Yeast-Derived Esters in Wine: Biosynthesis, Regulation, and Metabolic Engineering

Esters are among the most significant volatile aroma compounds in wine, contributing predominantly to its fruity and floral notes. Acetate esters and medium-chain fatty acid ethyl esters are particularly important in defining aroma quality. Despite extensive studies, the metabolic regulation and sensory integration of these compounds remain incompletely understood. This review summarizes recent advances in the characterization of representative wine esters, including their aroma attributes, volatility, and concentration-dependent sensory effects. The contributions of several ester-producing non-Saccharomyces yeasts-such as Candida astrulatum, Torulaspora delbrueckii, Hanseniaspora uvarum, Metschnikowia pulcherrima, Pichia kluyveri, and Rhodotorula mucilaginosa-are highlighted, with emphasis on their roles in ester biosynthesis and the enhancement of wine aroma complexity. Particular attention is given to the biosynthetic and degradative pathways of acetate and ethyl esters, covering historical and current hypotheses, key enzymatic steps, and regulatory evidence. In addition, this review discusses the major routes of acetyl-coenzyme A (acetyl-CoA) biosynthesis in yeast and their relevance to ester formation. The functions and regulation of key aroma-related genes (ATF1, ATF2, EEB1, EHT1) are examined, alongside recent advances in metabolic engineering strategies, including promoter engineering, CRISPR-based tools, and strain optimization. The future directions include leveraging yeast biotechnology to enhance ester production and sensory complexity in wine, creating multifunctional wine that not only has unique flavors but also potential health benefits, and supporting innovation and diversity in the wine industry.