Limited proteolysis as a tool for the improvement of the functionality of sunflower (Helianthus annus L.) protein isolates produced by seeds or industrial by-products (solvent cake)

Protein isolates were extracted by different procedures, isoelectric precipitation and ultrafiltration, and also isolated by limited enzymatic treatment with trypsin. Their functional properties were studied, namely surface pressure, foam capacity and stability and emulsion mean oil droplet size and viscosity. The influence of pH value, the addition of NaCl and xanthan gum were also studied.Results revealed that the limited proteolysis isolate was very effective in stabilizing emulsions and foams. Furthermore, the addition of NaCl enhanced foam ability while the addition of xanthan gum improved foam stability. The limited proteolysis isolate had better emulsifying and foaming properties than had the native isolates.