Sake Kasu: A Guide to Using and Storing Sake Lees
Sake kasu (also called sake lees) is the solid residue left behind after sake is pressed. It turns up in soup, amazake, and pickling beds, prized for the savory depth it adds to a dish. Because it still carries alcohol, though, it's worth thinking about who you're serving it to and how it's cooked. This guide walks through the main types of sake kasu, how it's typically used, how to store it, and what to know about its alcohol content.
What Sake Kasu Is: The Solids Left Behind at Pressing
Sake kasu comes from joso (上槽), the pressing stage that separates fermented mash (moromi) into clear sake and solid residue. The technique of pressing itself is covered in a separate article on pressing (joso).
Sake kasu is essentially fermented rice and koji (mold-cultured rice) in solid form. Some of the sake's own components remain in it, so it retains a bit of alcohol as well. This byproduct concentrates the rice's natural umami and aroma, and cooks have long used it to add fermentation-driven richness to everything from soups to pickles.
Three Main Types of Sake Kasu
Sake kasu sold commercially falls into three categories: itakasu (flat sheets), barakasu (loose crumbles), and nerikasu (aged paste). All three come from the same base material. They differ in shape and how long they've been aged.
Itakasu ("board lees") comes out flat and sheet-like, the shape it takes when pressed by an automatic press and cut into pieces. It's firm and slow to dissolve, so soaking it in water or sake for a while before cooking makes it much easier to work with.
Barakasu ("loose lees") refers to sake kasu that comes out crumbled rather than in sheets. The only difference from itakasu is shape. The flavor is the same. Because it's moister and softer, it works well in dishes like soup or amazake where you want it to dissolve.
Supermarkets typically stock itakasu and barakasu, and even if what you buy has crumbled apart, the composition is unchanged, so you can use it the same way.
Nerikasu ("kneaded lees") is sake kasu that has been aged until it turns into a soft paste. It's closely related to fumikomikasu ("trodden lees"), made by packing sake kasu into a tank to age, though the exact distinction varies by brewery and region. Left to age for several months with the air pressed out, it mellows into a rounder flavor. A pale pink color is considered a mark of quality, and it has long been used as the pickling bed for dishes like Nara-zuke pickles.
| Type | Shape / state | Best used for |
|---|---|---|
| Itakasu (board lees) | Flat, firm sheets; slow to dissolve | Soaking before use in soup or pickling beds |
| Barakasu (loose lees) | Crumbled, soft | Dishes where it needs to dissolve, like amazake or soup |
| Nerikasu / fumikomikasu (aged paste) | Aged into a soft paste | Pickling beds, such as for Nara-zuke |
Four Classic Ways to Use Sake Kasu
The four standard uses for sake kasu are kasujiru (sake-lees soup), amazake, kasuzuke (lees-pickling), and as a background flavoring. Whether you dissolve it, pickle with it, or stir in just a touch depends on what you're making.
Kasujiru is a soup made by dissolving sake kasu into miso soup or pork soup (tonjiru). Paired with salmon, daikon radish, or root vegetables, it adds richness and a warming quality. When using itakasu, thin it first in a bit of the cooking broth before adding it to the pot, so it doesn't leave undissolved lumps.
Kasuzuke is a pickling method built around a sake-kasu bed for fish, meat, or vegetables. Mix about 100g of sake kasu with roughly 50ml of shochu or mirin to make a paste, and you have a pickling bed you can put together at home. Either shochu or mirin works on its own. You don't need both. A fish fillet left in the bed for half a day to a full day firms up nicely and takes on extra flavor.
Amazake is a drink made by dissolving sake kasu in hot water and sweetening it with sugar. A rough guide is about 50g of sake kasu dissolved in 200ml of hot water, sweetened with one to two tablespoons of sugar. It's long been a winter favorite. Amazake actually comes in two distinct forms, though, which is worth sorting out. More on that in the next section.
Sake kasu also works as a background flavoring. Add about a teaspoon to stews, gratins, or other simmered dishes besides kasujiru, and it deepens the flavor. Add too much and the aroma of the sake kasu becomes overpowering, so start with a small amount and adjust from there.
Amazake Comes in Two Forms: Sake-Kasu and Rice-Koji
Amazake comes in two forms: one made from sake kasu, the other from rice koji. They share a name, but differ in both ingredients and alcohol content. Mixing the two up matters, since serving the wrong one to someone who can't have alcohol is a real risk.
Sake-kasu amazake is made by dissolving sake kasu in water and sweetening it with sugar. Because the sake kasu itself retains alcohol, this version contains a small but real amount. And it doesn't disappear entirely even after heating.
Rice-koji amazake is made by holding rice koji at around 55°C (131°F) for several hours, letting the koji's enzymes convert the rice's starch into sugar. It turns sweet without any added sugar and, in principle, contains no alcohol. That said, if home preparation gets the temperature wrong and it's left too long, wild yeast can take hold and produce a trace amount of alcohol.
| Type | How it's sweetened | Alcohol |
|---|---|---|
| Sake-kasu amazake | Sake kasu dissolved in water, sugar added | Contains alcohol (remains even after heating) |
| Rice-koji amazake | Koji enzymes convert rice starch to sugar | Alcohol-free |
If you're serving amazake to children, someone who's pregnant or breastfeeding, or anyone about to drive, choose the rice-koji version. Store-bought products list their ingredients, so you can check: if "sake kasu" appears on the label, that amazake contains alcohol.
Storage: Refrigerate as a Rule, Freeze for the Long Term
Sake kasu should be refrigerated as a rule. It will keep at room temperature for a while, but chilling it slows changes in color and flavor. Once opened, wrap it tightly to keep out air and store it in the refrigerator.
For longer storage, freezing works well: it keeps for about a year in the freezer, and you simply thaw it naturally before use. If it's hardened, soaking it in a bit of sake will restore its original softness.
Sake kasu darkens and mellows in aroma the longer it's kept. This aging process is exactly what produces nerikasu. That color change on its own isn't necessarily spoilage, but discard any batch that develops mold or an off smell.
Alcohol Content: Know Who Shouldn't Have It
Sake kasu contains alcohol. Itakasu runs at roughly 8% alcohol by volume, comparable to a canned chu-hi (a Japanese canned cocktail, typically around 3–9% ABV). Don't assume that because it's a pressing byproduct, the alcohol is negligible.
Heating reduces the alcohol content but doesn't eliminate it entirely. Experiments have found that even high-heat cooking leaves a small residual amount. Even in a well-simmered dish like kasujiru, it's safest to assume some alcohol remains.
Take particular care with the following:
- Anyone under the legal drinking age
- Anyone who is pregnant or breastfeeding
- Anyone planning to drive a car or ride a bicycle
- Anyone with low alcohol tolerance
If you're serving any of these people, the safest choice is to switch to rice-koji amazake made without sake kasu, or to skip sake-kasu dishes altogether.
Sake kasu is a byproduct of pressing, yet it broadens what's on the table: from soups to pickles to amazake. Once you understand the types, the ways to use it, and the alcohol considerations, you can work it into your cooking comfortably all year round.
- This article is intended for readers of legal drinking age (20 in Japan). Please drink responsibly. Avoid alcohol during pregnancy or breastfeeding, and never drink and drive.