Under the Labeling Standards for the Manufacturing Process and Quality of Sake of the National Tax Agency Notice, brewer’s alcohol (or jozo-alcohol) is defined as alcohol distilled from fermented starch and sugar-containing substances. It also defines that the weight of brewer’s alcohol to be used for ginjo-shu and honjozo-shu must not exceed 10% of the weight of polished rice.
Brewer’s alcohol is approximately 95% content. Generally, Japanese sake makers lower its alcohol content to 30% prior to introduction into moromi mash. This is alcohol-added sake, or what we call aruten, Aruten used to present a negative image because one of aruten called sanzo-shu (literally three-time increased sake) was created during World War II at the time when there were shortages of rice. However, now it is required to pursue the ideal quality of sake.
The reasons for adding brewer’s alcohol are that it does not have much taste so that the taste of sake becomes refreshing and rather close to dry and creates a smooth and light finish. Also, the fragrant elements of sake dissolve well in alcohol rather than water, so it is considered to make the fragrance last longer or bring out more fragrance. Therefore, most of daiginjo-shu submitted for the annual sake awards seem to have a little amount of brewer’s alcohol. As the alcohol content gets higher, the risk of growth of harmful microbes like lactic acid bacterium gets lower.