LeftFlat / Right spherical
1800ml 4,180 yen (tax included)
720ml 1,980 yen (tax included)
5. Problems with flat-polished rice: "Reduction in umami flavor"
Even if flat polishing rice was not practical, there is another reason why Taketsuru Sake Brewery did not adopt it. That is, "reduction of umami flavor." Among the 20 types of amino acids that are produced when rice protein is broken down during the fermentation process, some are certainly substances that cause unpleasant flavors, but on the other hand, they also contain umami components such as glutamic acid. To achieve Taketsuru Sake Brewery's theme of "making food delicious," umami flavor, which has the effect of enhancing flavor, is essential. Also, the amount of umami flavor contained in sake is overwhelmingly greater than that of other types of alcohol, and umami flavor can be said to be the characteristic and advantage of sake.
Even if flat polishing reduces the unpleasant taste, it creates a new problem of losing the "sake-like" flavor of umami. This has its pros and cons. The reason why Taketsuru Sake Brewery does not polish rice excessively even with the conventional spherical polishing is the same.
Of the 20 types of amino acids, the four most common types that affect the taste of sake and their characteristics are shown in the following table.
Characteristics of the major amino acids found in sake
Other than alanine, undesirable tastes such as sourness, astringency, and bitterness stand out. While flat polishing rice to reduce the protein in the rice is expected to reduce these unpleasant flavors, it also reduces the umami flavor. Furthermore, it is said that basic (alkaline) substances in the last column of the table, "acidic/basic," are more likely to lead to unpleasant flavors.
6. "Flat-polished rice with germ left intact"
Advantages and disadvantages of "flat-polished rice with germ retained"
For comparison, we also decided to produce traditional spherical polished rice at the same time.
There is also a method similar to flat rice polishing called "original rice polishing". It is similar in that it can reduce protein more efficiently than spherical rice polishing, but it has the characteristic that less germ remains compared to flat rice polishing. We decided that it would be less effective in reducing unpleasant flavors and deterioration odors, so we did not adopt it this time.
Rice is a seed, and has a part called the germ that will eventually sprout. This germ part is usually removed when polishing rice into round rice, but when sake is made by deliberately adding it, the following is known about it.
I. The fat and protein in the germ increase the unpleasant taste.
II. Fermentation progresses too quickly, affecting quality
III. The yeast's ability to absorb amino acids increases, reducing both umami and unpleasant flavors.
IV. Basic amino acids are especially absorbed, reducing unpleasant flavors.
V. As a result of the increased absorption of amino acids, the amount of isoamyl acetate produced by yeast increases, improving the aroma.
Levels III to V do have some merit in improving the quality of the sake, but to achieve these effects, the germ of the rice used alone is not enough; in fact five times as much is needed, which is not only unrealistic, but also results in the off-flavors of level I being correspondingly worse.
With flat polishing, the rice is polished from the depth rather than the length, so depending on the degree of polishing, it is possible to retain the germ. Recently, research by the Hiroshima Prefectural Food Industry Technology Center has revealed that sake made using this "flat polished rice with the germ retained" can achieve the results from II to V above without adding any additional germ. Depending on how it is done, this could be a groundbreaking discovery. Since the germ is not added, there seems to be less of a concern about I. In addition,
VI. The germ component reduces the rate at which yeast die, resulting in a reduction in the smell of stale food.
We also found that the stale smell is produced by aging, and unlike the aged aroma, it literally deteriorates the quality. In order to achieve Taketsuru Sake Brewery's theme of "making food delicious," it is preferable to have sake with the deep flavor that comes from aging, but the stale smell is a drawback. Reducing this can also be considered an advantage. Also, a lower yeast death rate leads to a reduction in unpleasant flavors.
Although there is still a drawback in that the umami flavor is reduced, there are two advantages in that the unpleasant taste and maltiness odor are reduced. Moreover, there are four reasons why the unpleasant taste is reduced. Now there are all the reasons to make it.
