Esters are compounds structured as if organic or inorganic acids and alcohol had lost a water molecule, and can also derive from amino acids. Neutral esters are usually aromatic, volatile liquids and those derived from alcohol and relatively short-chained fatty acids have particularly fruity scents. Esters exist only in tiny quantities in seishu, but their aromatic contribution is nonetheless considerable. Ethyl caproate has an apple-like aroma, and isoamyl acetate has banana aromatics, and the development in recent years of high-aroma-component-productive yeast has seen these two in particular become the primary components of contemporary ginjo-ka.
Other esters commonly occurring in sake include ethyl acetate, isobutyl acetate, ethyl butyrate, ethyl caprylate, ethyl caprate, ethyl laurate, phenylethyl acetate and ethyl lactate.