Relationship between medium-chain fatty acid contents and organoleptic properties of Japanese sake.

Medium-chain fatty acids (MCFAs) and ethyl esters are considered to contribute to some organoleptic properties, such as fatty odor and bitterness in Japanese sake. However, the relationships between these compounds and the organoleptic properties of sake remain unclear. Here, we quantified MCFAs and ethyl hexanoate in ginjo sake using gas chromatography with a flame ionization detector (GC-FID). The hexanoic acid concentration strongly correlated with fatty odor (p < 0.0001). The octanoic acid/hexanoic acid ratio correlated with butanoic acid concentration, which is likely correlated with inharmonious bitter taste. Multiple comparison analysis revealed that the ethyl hexanoate level was negatively correlated with bitterness. We then identified other chemical compounds correlating with fatty odor and bitterness using comprehensive two-dimensional GC coupled with time-of-flight mass spectrometry. By performing correlation analysis between certain compounds and sensory values following statistical selection for chemical compounds, we identified several candidate compounds correlating with fatty odor and bitterness in sake.