Waste yeast of the genus <i>Saccharomyces</i> from the beer, wine, and sugarcane ethanol industries: valorization pathways and perspectives for the production of food ingredients

Yeast plays a central role in several industrial fermentation processes, including large-scale beer, wine, and ethanol production. Although widely recognized for its fermentative efficiency and robustness, its residual biomass-often discarded or underutilized-represents a rich source of valuable compounds. These include cell wall components such as β-glucans and mannans, which exhibit significant nutritional, functional, and technological properties. The expansion of these fermentation processes has resulted in an abundance of excreted yeast biomass, much of which is used in animal feed or discarded as waste. This review explores the valorization pathways of residual biomass from yeasts of the genus <i>Saccharomyces</i> from the brewing, wine, and sugar-alcohol industries, highlighting recent advances in extraction, biosorption, and microencapsulation methods for the development of food ingredients. Future perspectives include the integration of biorefinery approaches and circular bioeconomy models to increase the sustainability and economic viability of the use of biomass processes. By advancing the understanding and use of spent yeast, this work exposes the current scenario and future challenges in valorizing this raw material.