Culture Corner
Sake - Part 3 - The Basic Ingredients
In this installment of our discussions on Sake, we will discuss the basic ingredients of Sake, the different kinds of ingredients and how they affect the final result. These ingredients include:
Rice
Rice has always been a staple part of the Japanese diet. Up until roughly 50 years ago, rice was in short supply, with production volumes unable to meet domestic demand. Thus, the rice available for sake brewing was understandably limited, and brewing itself was confined to the winter months, when lower temperatures and cleaner winter air provided the best conditions for brewing and storage (natural refrigeration helped keep sake fresh for consumption months after it was brewed). Such conditions made large-scale brewing unfeasible until recent times, and resulted in regional sake brands that closely matched the local climate, cuisine, and tastes of the local population. These fairly distinct regional styles can still be identified today.
Sakamai or Rice Variety
There are several types of rice used to make Japanese sake, and each type yields specific flavor profiles. Keep in mind that these nine types of rice are only part of the battle. How sake is brewed and the water used are the other parts of the story. Further, there is a massive range of styles and tremendous overlap across the board. Finally, the degree of rice milling plays a major role in the final product.
Yamada Nishiki Rice
From Hyogo, Okayama and Fukuoka. The so-called King of Sake Rice. Typically produces a fragrant, well-blended soft flavor.
Omachi Rice
From Okayama. Generally less fragrant, more defined flavor elements, with more earthiness. The only pure strain of rice left in Japan.
Miyama Nishiki Rice
From Iwate, Akita, Yamagata, Miyagi, Fukushima, and Nagano. Produces a slightly less dry sake, with a more rice-like flavor.
Gohyakumangoku Rice
From Niigata, Fukushima, Toyama, and Ishikawa. Smooth, clean, dry and slightly fragrant.
Oseto Rice
From Kagawa. Rich and earthy, very distinctive.
Hatta Nishiki Rice
From Hiroshima. Earthy undertones, usually in the background. Rich flavor, quite nose.
Tamazakae Rice
From Tottori and Shiga. Soft and deep, with complex background activity when brewed right.
Kame no O Rice
From Niigata and Yamagata. Rich and flavorful and a bit drier and more acidic than other rice types.
Dewa San San Rice
From Yamagata and Niigata. Complex, not so dry, midly fragrant.
Water
Sake is, at first glance, a simple creation. The main ingredients are water, rice, koji, and yeast. Pristine and uncomplicated. But things get a bit more involved just beneath the surface. Water is an appropriate analogy of the apparently simple yet inherently complex nature of sake brewing.
The Role of Water
Sake in its completed form is about 80% pure water. Before it arrives at that final stage, however, it is exposed to large amounts of water in each step of the brewing process. The rice is washed, rinsed, and soaked before it ever gets close to the steaming process. Water is then added to the fermenting moromi in the tanks at each of the (typically) three "shikomi," or additions of rice, water and koji. Finally, a little water is almost always added at the end to bring the alcohol down from the naturally occurring twenty percent or so to around sixteen percent.
All together, the amount of water that goes into a bottle of sake adds up to be more than 30 times the weight of the rice used. It therefore deserves a bit of attention.
Sake Watering Holes
Most of the traditional sake brewing locations, like Nada (Kobe), Fushimi (Kyoto), Saijo (Hiroshima) and Aizu-Wakamatsu (Fukushima) came into existence partly due to the abundant supply of good water in the region. There was no chemical analysis available in the 1700's, but the final product told the story, and everyone rushed to set up shop where success had been proven.
The most famous example of this is the water that rushes down from Mt. Rokko in Hyogo Prefecture into Nishinomiya and Nada. Known as "Miyamizu," sake made using this water was immensely popular among the elite. This led to the region having more breweries and producing more sake than any other place in Japan, a statistic which still holds true today.
Eventually science caught up to intuition and experience and found ways to determine what exactly makes "good water" for sake brewing, as well as what does not. The results of extensive research by sake-brewing research centers, which exist in almost every prefecture, have now become common knowledge to brewers.
What's Good, What's Bad, What's Ugly
There are a number of elements whose presence is indispensable, without which certain steps of the brewing process will not proceed smoothly. There are also several things that are only detrimental, and either impede the process or adversely affect the sake in other ways.
The Good
There are a number of elements and compounds whose presence is indispensable. In particular, potassium, magnesium and phosphoric acid are necessary to aid the propagation of the yeast in the "shubo" (yeast starter), as well as in the proper development of good "koji". If these are not present in sufficient amounts the yeast cells will not multiply as well or as quickly, throwing off the timing off of the entire fermentation so that it cannot be properly controlled.
One of the problems is that potassium is water soluble, and can be washed away during the rice washing and soaking processes. Phosphoric acid is generally attached to fat and protein molecules. It must be removed from these, broken by enzymes from the koji, thereby freeing it up to be used by the yeast. This shows how integrated the various aspects of the brewing process are.
The Bad and the Ugly
The biggest problem is iron. Iron will darken the color of sake and adversely affect its taste and fragrance. Also, as sake ages, the residual sugars react with amino acids present to change the flavor and smell, and the presence of iron hastens this reaction.
Manganese plays a different but equally negative role. When sake is exposed to light, in particular ultraviolet light, manganese promotes a chemical reaction that will discolor and de-luster the appearance of sake. In direct sunlight, this change can be seen in less than three hours.
Where Do Brewers Get Their Water?
Forgetting everything else, where do sake breweries get their water? More of it comes from wells than any other source. The stable temperature of deep well water gives it consistency, although the individual qualities of a well vary with depth and the land.
Rivers flowing from the mountains as well as lakes and other bodies of water are also used, but the changes in the environment over the last century or so have rendered many of these useless, which is not to say this practice is completely obsolete. Many breweries brag about their region's "meisui" (famous water), insisting that it is one of the secrets of their fine brew.
Naturally, water can be chemically altered and synthetically produced to specifications, so many breweries take that route. Still others use local tap water, and filter it or alter it as is necessary to fit their needs.
As a general classification, water for brewing is often referred to as "kosui" (hard water) or "nansui" (soft water). Although both kinds of water have the potential to make good sake, the brewing methods are subtly different for each. The famous Miyamizu of Kobe is kosui, whereas nearby Fushimi water in Kyoto is nansui. Both Hiroshima and Fukushima have, in general, soft water.
Among sake brewers, water is more often referred to as "tsuyoi mizu" (strong water) and "yowai mizu" (weak water). This refers to how well the water promotes fermentation. And just because the water is "weak" does not by any stretch mean it is not suitable for brewing; it just indicates that the timing of certain steps will be different. Although the correlation is not completely direct, hard water is generally strong water.
Yeast
Importance of Yeast in Sake Brewing
The importance of yeast in the production of sake is extremely important, as yeast influences many elements of sake taste, most noticeably sake fragrance. And since our sense of taste is highly influenced by (if not dependent on) our sense of smell, this is crucially important.
What is Yeast? What Does it Do?
Yeast converts sugar to alcohol and carbon dioxide. It is the heart of the creation of all alcoholic beverages. But different yeast strains have different by-products, like esters, alcohols, and acids and other chemical compounds that affect the nuances of fragrance and flavor.
Each yeast will give rise to its own specific array of chemical compounds, with scary names like ethyln caproate and isamyl acetate. These will be present in varying quantities, depending on the choice of yeast and the successful progress (or lack thereof) of the fermentation. Which esters, alcohols and other compounds are produced are highly dependent on the temperature at which fermentation takes place. All of this will help to determine the character and nature of the sake. In this way, the choice of yeast also directly affects flavor.
Are All Yeasts the Same?
How does one strain of yeast physically differ from another? There are many ways, but not all are so obvious. It is often not simply a matter of size or physical appearance. In fact, when the cells of two yeast strains are seen next to each other in a microscope, the average person is not likely to be able to tell the difference.
The differences are more evident in other things. Like the length of the life cycle of the yeast: how long will it work before becoming dormant, or how robust it is against alcohol and/or temperature. Which alcohols, esters and other things it tends to produce as by-products of its life cycle during fermentation is of course, another important factor.
How is Yeast Developed?
Although we speak of yeast being "developed," it is more a matter of being isolated. The process of coming up with a new, specialized yeast strain, usually takes about three years, and is actually a kind of reverse engineering.
Yeast is usually isolated by starting with a tank of sake being made. It may be one in which many, many strains of naturally occurring (i.e. floating in the air) yeast strains were allowed to initiate the fermentation. Some of the thick foam on the top of the moromi (the fermenting mash) is taken and analyzed. This foam has the highest concentration of yeast cells in the tank. If the sake comes out well, the strain of yeast that is most populous is isolated and reproduced for further study. If it continues to demonstrate the desired qualities, it is made available on a larger scale.
History of Yeast in Japan
In the early 1900s, the Central Brewers Union first began taking pure yeast strains that had been isolated (usually by larger breweries from particularly good tanks of sake) and making them available to breweries across the nation in pure form , usually in small glass vials. These yeast strains have since been assigned numbers by the Central Brewers Union.
Common Yeast Strains
At present, they are up to number 15. Each one has its own special qualities. Yeast #1 through #6 are no longer in use, as apparently the acid produced was too strong.
Yeast #7, #9, and #10 are perhaps the most important today. Yeast #7, discovered by Masumi of Nagano, is the single most commonly used yeast in the country, with its mellow fragrance and robust strength during fermentation. Yeast #9 is the most common yeast for ginjo-shu, due to its wonderful fragrance-creating abilities, and fairly healthy constitution during fermentation. Yeast #10 produces a lower-acid, fine-grained flavor in sake, but is a bit fickle at all but the lowest fermentation temperatures.
More recently, Yeast #14 (which is low in acidity with lots of pears and apples in the fragrance) and Yeast #15 (which is very fragrant but not very robust) are often used in finer sakes, especially in particular regions.
There are, on top of the publicly available yeast strains, dozens of others that are used on varying scales throughout Japan. Many of these are proprietary, having been developed by breweries and used only by them, or more commonly, developed by prefectural brewing research institutes and used by breweries in that prefecture.
And finally, no discussion of sake yeast would be complete without mention of the awa -nashi kobo, or foamless yeasts. Yeasts #6, #7, #9 and #10 all have cousins that do almost an identical job without producing massive amounts of foam that are normally created throughout the course of the fermentation. These are designated by adding 01 to the number. For example, #901 is a foamless version of #9.
Why foamless? This saves hours and hours of grueling work, scraping the remnants of the foam from the side of a tank before starting the next batch. Also, since a third of each tank must usually be reserved for the rising foam, more sake can be brewed with less space using such foamless yeast. However, some experts say that the foamless versions are not quite what their foaming cousins are, in terms of the final product.
Why Pay Attention to Yeast?
Yeast is one of the newer developments in the sake world that we can all follow with interest. Over the last ten years or so, dozens of new yeast strains have been developed and come into use. This has been one of those great technical advances in the sake world -- one factor that separates the great ginjo of today from the run-of-the-mill sake of yesterday.
In the early 1900s, the Central Brewers Union first began taking pure yeast strains that had been isolated (usually by larger breweries from particularly good tanks of sake) and making them available to breweries across the nation in pure form , usually in small glass vials. These yeast strains have since been assigned numbers by the Central Brewers Union.
Koji
Just what is Koji?
Koji is steamed rice that has had koji mold spores cultivated onto it. This mold, for which the official scientific name is Aspergillus Oryzae, creates several enzymes as it propagates, and these are what break the starches in rice into sugars that can be fermented by the yeast cells, which then give off carbon dioxide and alcohol. Without koji, there is no sake. For what it is worth, sake is not the only beverage in the world using koji. There are a couple of others throughout Asia. But the brewing methodologies are vastly different.
A quick comparison between the production methods of sake versus other alcoholic beverages may prove useful. Wine is fermented from grapes, which already contain sugar (glucose, to be chemically correct). This is what yeast cells need for food. There are other kinds of sugars, but they cannot be metabolized by yeast. So in winemaking, yeast is added to a liquid already containing sugar.
Beer and other beverages made from malted barley begin not with sugars, but with starches, which are large molecules. Here, brewers employ enzymes brought out in the barley malting process (where the barley is moistened and warmed, i.e. the sprouting process begun) to break down the starches into sugars. These enzymes, which activate within very specific temperature ranges, reduce the starch chains into much smaller sugar molecules. Some will be glucose and feed the yeast, and some will be chemically different sugars adding to the flavor.
Sake is brewed from white rice stripped of its husk. There can be no malting, so the starch-reducing enzymes must come from somewhere else. This is where the Koji enters the picture. The dark-green spores, sprinkled onto steamed rice, provide the necessary enzymes to reduce the starch into sugars. There are many enzymes involved in this process. Some act to create fermentable sugar (glucose), others act more to create sugars that will not ferment but will instead affect texture and flavor of the sake.
Koji production (known as seigiku) is at the very heart of the sake-brewing process. The leverage it holds over the final product is immense. From a good beginning all things flow naturally, and so it is with koji. Koji is cultivated in a special room in the brewery called the koji muro. When ready, it is mixed with more steamed rice. Initially, yeast and water are added here. In later stages of a batch, koji is transferred into the large tank within which the sake-to-be is fermenting. It continues to do its sugar-making, while imparting the effects of its own sensitive production, until fermentation is finished.
In general, the koji-making process takes 40 to 45 hours. During this time, the developing koji is checked and mixed constantly to ensure proper temperature and moisture, as well as an even distribution of both. As the koji mold works its way into the center of the steamed rice grains, heat is generated. Different temperatures are ideal at different stages of the process. Not only that, but these ideals will change depending on the sought-after flavor profile. The type of rice, pH and mineral content of the water, and many other things affect the way koji is made as well. These variables compound to create a process that is more art and intuition than science.
When koji is ready for use, it looks like rice with a small amount of white frosting on each grain. The smell and taste are slightly sweet, as might be expected, as well as a characteristic light chestnut-like aroma.
In response to the demands of the times, there are several manifestations of automatic koji-making machines. Some of these are fully automatic. Insert the ingredients, wait for 42 hours, and your koji is ready for use. Others allow much more human intervention, some being only closed-loop temperature controlled tables. There are even robotic-finger koji mixers. All of these work well; some better than others. On the quality-versus-labor-saved curve, these score very high indeed. But it is interesting to note that almost every brewery in the country makes koji for their best sake by hand.