Saké Kasu Is a Well of Flavor, So Why Are We Throwing it Out?

Meet the brewing byproduct that adds depth to marinades, dressings, baked goods, and much more.

March 23, 2021
Photo by Hannah Kirshner

This excerpt has been adapted from Water, Wood & Wild Things by Hannah Kirshner, published by Viking, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright (C) 2021 by Hannah Kirshner.

One of the great pleasures of life in Yamanaka—a mountain town in Ishikawa, Japan—is eating saké kasu soft serve after a soak in the public hot spring. The local sake brewery, makers of Shishi no sato, sell the cones year round at their shop, just a block away from the baths. The ice cream’s refreshing and not-too-sweet flavor has all the floral yeasty aromas of saké without the alcoholic burn.

Saké kasu (or sake lees) is a byproduct of making saké. Saké is brewed from a mash of steamed rice, koji (steamed rice inoculated with Aspergillus oryzae), yeast, and water; kasu is the sediment left behind when brewed saké is squeezed out to be bottled or aged. Saké kasu is sold at Japanese markets in sheets, crumbles, or paste. But the best place to get it (if you can) is directly from a sakagura (saké brewery)—and there are more and more of them opening outside Japan.

Photo by Naofumi Miyajima
Photo by Hannah Kirshner

I began working at Yamanaka’s sakagura as research for my book—Water, Wood & Wild Things—and have continued to help there during the busy winter brewing season. One of my jobs is peeling kasu from the press after the saké runs off clear. The kasu comes off in big sheets, thick as a wool blanket, that are then cut and packaged to sell. Scraps and broken pieces are collected in a barrel, and we stomp on this kasu (with a specially designated pair of clean boots) until it ferments and loosens into a soft paste.

My boss, Matsuura-san, often sends me home with bags of saké kasu to use for cooking. On especially cold days I make amazake, mixing a little kasu with water for a thick hot-chocolate consistency, and warming it with a little sugar and grated ginger. I stir saké kasu into miso soup and use it to flavor sweets like pound cake. I mix it with miso to gently cure jammy eggs (Sonoko Sakai uses a similar blend to marinate mahi mahi).

There are sweet-and-salty mahogany brown pickles called nara-zuke made with kasu, and Namiko Hirasawa Chen shares a recipe for lightly pickled kasu-zuke cucumbers). Elizabeth Andoh suggests using kasu to make salmon chowder as many home cooks do in Tohoku. In Fukui, sweet saké kasu manju are sold as souvenirs. And Kato Sake Works in Brooklyn uses their saké kasu in all kinds of cooking experiments and collaborations, including panna cotta and okonomiyaki.

I’m often told by saké brewers that all the enzymes and yeast in saké kasu—that helped turn rice and water into saké—are also miraculously good for your health and beauty (there are myraid kasu-based skin products). I’m optimistic but skeptical about those promises—what I know for sure is that the flavor of saké kasu adds delightful complexity to sweets, marinades, and soups.

If you purchase sheets or crumbles (most common in the United States), make a paste so it’s easy to work with: smash it with a fork, adding saké or water as needed until the paste is the consistency of miso. Store it in a glass jar; leaving it loosely covered at room temperature for a day or two will help the paste soften and integrate. After that, keep the paste refrigerated with the lid sealed and use it within three months. Saké kasu will continue to ferment in your refrigerator (it may never spoil, but the color and flavor will change), but can keep almost indefinitely in the freezer.

And if you want to recreate that saké kasu ice cream (take a warm bath before you eat it and imagine you’re in a Japanese hot spring town), I have a recipe for you.

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Hannah Kirshner is author of Water, Wood, and Wild Things.  She is a writer, artist, and food stylist whose work has appeared in The New York Times, Vogue, Saveur, Taste, Food52, Roads & Kingdoms, and Atlas Obscura, among others. Trained at the Rhode Island School of Design, Kirshner grew up on a small farm outside Seattle and divides her time between Brooklyn and rural Japan.

1 Comment

Shala September 19, 2021
Hi ! just have a question . where would I find saké kasu ? I love on the east coast. is there anyway I could order it online ?