea proteins. Currently, commercial pea proteins are only available highly denatured and aggregated. There are three commonly used extraction methods on laboratory scale: alkali extraction with isoelectric precipitation, salt extraction and micellar precipitation. Within this study, these three extraction methods next to one modified production process and a commercial pea protein isolate were compared with each other focusing on conformational alteration during the extraction process. Solubility and particle size in combination with charge at different pHs and ionic strength and denaturation temperature and enthalpy change at pH 7 in 0.1 M NaCl and 1 M NaCl have been taken as indicators of conformational alteration. Differences in structure between the obtained protein products were observed. Albumins were lost during precipitation in alkali extraction – isoelectric precipitation and micellar precipitation. Solubility was highest for pH 3 and pH 8. Micellar precipitated protein product formed micelles at low ionic strength and solubility of these could be increased by addition of salt. It has been found, that both steps during the extraction process, solubilisation and precipitation, had an influence on the conformational alteration of the protein. Solubilisation had in impact on the denaturation of the protein. Precipitation had an impact on the protein profile and irreversible or reversible aggregation.