Tailoring techno-functional properties of lupin protein isolates by means of different pH-shift extraction conditions.

The diversification of protein sources is essential to meet the growing global demand for protein in a secure and sustainable manner. In Europe, lupin (Lupinus spp.) stands out as a promising candidate due to its high protein content, low agronomic requirements, and potential to strength food system sovereignty and sustainability. The functionality of protein isolates is crucial in developing plant-based food products, as their techno-functional properties – such as, solubility, emulsification, foaming, and gelling capacities – play a key role in determining their suitability for various food applications.

This study investigates the effect of specific technological parameters—salt concentration, heat treatment, and high alkaline pH—applied during the alkaline solubilization stage of lupin protein isolation. The aim was to elucidate the physicochemical and structural modifications induced by these conditions and their subsequent impact on the techno-functional properties of the isolates.

The findings demonstrate that heat treatment improves protein mass and extraction yield while enhancing emulsifying and gelling properties. In contrast, salt-assisted extraction yields lower protein recovery but markedly enhances solubility and foaming capacity. Comparative analysis with a commercial soybean protein isolate revealed that lupin protein isolates obtained under specific extraction conditions exhibit superior techno-functional attributes. Structural characterization revealed that salt-assisted extraction preserves elevated hydrophobicity and free sulfhydryl groups. Conversely, heat treatment reduces these groups, leading to increased disulfide bond formation.

These results underscore the potential of tailoring lupin protein isolates’ techno-functional properties through precise modulation of wet extraction parameters. This approach provides a robust framework for developing high-performance, sustainable ingredients for plant-based food systems.