What is Junmai Sake – Beginner’s Guide to Japan’s Ancient Drink

Sake is gaining in popularity outside of Japan, so now is a better time than ever to say hello to this fascinating drink. Yet, with so much variety and lack of widespread knowledge, it can be hard to know where to start. 

Sake is an interesting drink in that its brewing process is more akin to that of beer, but its flavor profile is closer to that of wine.

Today we’re starting with Junmai, one of the fastest-growing styles and one of a somewhat “premium” category.

Junmai sake is made from just four ingredients: rice, water, yeast, and koji mold. The category depicts a move to top-notch sakes that are crafted for perfection. It’s similar in concept to the German purity law for beer-making—the Reinheitsgebot—which allows nothing but malted barley, hops, and water. 

Junmai means “pure rice” in Japanese. It’s a name that reflects the meticulous care and quality of the sake. Unless a bottle says “Junmai” (written in Japanese as 純米), it will most likely have added brewer’s alcohol. Which isn’t a bad thing in itself! However, you should keep an eye on other additives like sugar, artificial flavorings, among a range of further cost-cutting, hangover-inducing nasties.

Bear in mind, though, that just because sake isn’t Junmai, that doesn’t mean it’s inferior. Skilled brewers use additives like brewer’s alcohol to enhance flavor profiles and aromas, making smooth and easy-drinking sake. The idea that “real” sake drinkers only drink Junmai would be a misconception. Not everyone prefers authentic junmai, nor does it imply that everything else is subpar.

How is Junmai sake made?

Before the actual sake-making process, one of the first things you have to do is “polish” the rice by milling it—removing each grain’s outer layer and exposing its starchy core.

When making Junmai sake, you mill the rice to “Seimai Buai,” or 70%. It means you need to get rid of nearly a third of each grain by removing a portion of its surface. This removes excess starch and impurities, improving the final quality of the drink.

How much rice has been polished usually suggests a higher classification level. However, more polishing doesn’t always make rice better. Some experts prefer more affordable, local stuff—provided it’s made of quality ingredients.

Milled rice is washed and steamed. It’s then mixed with yeast and koji and left to ferment. Over a few days, more of the three main ingredients (except yeast) are added in several batches. This ferment, called shikomi, usually happens in huge tanks. Many factors like rice quality, koji mold growth, and the temperature are different for each shikomi. The ferment is left from 18 to 32 days. Afterwards, you need to press, filter, and blend it, but not always.

It’s hard to reduce the rest of the process down to the summary below, but for the sake (pun intended!) of an easy-to-digest introduction to sake, the process goes as follows:

• The rice grains are milled.
• Rice is washed to clean the Nuka (white starchy residue).
• The grains are soaked in a predetermined quantity of water.
• They are steamed in a vat called a Koshiki.
• Steamed rice is typically separated—some getting inoculated with Koji mold and some going straight to the fermentation vessel.
• Koji Making (Seigiku)—The Koji ferment is monitored for 36 to 45 hours in a room with higher-than-normal humidity and temperature.
• Yeast starter (Shubo or Moto)—made by mixing koji and the rice from the above two steps, water, and a concentration of yeast cells.
• The mash (Moromi)—After moving to a larger tank, you will add more rice, koji, and water in several stages over four days, roughly doubling the batch’s size each time.
• Over the next 18 to 32 days, this mash ferments and its temperature—among other factors—are measured and adjusted according to the desired flavor profile.
• Pressing (Joso)—at this stage, the white lees (kasu) and unfermented solids are pressed away, letting clear sake runoff.
• Filtration (Roka)—the sake sits for a few more days to allow more solids to settle out before filtering it through charcoal.
• Pasteurization—most sake (minus namasake) is then pasteurized once. 
• Aging—finally, the sake ages for about six months, helping to round out the flavor before shipping. The aged sake is then cut from 20% to roughly 16% with filtered water.

While the fuller body and heavier flavor profile of Junmai may be a little intimidating for some sake beginners, the effort and craftsmanship behind the style make it a genuinely unmissable drink. It makes its presence known assertively, and you’ll enjoy its slightly higher acidity paired perfectly with food.

What is Junmai Sake? F.A.Q.

Do you serve Junmai warm or chilled?

You’d typically serve Junmai-style sake warm, except for Junmai Ginjo and Junmai Daiginjo styles—which are best served chilled to preserve the delicate aromas and flavor. Chilled sake is becoming increasingly popular, and many styles are produced explicitly on the premise that you’ll drink them chilled.

However, you should be careful when chilling sake. Don’t overdo it, as it can mask the flavor profile and affect the drink’s integrity.

What food does it pair well with?

The best match is something similar, like a rice-based dish with heavy seasoning. It also goes well with red meat, pork belly, and fatty fish—think tuna and salmon.

What is koji mold?

Koji is steamed rice that has been inoculated with koji-kin (koji mold)—also known as Aspergillus oryzae. It is used in sake production to break down starch molecules into simple sugars that can be fermented by yeast.