Physical, techno-functional and antioxidant properties of black cumin seeds protein isolate and hydrolysates

The present work aims to study physical, techno-functional and antioxidant properties of black cumin seeds protein isolate (BCSPI) and its hydrolysates (BCSPH). BCSPI and BCSPH were characterized by high contents of protein (78.4–83.5%). Thermal characterization by DSC showed that the denaturation temperature (Td) increased from 90.7 to 131.9 °C. BCSPI was characterized by the lowest Td. The highest Td was observed for BCSPH with a hydrolysis degree (DH) of 14.74%. The enzymatic hydrolysis was found to enhance protein solubility. BCSPH (lowest DH = 12.58%) exhibited significantly higher emulsifying and foaming properties than BCSPI. The above observation was probably relating to the decrease of interfacial tension from 28.50 to 25.67 mN/m (BCSPH).Antioxidant activities of BCSPI and BCSPH were assessed in vitro through different antioxidant tests. At a concentration of 1 mg/mL, BCSPH with higher DH (19.63%) exhibited significantly the greatest scavenging activity (90.82%) towards DPPH radical. Antioxidant activities were improved with the increase of the degree of hydrolysis. The obtained data suggest that the choice of the hydrolysis degree can improve the functional and the antioxidant activities of protein isolate. Overall, BCSPH have peculiar techno-functional and antioxidant properties which promote their use in food, cosmetic or pharmaceutical products as natural dietary proteins.