The steam rises up from a freshly prepared bowl of ramen, a multitude of aromas along with it. Beyond the tantalizing smell, the sight of the dish itself is a work of art—complete with freshly cut scallions, an endless sea of noodles, a duo of soft-boiled eggs, and a dash of sesame for good measure. 

The only thing that’s missing? A warm cup of sake. 

The slightly sweet, nutty taste of this traditional Japanese beverage elevates just about any ramen dish, but it’s perfectly delicious as a standalone sipper, too. 

But what is sake made from? Read on to learn more about the complexities of this warming, one-of-a-kind libation. 

Sake: The Art of Perfecting a Simple Recipe 

What is sake made of? Believe it or not, this far-from-basic beverage consists of two simple ingredients: rice and water. Twenty percent rice and eighty percent water, to be exact.¹ Both of these ingredients are held to exacting standards in order to produce the highest-quality end result. 

Another fun fact? It’s brewed—not distilled. However, this isn’t your average beer-brewing approach. It’s an art form that the Japanese have developed over centuries. 

The required ingredients may be simple, but transmuting them is not. Let’s get into the nitty gritty of what makes sake, sake.

Seriously Nice Rice 

Sake making isn't your typical alcohol production and brewing process, and it start with rice. You wouldn’t make wine with just any garden-variety grape, right? Well, the same is true for Japanese sake. When it comes to making star-quality sake, the right rice for the job is shuzo-kotekimai, or “brewing rice.” 

This is a subcategory of rice that’s optimally structured for sake brewing. While there are many varieties within the subcategory, they all share one quality: a larger-than-average shimpaku (a starchy core) at the center of the grain.²

All types of rice have some form of starchy core beneath their outer layer of lipids and proteins. However, only shuzo-kotekimai varieties have a shimpaku that comprises 50-70% of the grain.

Before the Fermentation Process

Once sake breweries get their hands on the right rice, it then goes through quite a few processes before fermentation:¹

• Step 1 – First, the rice is harvested and polished. Nowadays, polishing is performed by a dedicated rice-polishing machine, though it can also be done by hand.

• Step 2 – Next, the rice is washed and soaked to remove the byproduct of polishing using cold water. Sake is traditionally made in the winter, meaning that washing rice can be an uncomfortably chilly job!

• Step 3 – Finally, the polished rice is steamed. Steaming cooks the rice, but keeps it firm. It prevents the grains from sticking to one another. As a general rule of thumb, more exposed surface area on the grain makes for better sake. This is because the process of sake brewing has a unique extra step that other fermented beverages lack. (More on that below.) 

Pure and Fresh Water

Water, known as mizu in Japanese, is essential to life. It’s also essential to sake brewing—so essential, in fact, that brewers use ten times more water than rice throughout the process of making sake. After all, it is the liquid component of the beverage.

A quality water source is a prerequisite for any sake brewery. Why? Simply put, high-quality water yields a high-quality taste. 

The quality of the water used during brewing has a major impact on the end product. For instance, a water source with iron levels that are safe for consumption might not be ideal for sake production. Even trace amounts of minerals can have a serious effect on the sake’s smell, taste, and appearance.

So, rice and water are the two main ingredients in sake. On the surface, it seems simple.  However, the process of brewing the sake is far more complex than meets the eye.

Sake Production 101

Put on your gloves and safety goggles—we’re doing science. To fully understand the production of sake, you’ll need to get a handle on a few rules of science—specifically, chemistry.

Rule number one: There’s no alcohol without the fermentation process. 

So how is this alcoholic beverage made? For those of us whose high schools didn’t offer “Home Brewing 101” as a class, here are a few more of the basics:

• Fermentation is an organic process. This is because yeast, the key ingredient in fermentation, is alive. More specifically, yeast are classified as single-celled microorganisms. 

• Yeast grows by metabolizing glucose. This process is known as “anaerobic respiration.” The waste products of this process are carbon dioxide and our ultimate brewing goal: ethanol alcohol.

• As fermentation continues, these byproducts begin to build up. As a brewer, alcohol production is what you’re aiming for. Unfortunately, some types of yeast will die in environments with less-than-optimal alcohol levels.³ The Brewing Society of Japan began supplying sake brewers with special strains of sake-brewing yeast in the early 1900s. This practice allowed for improved taste and aroma, and an average ABV of 14-16%.

Why Sake is in a League of Its Own

Wine is made with fermented grapes, beer with fermented barley, mead with fermented honey. Sake, as you know, is made with fermented rice. That means it’s different from all the rest.

You may have heard the drink referred to as “sake rice wine” or “Japanese rice wine,” but that moniker isn’t entirely accurate. Rice isn’t a fruit, after all. 

Sake can’t be lumped together with other grain-based alcohols either. It’s too dissimilar to beer and spirits in alcohol content and taste profile to be categorized alongside them.

What is the reason for this difference? The answer might surprise you.

Sake’s Secret Ingredient: Koji-Kin

The final piece of the puzzle, the part of the process that makes sake truly unique? Mold. 

Koji mold, to be exact.

Koji (Aspergillus oryzae) is the national fungus of Japan and it’s an essential ingredient in the production of many iconically Japanese foodstuffs (sake, miso, and soy sauce to name a few). It has an umami taste profile and brings a distinct savory, earthy flavor to the products it’s used to create.⁴

Starches and Enzymes and Glucose—Oh My!

Get those goggles back out. We need to cover a little more science before we can fully understand the impact Koji has on sake brewing. 

Here’s a rundown on how Koji contributes to the chemistry:⁴

Like yeast, mold is alive. Once Koji spores germinate, they release enzymes to begin metabolizing whatever they’re growing on.

• When growing on rice, Koji metabolizes starch, converting it into sugar in a process known as saccharification.

• Yeast can’t process starch—only sugar. Without Koji enzymes present to perform saccharification, there wouldn’t be enough natural sugar present to ferment. Yeast and Koji work together to achieve “multiple parallel fermentation.”

Alright, enough with the technical terms. Let’s get back to the practical stuff.

Where Toji and Koji Meet

Earlier we talked about how sake rice is steamed, rather than boiled, to keep the grains firm and encourage them to stay separate from one another. This frees up as much surface area as possible for the Koji spores to stick to.

Before the shuzo-kotekimai rice can be turned into sake: 

• It must be treated with a healthy coating of Koji spores. 

• After rice polishing and steaming, brewers lay the rice out on long tables covered with cloth. The toji (brew master) sprinkles the spores over the cooled rice.

• The rice is then mixed by hand, ensuring that the spores are evenly distributed. The process is repeated over the next two days until the mold has germinated and bloomed.

The Koji rice is combined with a fermentation starter, called shubo or moto, which means “source.” The starter is a lot like a sourdough bread starter. It contains:

• Koji-treated steamed rice
• Yeast
• Water 
• Lactic acid (to control bacterial growth). 

Once combined, these elements create the fermentation mash (moromi).

The moromi is added and tended to for approximately three weeks. Once the alcohol content has leveled off, the mixture looks a bit like a cumulus cloud. This fluffy mush is filtered and pressed. The resulting cake of fermented rice is called sake kasu, a popular ingredient in Japanese cuisine. The filtered sake is typically pasteurized and then stored to age.¹ 

The final step? Shipping it across Japan and around the world for alcohol enthusiasts to admire and enjoy. That's the art of creating this Japanese alcoholic beverage. 

But sake doesn’t alway have to be sipped on its own. Try mixing and creating sake cocktails with this one of a kind drink. 

DRNXMYTH: Toji-Approved Quality Cocktails

You found this article because you care about what goes into your drink of choice. Just like the master toji brewers, you’re a person who cares about quality. We get that—we’re the same way.

DRNXMYTH handcrafted cocktails are always fresh, never heated, and contain zero preservatives. They’re made by the people who know cocktails best—real bartenders. They even come in a unique double-chambered glass bottle, specially designed to deliver the highest-quality end result to you, an alcohol enthusiast with discerning taste. 

A focus on simple, fresh ingredients, exacting standards, craftsmanship, and passion is something we share with the sake brewers of Japan. 

So, let’s all lift our cups to quality. As they say in Japanese– kanpai! (Cheers!)

Sources: 

1. Japan’s National Research Institute of Brewing. The Story of Sake. https://www.nrib.go.jp/sake/story/pdf/SakeNo01_en.pdf
2. Sake Times. Shimpaku: Sake Times Glossary. https://en.sake-times.com/learn/shimpaku
3. Scitable by Nature Education. Yeast Fermentation and the Making of Beer and Wine. https://www.nature.com/scitable/topicpage/yeast-fermentation-and-the-making-of-beer-14372813
4. Nippon.com. Know Your “Nihonshu”: Understanding Sake Brewing. https://www.nippon.com/en/guide-to-japan/gu002002/
5. Sake Times.The Ingredient of Sake: Shuzo-Kotekimai. https://en.sake-times.com/learn/the-ingredient-of-sake-shuzokotekimai