Enhancing the sustainable protein extraction process from black cumin seed cake press for eco-friendly protein supplements

Finding new protein sources is essential to meet the global population's needs. Nigella sativa (black cumin) seeds and the residual cake left after oil cold pressing contain valuable nutritional compounds, including proteins, phenolics, essential amino acids, and various bioactive compounds. In the literature, the structural characteristics and functional properties of proteins from black cumin seeds have been extensively studied. However, there are limited reports on the use of emerging extraction technologies for extracting soluble proteins from black cumin seed cake press (BCSCP). Therefore, two distinct extraction techniques-microwave (MW) and ultrasonication (US)-were assessed for their effectiveness in extracting soluble proteins from BCSCP. The aim of this study was to investigate the effects of various operational conditions on protein extraction yield and functional properties of proteins extracted from BCSCP. The maximum protein yield (27.04%) was achieved using a 10% solid/liquid ratio (SLR) at 33 degrees C for a 30-min extraction time with the US extraction technique. After ultrafiltration, the protein yield increased to 33.83%, showcasing the predominance of sarcosine (17.18 g/100 g), glutamine (11.63 g/100 g), and proline (33.46 g/100 g) amino acids. The water-holding capacity (WHC), oil-holding capacity (OHC), foam capacity (FC), and foam stability (FS) of the BCSCP isolate were found to be 5.4 +/- 0.3 g/g, 9.4 +/- 0.0 g/g, 43.6 +/- 6.4%, and 39.0 +/- 4.7%, respectively. The study revealed that US is a suitable extraction process for obtaining soluble proteins from BCSCP with favorable functional properties. Further studies are needed to evaluate the bioavailability and health impacts of bioactive peptides in order to develop food applications.