Technofunctional Profile of Brewer’s Spent Yeast Extracts Obtained through “Green” Extraction Processes.

Spent yeast represents the second most important by-product of the brewing industry. This abundant yet underexplored biomass is a reservoir of valuable compounds with potential applications in the food and pharmaceutical sectors. To add value to this biomass, extraction processes can be performed, given the presence of technologically relevant compounds such as polysaccharides, proteins, and bioactive molecules. This approach contributes to sustainable practices aligned with the principles of the bioeconomy. This study aimed to evaluate the technofunctional profile of residual yeast extracts from the brewing industry, Saccharomyces cerevisiae and S. pastorianus, obtained through microwave-assisted and thermosonication (MT) processes. The residual biomass was subjected to sequential extraction using water as a solvent. The process began with autolysis (60°C, 2 h), followed by enzymatic inactivation (90°C, 30 min) and three cell disruption protocols: (1) Thermosonication and mechanical agitation (40 kHz, 70°C, 30 min); (2) Microwave (460 W, 3 min) combined with thermosonication and agitation; and (3) Sonication and agitation. After centrifugation, the supernatants were freeze-dried and analyzed for emulsifying properties at pH 2, 4, and 7, and foaming capacity at pH 3 and 7. The results showed an increase in emulsifying activity with rising pH values, with the highest activity observed at pH 7 for S. cerevisiae extract. Regarding emulsion stability, both extracts obtained through the MT protocol exhibited greater stability at pH 4 (~73%). Foam-forming capacity was high, showing greater performance under acidic conditions for S. cerevisiae extract and under neutral conditions for S. pastorianus extract. A similar trend was observed for foam stability, with MT extracts exhibiting superior stability (S. cerevisiae: 42%; S. pastorianus: 48%). The cavitation generated by sonication (SNC) promoted the rupture of protein aggregates and reduction of particle size, increasing solubility, surface hydrophobicity, and specific surface area of proteins. These effects enhanced protein adsorption at oil–water interfaces, improving emulsifying properties. SNC may also modify protein secondary structures, contributing to foam formation and stability. Microwave treatment provided rapid and uniform thermal action, promoting partial protein denaturation and release of soluble polymers, favoring emulsification and foaming behavior. These findings demonstrate the technofunctional potential of these extracts for food industry applications, contributing to waste valorization and the implementation of green and sustainable processing technologies.