Amino acids in yeast fermentation: A review of their roles from nutrients to modulators

Yeasts perform a critical and irreplaceable role due to their powerful and versatile metabolic capabilities in fermented food production. Beyond serving as mere nitrogen sources, amino acids present in fermentation systems are increasingly recognized as key modulators of yeast performance, regulating yeast physiology, flavor metabolism, and stress tolerance. A systematic understanding of amino acid-yeast interaction holds considerable theoretical and practical values. This review synthesizes current knowledge on the sources of amino acids in fermentation systems and their multifaceted regulatory roles on yeasts. Firstly, amino acids in fermentation systems originate dynamically from raw materials, enzymatic proteolysis, and microbial cell lysis. Yeasts employ sophisticated regulatory systems and specific transporters for selective amino acid uptake. Internally, amino acids are channeled into synthesizing key flavor compounds (e.g., higher alcohols, esters, and volatile sulfur compounds). Additionally, certain functional amino acids (e.g., proline and arginine) and their derivatives (e.g., glutathione) can enhance yeast tolerance under various environmental stresses. Despite advances, significant knowledge gaps remain concerning non-Saccharomyces yeasts and the heterogeneity of real fermentation environments. Future research integrating multi-omics, synthetic biology, and ecological modeling is essential to elucidate amino acid-yeast interactions for optimizing fermentation quality and efficiency.