Trying Out Different Rice Varieties
Belated happy New Year to you. How did your 2023 begin? Mine started with koji making and miso preparation for the coming years.
I have recently been experimenting with several varieties of rice and wanted to share my experience with you. Last year, I wrote about “Rice for Koji to Make Sake and Miso”. Today, I want to talk about the size difference mainly.
First, short-grain rice is used for general koji making, although in some Western countries long-grain rice such as Jasmine or Basmati is used. Living in Europe, I often use Koshihikari rice grown in Italy, such as Yumenishiki. The grain is approximately 5 mm long, absorbs water easily and takes about an hour to steam. This year, as that rice was not readily available, I happened to have the opportunity to try a number of different varieties.
One is Utage from Vietnam and the other is Tosya Pirinc, a risotto/paella rice from Italy or Turkey. Other Italian risotto rice of various classes exist, such as Arborio, Carnaroli and Orginario, which can be used to make koji.
From the left: Yumenishiki, Utage, Tosya Pirinc risotto/paella rice
One major difference, however, is that when the rice is cooled down to about 40°C after steaming and before inoculating with koji spores, there was a big difference in the way the rice dried out.
Rice with large grains, such as risotto rice, has a high moisture retention rate and does not lose moisture so quickly when spread out immediately after steaming. In contrast, rice with smaller grains, such as Utage, has the problem that if it is spread out and mixed slowly over time to lower the temperature, it dries out relatively quickly in the process of lowering the temperature.
In koji making, once the moisture has been lost from the rice, it cannot be restored. Spraying water is also not a good idea. It only wets the surface but does not penetrate into the rice, and rice that is wet on the outside invites the possibility of bacteria nesting in some cases.
As a solution:
- Do not spread the steamed rice immediately, but leave it wrapped until the temperature drops to a certain extent.
- Lower the temperature of steamed rice in a humid environment.
Moisture is essential for koji germination, so a major key is how much moisture is retained in the rice on the first day.
On the other hand, risotto rice had the advantage that its surface remained relatively unsticky after steaming and was easy to break apart during cooling.