When researching sake, you will come across the term Rice Polishing Ratio (RPR). But what does this important term mean? In this article, we'll delve deeper into why the sake rice polishing ratio is discussed so often and how it determines the sake flavor.
The most common type of rice is the white grains that everyone eats. However, you also get brown rice, which is actually the original form, and to make it edible, the outer layer must be shaved off. The same is done when brewing sake, so the rice polishing ratio refers to the percentage of rice remaining after the original brown layer is removed. For example, if a bottle of sake has a 60% rice polishing ratio, that indicates that 40% of the outer layer was removed from the original grain of rice.
Keep reading to learn more about why this is important in sake and how it’s done.
CONTENTS
Why is Sake Rice Polished?
Rice Polishing Ratio and Nutritional Value
Rice Polishing Ratio and Sake Types
Is a Higher Rice Polishing Ratio Better?
Rice Polishing Innovations
Chemicals in the Rice Milling Process
The appearance of Polished vs. Unpolished Rice
Find Your Favorite Sake by Rice Polishing Ratio
Why is Sake Rice Polished?
The reason for polishing rice is closely related to its components. The center of the rice grain contains a large amount of starch, while the outer layer is rich in lipids, vitamins, and proteins. In the case of regular table rice, the lipids and proteins in the outer layer are valued for their flavor. Hence, the milling ratio is usually around 90%.
On the other hand, for brewing sake, proteins and lipids contribute to essential taste elements, such as umami and bitterness. However, if their levels are too high, they can negatively affect the aroma and taste, creating an off-flavor. This is why more thorough milling is required for sake production.
Rice Polishing Ratio and Nutritional Value
The higher the rice polishing ratio, the lower the nutritional value of the rice. Brown rice is high in vitamins B1 and B2, dietary fiber, and minerals, but these nutrient values get lower when the rice is white. White rice still contains carbohydrates and protein, but the lower the rice polishing ratio, the fewer nutrients in the rice.
Sake is known for being one of the healthiest alcoholic beverages because it contains many amino acids and nutrients, as we mentioned above. So, sake with a higher rice polishing ratio (less rice removed) keeps more nutrients, making it a good choice if you're health-conscious.
Rice Polishing Ratio and Sake Types
As we discussed in our Sake Guide overview, the rice polishing ratio and ingredients determine the different sake grades. Sake that does not fall into any of the eight categories of Tokutei Meisho-Shu is called "normal or general Sake."
On the other hand, all premium sake contains less than 10% brewing alcohol by weight of white rice. The rice polishing ratio determines which category a sake falls into. For example, a sake made with rice shaved to less than 50% of its original size and without any added brewer’s alcohol is classed as Junmai Daiginjo.
Is a Higher Rice Polishing Ratio Better?
A low rice polishing ratio does not necessarily mean that the sake is inexpensive or that a high polishing ratio guarantees a higher quality sake. In fact, at a sake competition in Paris in 2018, a brand with a rice polishing ratio of 77% won an award!
Factors such as the brewery's technique, the type of rice and water used, how it pairs with food, and the story behind the brand all contribute to the value.
Rice Polishing Innovations
Did you know that sake with a rice polishing ratio of 1% or less is now available in 2023? Rice milling machines have become more advanced, with some even using optical sensors to measure the degree of hull removal, which guarantees higher polishing precision.
Chemicals in the Rice Milling Process
Some people question whether chemicals are used during the rice milling process, and this isn't the case. However, depending on the rice farm, pesticides may have been used during cultivation.
That said, in Japan, standards for pesticide use are strictly regulated, and rice with pesticide residues exceeding these standards can not be eaten or used to make sake. That's why recently, sake made from pesticide-free rice has been a growing trend.
Here at Sakura Town, No Nature No Life and Hotaru are both pesticide-free sake that you can enjoy knowing that the utmost care has gone into making them.
The appearance of Polished vs. Unpolished Rice
As rice is polished, the grains become smaller. Generally speaking, the higher the rice polishing ratio, the more beautiful and clear the color of the sake will be. Plus, the more refreshing the taste is with a fragrant aroma and enticing flavor. Remember what we mentioned earlier, though, that the rice polishing ratio alone does not determine the value of sake.
Find Your Favorite Sake by Rice Polishing Ratio
The rice polishing ratio is an inseparable part of the sake-making process. If you feel overwhelmed by the number of sake brands to choose from, why not try selecting one based on the rice polishing ratio instead?
It's a fun way to discover the different types of sake, and it will help you understand your likes and dislikes.
For more of our informative sake articles, see our blog, where we cover many different topics related to this tasty Japanese beverage.