BCG medium (culture medium for detecting acid-producing bacteria)

BCG medium is a culture medium that plays an important role in sake brewing. It is used mainly to detect the presence of acid-producing bacteria in the moromi (fermentation mash). The medium is prepared under conditions that encourage the growth of microorganisms, particularly those originating from koji and shubo (yeast starter), and it helps with microbial control to maintain a healthy fermentation environment. Acid-producing bacteria can affect the flavor of sake by generating too much acid during fermentation, so using BCG medium to confirm and eliminate these microorganisms contributes to the production of high-quality sake.