Koji is a mold used to make sake, shochu, soy sauce, mirin, and miso. Koji is the word for the mold spore itself, as well as the end product of koji mold spores grown on starch (for sake-making, that starch is rice). In sake-making, koji breaks down the rice starch into enzymes for saccharification (the process of making glucose). Then, the added yeast is able to ferment the glucose into alcohol. The vast majority of sake uses ki (yellow) koji, or aspergillus oryzae. But there are other types of koji that exist that sake brewers are beginning to use.
This month we explore sakes that use kuro (black), shiro (white), and ki (yellow) koji during production. Kuro koji, or aspergillus awamori, is most commonly used in making awamori and shochu. This koji is known for its full-bodied and rich flavor. True to its name, its color is a deep obsidian black. Shiro koji, or aspergillus kawachii, is a mutant form of black koji, and shares some characteristics with it – namely a pronounced citric acidity. Shiro koji is used often in shochu production. Ki koji, or aspergillus oryzae, is most often used for sake production, and is also used in soy sauce, miso, and shochu production. Ki koji is known for its mild fruit aroma, and refreshing, clear taste. Despite its name, ki koji is more green in color than yellow.
I started noticing more sakes using different types of koji last year. So I began to wonder, why use different types of koji in sake? When asking the brewers about this month’s sakes, their motivations varied. Different kojis are used for brewing sake for unique flavor, food pairing possibilities, and fermentation techniques. Ikegame-san of Ikegame Shuzo wanted to make a sake that would pair well with non-Japanese flavors like cheese and roasted meats. Takahashi-san of Hachinohe Shuzo said that they wanted to use a simpler fermentation technique called kō-on tōka (high temperature saccharification fermentation), which is possible with slower growing white and black kojis. “Making shubo is simplified during this process because there is no need to add lactic acid,” Takahashi says. While Nakamura-san of Kiuchi Brewery wanted to make a sake very high in amino acid for a strong umami taste, and therefore used all koji-inoculated rice during the brewing process.
My scavenger hunt to track down all four bottles under this one theme started last summer, and I am so happy all bottles are here in time (the pandemic has made delivery from Japan very unpredictable). Please notice that apart from the aged Kiuchi Kikusakari Zen Koji, all three bottles have very fresh bottling dates!
Co-Founder + Sake Director
LEVEL 1: Introductory Membership (Two 300ml bottles)
Mutsu Hassen Tokubetsu Junmai
Hachinohe Shuzo (Aomori, Japan)
Seimaibuai: Hanafubuki 60%, SMV: +1.3, Koji: White
Hachinohe Shuzo is well-known for their use of the kō-on tōka (high temperature saccharification fermentation) method in conjunction and use of white koji for all of their sakes. White koji grows slower than yellow koji, and one way to propell fermentation is to ferment at a higher temperature. Kō-on tōka results in sakes high in citric acid for a crisp, fresh taste. Because this process creates citric acid, lactic acid (which is usually added to yellow koji moromi) is not added during fermentation. This sake has a delicate nose of cherries and cream, and has a pleasant lime flavor. The sake ends dry and snappy which complements salty flavors like ikura and citrusy flavors like crab with a squeeze of lemon. Enjoy this sake chilled or warm.
Kiuchi Brewery (Ibaraki, Japan)
Seimaibuai: Hitachinishiki 55%, SMV: -18, Koji: Yellow
During regular sake-making, only a fraction of the steamed rice used for fermentation is innoculated with koji mold. However, for this sake, all of the rice has been innoculated with yellow koji. This accelerates the speed and intensity of the saccharifcation process, resulting in a sake very high in amino acid (umami). A high amount of amino acid coupled with the fact that this sake has been aged for 5 years, yields a bold and luscious sake with aromas of raisin and soy sauce, and flavors of prune, sherry, and nuts. Try out these blissful food pairings: Zen Kouji at room temperature with duck salame or pate. If you have a sweet tooth, try this sake with Maya Mountain 85% Dandelion Chocolate.
LEVEL 2: Premium Membership (Two 720ml bottles)
Kuro Kabuto Muroka Junmai Daiginjo
Ikekame Shuzo (Fukuoka, Japan)
Seimaibuai: Yamada Nishiki 50%, SMV: -2, Koji: Black
Ikekame Shuzo distills shochu in addition to sake, so they are no strangers to all types of koji. The main motivation for brewing sake with black koji was to create a sake that would pair well with non-Japanese flavors like cheese and roasted meats. When using black koji, the kō-on tōka method is also utilized (see Mutsu Hassen). Like white koji, this results in a sake with high citric acid. While aromas of mango, banana, and passion fruit will delight the daiginjo fan, this sake also offers an unexpected sweet and tart complexity thanks to the citric acid resulting from the use of black koji. Enjoy this sake chilled alongside seafood escabeche, duck pate, or a fragrant muenster.
Tsuchida Kimoto Junmai Ginjo 2019-2020
Tsuchida Sake Brewery (Gunma, Japan)
Seimaibuai: Asami no Yume 60%, SMV: -4, Koji: Yellow
Tsuchida Brewery is known for its kimoto sakes (fermented using naturally occuring lactic acids). For their Kimoto Junmai Ginjo, they use an old gene of yellow koji that turns sake kasu (lees) black, typically used for shochu. This gene is very robust, so they set the temperature during fermentation at a lower temperature than usual. The enhanced lactic acid in this sake lend aromas of warm milk and roasted hazelnuts. Enjoy an array of flavors, from yogurt to green grapes. These bright yet earthy flavors were a delicous complement to kanimiso (crab tomalley), or with caviar (sturgeon or vegan tonburi). Try chilled or warm.