Flavor mystery of Chinese traditional fermented baijiu: The great contribution of ester compounds

•A total of 510 ester compounds have been identified in traditional fermented baijiu.•Nine ethyl esters make important contributions to the baijiu flavor.•In the fermentation process of strong-aroma baijiu, 508 species have been identified.•Microbial fatty acid and amino acid metabolism contribute greatly to ester synthesis.•The metabolic processes of a minimum set of microbes help to stabilize baijiu flavor. Chinese traditional fermented baijiu is a famous alcoholic beverage with unique flavor. Despite its consumption for millennia, the flavor mystery behind baijiu is still unclear. Studies indicate that esters are the most important flavor substances, and bring health benefits. However, the aroma contribution and formation mechanism of esters still need to be clarified to reveal the flavor profile of baijiu. This review systematically summarizes all the 510 esters and finds 9 ethyl esters contribute greatly to the flavor of baijiu. The 508 different microbial species that have been identified affect the synthesis of esters through fatty acid and amino acid metabolism. The determination of minimum functional microbial groups and the analysis of their metabolic characteristics are crucial to reveal the mechanism of formation of baijiu flavor, and ensure the reproducible formation of flavor substances.