Lupine protein enzymatic hydrolysates obtained in a simultaneous extraction-hydrolysis process as foaming agents

In most experimental protocols described in the literature, a plant seed protein extraction and its enzymatic hydrolysis are separated. A simultaneous extraction and hydrolysis process was proposed as a much simpler and less energy-demanding alternative. The enzymatic lupine protein hydrolysates obtained in the simultaneous process were tested for their ability to produce and maintain foams, showing that the proposed process simplification did not compromise foaming properties of the hydrolysates. Two animal-sourced (trypsin and pancreatin) and one plant-sourced proteolytic enzyme (papain) were employed at variable specific enzymatic activity, ranging from 60 nkat/g protein (for pancreatin) to 189 μkat/g protein (for papain) and temperatures (37 °C, 50 °C and 65 °C, respectively). The enzymatic hydrolysis improved foaming properties of the extracts, both in the subsequent (when the extraction and the hydrolysis were performed in separated steps) and simultaneous (when the extraction and hydrolysis were taking place simultaneously) modes: foam capacity (FC) increased from ∼100 % to ∼270 % (for papain) with >50 % initial foam volume retained after 10 min. The obtained hydrolysates could be employed to provide a foaming activity of cosmetic, pharmaceutical or food products; when using the plant-sourced papain - also of the fully vegan ones. • Foam capacity (FC) of lupine seed extracts approximately doubled upon hydrolysis. • Combining extraction and hydrolysis does not compromise FC. • Trypsin, pancreatin and papain enzymes offer comparable results. • Foamable vegan lupine hydrolysates can be obtained using papain.