Four Core Ingredients of Sake

Pure saké, also known as junmai saké, contains just four ingredients: Rice, Water, Koji and Yeast.

The fact that a great deal of saké is made from just four ingredients can come as quite a shock. How can a nigori style have distinct flavors of cherry, coconut or honey? And why do I detect floral and melon notes on the nose of my daiginjo? The answers generally boil down to two factors: 1) A master brewer's selection of each type of ingredient and 2) The brewing techniques they deploy to achieve their vision. Below we'll shed some light on how each of the four ingredients can impact the taste, aroma and quality of any given saké.


RICE

Generally there are two types of Asian rice: Indica, which is long-grained, and Japonica, which is short-grained. Japanese saké is brewed using varieties of Japonica, specifically varieties that are bred to be non-sticky. Due to their less complex molecular structure, the koji enzyme can convert the starch to sugar much more efficiently.

So, desirable saké rice is short-grained and non-sticky when cooked.

When crafting a premium saké, the brew master will look into additional quality-yielding factors.

  • Low protein content which conversely means a high proportion of desirable starch.
  • A large "shinpaku" or pure starch component found at the core of each grain. Flat and disc-shaped is ideal.
  • Large grains weighing between 25 to 30 grams per 1,000 grains mean undesirable components can be removed thoroughly.
  • Resistant to cracking during milling/polishing. Cracks and breaks lead to in-efficient starch to sugar conversion.
  • High solubility and absorbency during the brewing phase means water can penetrate to the core of the grain during washing, soaking and steaming and creates an ideal vessel during fermentation.

Here are a few of the most common saké rice varieties:

Yamada-Nishiki - Hyogo Prefecture
Known as the "king" of saké rice, Yamada-Nishiki has been around nearly 90 years. Huge grains and large, well-defined shinpaku make it the perfect choice for ultra-premium and highly polished ginjo and dainjo styles. Saké brewed with Yamada-Nishiki tend to have delicate aromas and crisp clean fruit and floral flavors.

Gohyakuman-goku - Niigata Prefecture and West Coast Japan
Despite a slightly smaller grain, Gohyakuman-goku rice is similarly well-suited for polishing like Yamada-Nishiki and is particularly ideal for making koji. Also similar to Yamada-Nishiki, this saké rice is often used to produce delicate saké with simple, light and dry flavors, aromas and finishes.

Fun Fact: Over fifty percent of saké is brewed using one of the above rice varieties.

Miyama-nishiki - Nagano Prefecture and Mountains in northeast Japan
Smaller grains similar to Gohyakuman-goku, Miyama-nishiki rice is adapted to growing in mountainous conditions and often yield rich and robust saké. Enhanced sweetness and bigger flavor than its Yamada-nishiki counterpart, Miyama-nishiki saké tends to keep its flavorful identity hidden behind muted aromas.

Fun Fact: Saké-specific rice is a registered designation.

Dewa-sansan - Yamagata Prefecture
An emergent specialty of the region and relatively recently registered as a saké-specific rice in 1997, Dewa-sansan continues its rise in popularity through junmai ginjo batches seeking the distinction of 'Dewa33.' Those saké that achieve the Dewa33 designation are known for their purity, depth and unique hints of herbal aromas.

Omachi - Okayama Prefecture and neighboring prefectures.
One of the oldest saké-specific rice varities, Omachi rivals Yamada-nishiki in both grain and shinpaku size. The biggest difference is the shape (fat rather than disc-like) and its soft shinpaku. Consequently, this makes Omachi a poor choice for premium polishing rates which results in a greater retention of fats and proteins. As such, Omachi saké is commonly designed with earthy flavors and buttery textures in mind. Like most umami saké, Omachi is often recommended served warm.

As you can already see, when a product as complex as saké uses only four ingredients, the selection of the specific ingredient such as the variety of rice grain has an overwhelming impact. To further compound the point, it is also possible for brewers to use different varieties of rice within a single batch, sometimes identifying a grain for koji and a grain for steamed rice that is to be added during the main fermentation build.


WATER

From a utility standpoint, as long as the water is clean it is generally suitable for brewing saké. 

However, in premium saké, water composition matters a great deal which is why seasoned saké drinkers can often connect flavor characteristics to unique regions. Similar to beer, saké is brewed where the quality water is rather than where the grain or other ingredients are cultivated. Also similar to beer, water makes up over 80% of the final product. So, it is important.

While minerals like magnesium, potassium and calcium can be debated in terms of desirability, iron is universally considered undesirable. Depending on the style of sake, the mineral levels or 'hardness' can create varying levels of bitter/dryness or fruity/floral ginjo style flavors.

Saké breweries in soft-water havens such as Kyoto and Hiroshima do very well producing contemporary, gentler and more fragrant styles of saké such as junmai ginjo and daiginjo while breweries in mineral rich areas such as Kobe continue creating and iterating upon striking traditional styles. 

When enjoying your saké, take a moment to note of where it was brewed so you have yet another tool in your toolbox that will help guide you to a new favorite. 

Fun Fact: Many large breweries possess the ability and technology to filter elements out or add elements in to their batch water, giving the brewery an added dimension of versatility when brewing styles that would otherwise be difficult using regionally sourced water as-is.


KOJI

Koji-kin (aspergillus oryzae) is a type of mold that is the foundation for many Asian food products such as miso, soy sauce, mirin and of course, saké. 

Rice becomes 'koji' when it has been steamed and inoculated with koji-kin. It's purpose is to deliver enzymes that convert the rice starch into fermentable sugar. However, the influence of koji goes beyond being a fermentation buddy to the yeast. Depending on the strain and type of koji-kin, varied levels of vitamins, amino acids, citric acid and other factors can affect both aroma and flavor.

Nearly all saké use Yellow strain koji as this particular strain limits acidity and promotes a smooth mouthfeel and light sweetness due to its inability to convert all starch into sugar. 

By now you likely understand that there are two general and diametrically opposite styles of saké; umami stylé, which is bigger in body, acidity and may feature intense earthy flavors, and ginjo style, which is light bodied, fruity and/or floral. So, it should come as no surprise that the two types of yellow strain koji residing at each end of the spectrum help deliver either umami or ginjo characteristics. 

So-haze

Brewers who select the 'so-haze' type of koji-kin often times are looking to produce a table-grade futsu-shu saké or a full bodied, high acidity and umami-rich premium style. It is the high vitamin, protein and organic acid content that creates these qualities.

Tsuki-haze

The lighter mold growth pattern of 'tsuki-haze' (pronounced skee-hah-zay) means a slow and very controlled fermentation, ideal for brewing the delicate, crisp and fruity/floral ginjo and daiginjo style saké.

Refer to Step 3 of the sake brewing process for insight into how koji is cultivated.


YEAST

The fourth and final critical component to saké brewing is yeast. Saké yeast strains are resilient, continuing to create alcohol beyond the point when many other brewing yeasts become dormant. This is why the alcohol content or ABV of saké can reach upwards of 20-22% during the fermentation stage. 

Not only is yeast a necessity when it comes to converting the sugars created by the koji into alcohol, but its impact on flavor, aroma, texture and acidity levels in the final product also cannot be understated or ignored. Brewers take great care in selecting the ideal yeast strains for their styles.

For modern brewers, the task of identifying the right yeast has become much easier as entities like the Brewing Society of Japan meticulously breed and catalog a multitude of saké yeast strains, creating a trusted source for brew masters around the world. This is important as yeast is a living organism and will mutate or adapt, inherently changing the ways it will influence a given batch. Similar to the rice, water and koji ingredients, yeast strains come in a variety and they can be mixed and matched to create many different expressions.

Let's look at some of the staples of saké yeast and how they impact saké.

Brewing Society yeast is cataloged numerically. 

Numbers 1 through 8

Identified for their ability to produce a complete and successful fermentation meant these yeast strains presented a lower risk option for brewers in the early-to-middle 1900s. The strong ferments of these yeast generally create saké with higher acidity and subtle aromas. 

Of the original eight strains, numbers 6 and 7 are still prominently used. Number 7 is particularly noted for its pleasant and subtle sweet and fruity aromas, making it the standard for many futsu-shu saké and fairly prevalent in honjozo and junmai styles as well.

Numbers 9 and 10

Moving past the initial pursuit of yeast that facilitated a complete fermentation, numbers 9 and 10 successfully brought forward the fruity and floral aromas that have become standards for the ginjo and daiginjo styles. 

Numbers 14 and 18

Over the past forty years, the desire and efforts to push aromatic boundaries set by #9 and #10 have only intensified, yielding a new modern age of delicate, promising and smooth saké. 

In many cases, saké created using #14 and #18 forego acidity in favor of pronounced fruity and floral aromas and flavor. These qualities are punctuated by a delicate and juicy texture, especially when served chilled. One of the biggest challenges for brew masters using these strains is to not disappoint the consumer with mismatched flavor to the beautiful aromas.

These are the main yeast strains used in today's saké. As you can imagine, a deeper layer of complexity exists within this ingredient category as some brewers invest their resources to create proprietary yeasts and yeast blends to give their products a true one-of-a-kind quality.