Understanding Sake Off-Flavors: The Role of Pyruvic Acid and How They Develop

Sake off-flavors refer to unpleasant aromas and tastes that deviate from the sake's intended and inherent flavor profile. Unlike desirable ginjo aromas, these off-flavors can significantly detract from the sake's quality. They can emerge at various stages, influenced by both the brewing process and storage conditions.

Common Sake Off-Flavors and Pyruvic Acid

A variety of off-flavors are known in sake, including *hineka* (old sake aroma), *nikko-shu* (sunlight-exposed aroma), *nama-hineka* (raw old sake aroma), rubbery smell, and *hi-ochi-ka* (lactic acid bacteria spoilage aroma). For instance, *hineka* is an unpleasant aroma that develops during aging, while *nikko-shu* occurs when sake is exposed to ultraviolet light. Research has shown that specific components, such as pyruvic acid, a metabolic intermediate of yeast, are involved in the formation of these off-flavors.