Efficient yeast inactivation and protein extraction from wine lees using pulsed electric fields and ultrasound: a comparative energy-based approach

The valorization of wine lees, a major by-product of winemaking, is gaining attention as part of broader initiatives to promote circular economy and sustainable resource use in the agri-food sector. This study assessed ultrasound (US), pulsed electric fields (PEF), and their combination (PEF + US) as non-thermal technologies for promoting yeast autolysis and recovering intracellular proteins from wine lees. All treatments effectively reduced yeast viability, with populations decreasing from ~7.0 to ~4.7 log CFU/mL within 5 min. PEF alone achieved this microbial inactivation with a low energy input of 25–100 kJ/kg. In contrast, US yielded the highest protein release (~5700 μg/mL after 20 min), although it required a substantial energy input (~19,800 kJ/kg). The combined PEF + US method provided comparable protein yields (~5400 μg/mL) while reducing energy consumption by more than 50%. These results demonstrate that PEF is the optimal method for low-energy microbial inactivation, whereas US and PEF + US are more effective for protein recovery. The synergy of the combined approach offers a balanced and scalable solution for sustainable bioprocessing, reinforcing the potential of hybrid technologies in the green extraction of wine industry by-products and their integration into circular bioeconomy strategies.