Valorisation of protein-rich extracts from spent brewer’s yeast (Saccharomyces cerevisiae): an overview

As one of the main brewing by-products, Saccharomyces cerevisiae extracts (from spent yeast) have been commercialized as food supplement for years. Among their several claims, the application as protein source is highlighted. In fact, their high protein content (about 45–60%) including essential amino acids with high biological value, safety and low cost are primarily responsible for their spreading in agri-food sector. Meanwhile, cosmetic and health sectors have been working on yeast bioactive peptides because of their antihypertensive, antioxidant and antimicrobial properties, among others. Several studies related to valorisation of S. cerevisiae are currently ongoing, aiming to create novel products and optimize production processes. The present review aims to provide an overview from production of protein-rich extracts from S. cerevisiae to their chemical characterisation, detailing protein extraction, isolation and purification processes, as well as characterisation methods for the final extracts.