Newcomer to Japan's national beverage? One of the first questions you'll have is: What is sake made of?
As with other fermented alcoholic beverages like beer or wine, sake can be brewed with minimal ingredients.
The essential sake ingredients are:
The quality of the individual ingredients in the sake brewing process will all play a big role in determining sake flavor profiles. Let's look at each.
At the heart of the best sake in the world is high-quality rice. The rice used in sake production isn't your typical table rice. (Let's save the Uncle Ben's for the chefs, not master sake brewers.)
The most common varieties of rice in sake brewing are short- and medium-grain japonica rice. Unlike regular long-grain rice, a japonica rice grain is plumper and denser. It's got a larger starch core, making it an ideal candidate for extensive rice polishing and fermentation. (More on that in a bit!)
Special sake rice comprises only 5% of the total rice production in Japan. Within the japonica family, there are also several premium sake-brewing rice varieties. These premium sake rice grains are called sakamai. They're found throughout Japan. Sakamai are used to brew the highest-quality Japanese sake including junmai ginjo and junmai daiginjo.
Among the most popular premium sake rice varieties are:
Of these premium rice grains, the most popular is Yamadanishiki. The variety took flight in Hyogo Prefecture in Kansai, a region encompassing Kyoto and Osaka. Today, Yamadanishiki is found in rice-growing regions throughout Japan. It's grown even as far north as Miyagi Prefecture, about 400 kilometres north of Tokyo!
Of course, it's not only the rice itself that's important for crafting all the different types of sake. How it's processed also makes a massive difference in the finished product.
Before entering into the brewing process, sake rice must be polished. The rice polishing process removes the outer layers of the rice grain. While the outer layers contain most of the rice's fiber, protein, vitamins, and minerals, they're not conducive to brewing great sakes.
At a minimum, the rice will have a polishing ratio of at least 75%. At this milling rate, 25% of the original size of the grain will have been removed. (Table rice, on the other hand, only polishes to 90 to 92%.)
To qualify as a ginjo, the rice polishing ratio drops to 60%; for daiginjo, it's 50% or less. In the highest-quality sake, brewers polish as low as 23%. There's little flavor improvement under 35%, though. Achieving it also raises production costs & time significantly.
Koji (Aspergillus Oryzae)
The most elusive & "exotic" ingredient in sake is koji. Known officially as aspergillus oryzae, koji is a mold that helps break down rice starch into sugars to prepare for fermentation. Without koji mold, sake wouldn't become, well, sake!
Master sake brewers (toji) take koji production (seigiku) seriously. Like all the other main sake ingredients, the quality of the koji affects sake flavor profiles strongly.
Producing koji starts with steamed rice. The rice is placed into a special room called a koji-muro and sprinkled with koji mold spores. After a couple days, you'll have a batch of koji rice to add to the batch.
High-quality rice and koji mold spores mean nothing without great water. It's no coincidence that many of Japan's best sake breweries are located close to mountains and springs. In fact, the water source is one of the main differentiating points popular sake brands use to market their products!
Water is used in two steps while brewing sake. It's first used during fermentation. Water is also added to undiluted sake to round out the flavor at the end of the brew.
The mineral content of the water has the most significant effect on the ultimate flavor of the sake. A high concentration of minerals like iron can add off flavors to the taste profile. Soft water, on the other hand, can create a more "boring" finish.
When used in the dilution stage, the water is often filtered to ensure the final sake taste is pure and odorless.
Much like in beer brewing, yeast is one of the main ingredients in sake. The type of sake yeast used can have a big effect on the flavor and the aroma of the brew.
The yeast is one of the most important additions to the brewing process. It's mixed with steamed rice and hot water, and koji to create a yeast starter (shubo).
Once a yeast colony forms in the shubo, it's added into a fermentation tank along with steamed rice, water, and koji rice to form a mash (moromi). The moromi is doubled in size three times over four days.
As the koji breaks down rice starch to sugar, the yeast converts them into alcohol and carbon dioxide. The fermentation process takes about 18 to 32 days.
Although not a required sake ingredient, brewer's alcohol deserves mention. During the fermentation stage, distilled alcohol is sometimes added to the moromi to round out the flavor. The extra alcohol creates a smooth and fragrant sake. Honjozo sake is a popular style of sake that adds in distilled alcohol.
Brewer's alcohol is distilled from various sources, including potatoes, corn, beets or sugar cane. It's only used in the production of honjozo and futsushu (a cheaper sake variety). Other Japanese sake varieties like junmai can't add alcohol to maintain their super premium labels.