One particular type of "Sake rice" is the so-called "Shuzo Kotekimai," the "Rice ideally suitable for sake brewing." These are specially developed and cultivated strains of rice that possess certain qualities that make them most suitable for sake-brewing (they are not suitable as rice for at dinner!). About 30% of all sake rice (so roughly 2% of all rice grown in Japan) is "Shuzo Kotekimai."
Rice contains various elements, some of which are good for sake brewing, others much less so. Here are the five main elements:
- Carbohydrates (starch): 70-75%. By saccharification or liquefaction this becomes sugar. The most important element in sake brewing - the more starch (the larger the grain) the better!
- Proteins: 7-8%. Changed into amino acid by the enzymes produced by the Koji. Bad for fermentation.
- Chemical elements. Necessary for the growth of micro-organisms and therefore good for the brewing process. There are 4 kinds: potassium, phospohoric acid, magnesium, calcium.
- Lipids: 2%. Concentrated in the germ. Influences the aroma of the sake in a negative way.
- Vitamins. Concentrated in the germ, also not necessary for sake.
Only 1 and 3 are good for fermentation. "Sake Kotekimai" will have much of these and less of the others. The three most important qualities of "Sake Kotekimai" are:
- Have a large grain (1,000 grains should weight 25-30g, against ordinary rice only 20g (the famous Koshihikari and Sasanishiki types weigh 22-23g). As individual grains are so small, rice is weighed in units of 1,000 grains, called "Senryuju.")
- Have a soft opaque white center called "shinpaku," a sort of "white heart." This is pure starch.
- Have only little proteins and fats.
The large grain is of course necessary for super premium sakes (such as Ginjo), where the grain is polished to 60%, 50% or even less of its original volume.
Types of "Shuzo Kotekimai" are:
- Omachi from Okayama Prefecture, the oldest variety, developed in the Edo period.
- Yamada Nishiki, the most famous variety, very suitable for Ginjo sake, developed in Hyogo Prefecture in the 1930s. 30% of all "Shuzo Kotekimai." Has been called the King or Yokozuna of Shuzo Kotekimai.
- Gohyakumangoku from Hokuriku and Tohoku. 50% of all "Shuzo Kotekimai."
- Miyama Nishiki from Nagano Prefecture.
- Hattan Nishiki from Hiroshima Prefecture
Unfortunately, demand for "Shuzo Kotekimai" far exceeds supply. This rice is very difficult to grow, because it stretches to 120 cm (against normal rice 90 cm), making it prone to devastation by typhoons. It must be placed wide apart (double from ordinary rice) and is a late harvesting type. Not for nothing that it costs double the price of ordinary rice (600 yen per kilo)!
So generally speaking, the special rice is used for the premium sakes (also about 30% of all sake brewed in Japan), while "ordinary sake rice" is used for the Futsushu or "ordinary sake" with added alcohol.