Ester
Japanese: エステル
Aromatic compounds formed when organic acids combine with alcohols. Produced by yeast during fermentation, they create fruity, floral aromas.
Esters are compounds formed when organic acids combine with alcohols through dehydration condensation. Many fruit aromas derive from esters—isoamyl acetate (banana), ethyl acetate (apple) being prime examples.
The floral, fruity fragrance of sake and wine comes from esters produced by yeast during alcoholic fermentation. The type and amount of esters vary with yeast strain, temperature, and nutrient conditions, defining each beverage's character.
Esters also exist in miso. During aging, trace amounts of alcohol and organic acids meet, adding subtle fragrance. An inconspicuous presence, yet the source of that 'pleasantly good aroma' is often these esters.