Effects of Kagoshima’s traditional Sake scientifically verified in study with Kagoshima University

Kurozake from Higashi Shuzo

It has been found that Kurozake, a type of cooking sake produced by Higashi Shuzo distillery using traditional methods, has effects of improving the color, texture, and aroma of Satsuma-age, fried fish cakes originating from Kagoshima. This finding was announced at a joint research presentation by the Faculty of Fisheries, Kagoshima University, and Higashi Shuzo on June 22.

Kurozake produced by the distillery is a type of Akumochi-zake whose production dates back to the Heian period (794–1185). This cooking sake, like regular sake, is made from rice brewed with Japanese koji-mold, but with the addition of lye, or aku in Japanese which is a strongly alkaline supernatant made from a mixture of wood ash and water, to enhance its shelf life. Since it is not heat-sterilized like regular sake, the enzymes are still active and rich in natural amino acids (umami) derived from rice.

In Kagoshima, Kurozake has been used for many years to make Satsuma-age, Toso (New Year’s herbal sake), and Sake-zushi (sushi made with sake), but there has been no clear functional analysis of its effects, and Higashi Shuzo has not been able to convey its benefits to the public. This prompted the distillery to start a joint research project with the Faculty of Fisheries, Kagoshima University.

In this study, the addition of Kurozake to the ingredients of Satsuma-age resulted in a darker fried color, a shinier cut-end, and a smoother texture on the tongue. The aroma of the Satsuma-age before eating and when putting it in the mouth was improved by almost double compared to the case of those without Kurozake. The fish smell was also reduced.

Nakada Masanobu, who was in charge of the research at the distillery, said, “The university’s academic re-evaluation of our product has given us a good opportunity to market our product based on its intrinsic value, rather than just promoting it based on the traditional and cultural value. We will confidently promote our Kurozake so that more people can get to know about it.” On the distillery’s website and Instagram, visitors can find many recipes that use Kurozake.