Saccharomyces cerevisiae, known as baker's or brewer's yeast, produces a complex mixture of proteins including enzymes, structural components, and metabolic proteins. These are extracted for nutritional supplements, flavoring, and functional food ingredients. Yeast proteins supply essential amino acids and are used in fermentation processes for baking and brewing. They exhibit diverse molecular weights from ~10 kDa to over 100 kDa and can modulate immune responses. As a food ingredient, they are valued for high protein content and digestibility. Individual proteins vary in solubility and functionality based on extraction methods and processing conditions.