The premium categories of sake are beautiful in their simplicity. They consists only of the simple raw ingredients of rice, water, koji (rice propagated with a special mould), and sometimes a small amount of brewers alcohol added to draw out more delicate flavours and aromas. Of these ingredients, it is very often rice that assumes the role of vanguard in any marketing or promotion. However, in truth, the relationship between the rice used and the quality of the final product is significantly weaker than it is, for example, with grapes in wine production. Great sake can be, and often is for that matter, made from rice that is deemed to be "lower grade", classified as table rice, or ippan-mai in Japanese.
In contrast to wine production, the overriding factor determining the quality of sake is actually the brewing process, and a tight, well honed process will invariably prevail against that of a poor one, even if the latter uses the finest of raw ingredients. A skilled and experienced master brewer (toji) has several other tools at his or her disposal that can be more significant in altering the course of any given batch. For example, legendary British toji Philip Harper describes the role of koji as being a "filter" that obscures the characteristics of a particular year's rice harvest. This opinion is echoed by many other professionals in the industry who place this miracle mould above anything else on the list of the most influential factors in sake brewing. Indeed, the process of converting starch to sugar as a result of enzymes from the koji is one of the fundamental differences separating wine and sake production.
That being said, the importance of rice in sake brewing should not be underestimated, and the variety used also still plays an important role in determining the characteristics in the final product. In the case of sake, though, the influence of the rice variety is more closely linked with how much easier it is to handle during production, or perhaps more accurate to say, how less difficult some strains can be. Indeed, some have a reputation as being slightly more challenging to work with than others, with a few even being deemed downright challenging. When you consider the importance of the brewing process in making good sake, it stands to reason that using quality raw ingredients goes a long way to alleviating the many difficulties facing a team of brewers. Therefore, using rice specially cultivated for sake production is more about instilling a bit more confidence through stability when carrying out the numerous delicate processes necessary when making premium sake.
These special strains of rice, known as shuzokoutekimai in Japanese, typically have a lower protein content than regular table rice, and can often be identified through the presence of a prominent starchy centre known as the shinpaku. This lower protein content often leads to fewer so-called "off-flavours" in the finished sake, and the presence of a comparatively high starch content also aides numerous other processes. The ideal characteristics of a brewer's rice is one that is durable enough to sustain a high degree of polishing, has an ability to consistently absorb water when being soaked in preparation for steaming, and one that allows for excellent haze (koji mould) penetration when making koji. All of these attributes are welcomed in sake brewing, yet they are also the reason that brewer's rice is said to be unsuitable for eating. However, this last point is of course very much a subjective one.
Generally speaking, rice is divided into two categories depending on whether it is a late or early harvesting variety. In Japanese, these are known as okutei and wasei respectively. Although it is often difficult to make accurate generalisation in sake, for the vast majority of cases, late harvesting rice can be said to be softer grained than early varieties. This in turn means that they will dissolve more readily in the main fermenting mash and go on to produce sake with a fuller-bodied, richer profile. Conversely, early harvesting rice tends to be hard grained, and are known for dissolving gradually, producing a clean, lighter style. Notable examples of both would be Omachi, famously late harvesting and very difficult to handle when brewing, and Gohyakumangoku, an early harvesting variety synonymous with Niigata prefecture and the famous light and crisp tanrei-karakuchi style. It is also worth noting that you might occasionally hear the term nakatei for rice that is harvested mid-season.
In summary, rice specifically intended for brewing with and regular table rice are as different from one another as grapes sold in supermarkets intended for consumption are when compared to those made for wine making. Naturally, the price difference between these two types is also considerably different, and the cost of procuring the most sought after examples is perhaps the most significant expense facing sake breweries. Although using regular rice can still produce exceptional sake, the stages of the brewing process that are said to have the greatest leverage in determining the final characteristics are made much easier when using quality rice. For this reason, the vast majority of sake submitted to the National New Sake Competition (zenkoku shinshu kanpyo-kai) each year is made with the most expensive and well known brewer's rice of them all, the infamous Yamada-nishiki.
Although Yamada-nishiki exhibits all of the qualities of a good brewing rice as mentioned previously, it is formidably expensive, and it does not grow well in every region of Japan. Moreover, customer preferences vary, and the industry is lucky enough to boast another 100-120 or so varieties. From within these, there also exists a wide spectrum of possible subtle flavours, and sometimes even aromas, that can manifest when used to their potential. In the right hands, these subtle yet unique characteristics can add the final touch of personality to a particular sake. For this reason, savvy consumers often base their decision as to what to buy purely on which rice variety was used.
If nothing else, the role of rice in the greater overall world of sake is one that offers a fascinating insight into the rich tapestry of regionality in Japan, and the influence this can have on sake production. In some cases, entire regions have been moulded by the varieties of rice that they produce, and certain varieties have even come to define them, transcending branding as the most important component. Because of this, anyone serious about studying the numerous different facets of sake will at some stage invariably have to dedicate some time to this subject. However, the rewards for doing so will undoubtedly be a greater appreciation of how intricate and complex the world of sake can be. Therefore, the varieties listed below are just a small sample to get you started, and comprises the top four most popular rice varieties by volume.
A native of Hyogo prefecture in western Japan, Yamada-Nishiki was developed back in 1936 by cross-breeding the female strain Yamada-bo with that of the male Tankan Wataribune. As a result of its reputation as being easy to handle, and often resulting in billowing flavours and pronounced aromatics, Yamada-nishiki is considered to be the quintessential thoroughbred strain, and the epitome of what makes a suitable rice for brewing premium sake. This reputation has earned it the nickname as "The King of Brewers Rice", and it occupies the #1 position as the most used rice by volume by a substantial margin. Despite also having a substantial price tag, it is widely distributed throughout Japan and is grown in several other regions, particularly within western Japan.
Yamada-nishiki is a late harvest variety, and its relatively tall stalks make it particularly challenging for the farmers to cultivate, especially considering Hyogo prefecture is prone to typhoons at the beginning of August, right around the same time that it is due to be harvested. However, the pay-off for enduring these difficulties during cultivation are its large grain size with a prominent shinpaku. Furthermore, as it contains relatively less fats and proteins than other strains, it is often reassuringly predictable when brewing. In particular, it dissolves consistently in the mash, often leads to vigorous and healthy koji, and performs well when washed and soaked. All of this has led to Yamada-nishiki being the rice of choice when making the higher classifications of sake, and its name dominates the entry sheets at each of the annual National New Sake Competitions.
Registered in 1957, Gohyakumangoku is synonymous with the eastern Tohoku region. The name was chosen to celebrate Niigata farmers reaching the 500 million koku production milestone, the traditional unit of measurement for both rice and sake. Previously occupying the #1 spot, it was finally surpassed by Yamada-nishiki for total volume back in 2001. However, still safely occupying the #2 position, its popularity has remained strong with brewers. Currently, it is cultivated in 21 prefectures across Japan, including the famous brewing region of Hokuriku that comprises of Toyama, Ishikawa and Fukui prefecture.
Gohyakumangoku is an early harvesting variety, and is therefore slightly hard grained, dissolving less readily in the mash. This tends to lead to leaner flavours, and more muted aromas than say Yamada-nishiki. Furthermore, because of its large and centred shinpaku, the rice kernels are prone to cracking during polishing. This makes it less suited to making the higher grades of dai-ginjo and junmai dai-ginjo sake that require polishing ratios above or equal to 50% of the original weight. However, the large shinpaku is ideal in koji production, and it is said to be especially suitable for use with a koji making machine.
Miyama-nishiki originated from the mountainous region of Nagano prefecture, and is by far the youngest strain on this list, first being cultivated as recently as 1978. Despite having tall stalks that make it more challenging during cultivation, Miyama-nishiki has a strong endurance to cold weather and is harvested mid-season. This makes it ideal for cultivation in regions with a higher altitude that are not suitable for other less durable strains. Indeed, when it was first discovered as a result of exposing another rice strain, Takane-nishiki, to gamma radiation, the white starchy centre was so prominent that it was named after the snow capped alps for which Nagano is famous.
Like Gohyakumangoku, Miyama-nishiki is also hard grained, and therefore doesn't dissolve easily during fermentation. As a result, it often leads to cleaner sake, with subdued aromas. Currently, this variety occupies the #3 position in terms of total production, and is cultivated in 7 prefectures, nearly all of which are located in the colder Tohoku region in eastern Japan.
Named after the small village where it was first cultivated, now Naka Ward in present day Okayama City, Omachi traces its history all the way back to 1862. This makes it the oldest pure strain of sake rice to have enjoyed continuous cultivation, and its genes permeate deep into the current crop of modern lab produced varieties. Although production is just 1/10 of Yamada-nishiki, it is Omachi that garners an almost cult-like following amongst sake drinkers. This popularity is most likely due to its appealing back story as a natural pure strain, and the more refrained, sometimes slightly herbaceous flavours that it produces.
Large grained, and famously late harvesting, Omachi has a reputation as being both difficult inside and outside of the brewery. For the farmers, incredibly tall stalks, made worse by the aforementioned late harvest, causes no end of stress during the typhoon prone summer and early autumn seasons in Japan. Furthermore, the resulting rice is soft, with a large, rounded shinpaku, making it particularly difficult to handle inside the brewery. More specifically, it is known to be fast melting during fermentation, and therefore, great skill is needed from the brewers to reign it in. Extra care is also needed when soaking and steaming to make sure that it doesn't soak up too much water that would make it even softer before tasks such as koji making and mashing can begin.
However, the payoff for enduring the challenges that Omachi presents is more than justified in the final sake. The fact that Omachi has endured, when the vast majority of older strains were replaced with more modern, easier to cultivate, hybrid strains is testament to the wonderful characterful sake that is produced from this heirloom rice. Omachi remains highly prized, not just in its home prefecture of Okayama, but in many other prefectures outside of Japan, with some brewers going as far as to only brew with Omachi. Although cultivated in a few other prefectures, the best Omachi still comes from Okayama prefecture, and it remains the most prominent aspect of the regions sake industry.