How to preserve Japanese rice

How to preserve Japanese rice

As you may know, rice is a staple food in Japan, and it’s deeply rooted in Japanese history and culture.
Over the years, we learn not to waste rice, not even the last single grain. This is a way to show our respect and gratitude to God, nature, farmers, and also to whoever cooked the rice. The Japanese word いただきます (itadakimasu) contains this spirit, and Japanese people have the custom to say this word before eating rice and any other food.

I think this Japanese tradition also applies to the current issue of “food waste”. It’s not easy to cook just the right amount of rice. So we usually have leftover rice.
As a food education instructor, I’d like to tell you the proper way of preserving Japanese rice so that you don’t need to waste food.

How long rice can be kept warm in a rice cooker?

Nowadays, most Japanese people use electric rice cookers with an automatic keep-warm function. So, we can eat warm rice anytime.

However, keeping it warm for a long time is not recommended. It makes the rice too dry and the taste becomes worse.

The amount of time you can keep it warm depends on the quality of your rice cooker. If you have a high-quality rice cooker, it should be ok to keep rice warm for 24 hours.
However, it’s usually said rice cookers can keep the rice warm for up to 12 hours. Please check the instruction manual of your rice cooker just in case. Also, if you want to enjoy the flavor of freshly cooked rice, it’s said, 5 to 6 hours is maximum.

The risk of food poisoning

Keeping rice warm in a rice cooker is relatively safe in terms of food poisoning. Most of the bacteria doesn’t grow at a temperature under 10℃/ 50℉ and upper 60℃/ 140℉.

The keep-warm function must keep the rice at a high enough temperature. So, don’t leave it in the rice cooker after you turn off the function.

However, you shouldn’t rely on the temperature too much.
Always Keep the shamoji/rice paddle clean.
Don’t return leftover rice to the cooker.
My advice to you is “try not to bring the bacteria into the rice cooker”.

How to preserve leftover rice?

What do you do when you don’t have any plans to eat cooked rice within 12 hours? It may be a good idea to preserve the rice in the fridge to prevent food poisoning.
However, Japanese sticky rice has a lot of starch in it, and it deteriorates at 0℃ to 3 ℃ (32℉ – 37.4℉). So, rice dries out and the texture becomes worse in the fridge.

Freezing is better than refrigerating to keep the taste of cooked rice. There are many types of containers for freezing rice. Even though they vary in shape and size, most of them are in the same size as a rice bowl.

If you have a container like them, fill it with cooked rice and properly shut the lid while the rice is still hot. When the rice becomes cool to room temperature, freeze it.

You can also wrap the rice with plastic wrap and put it into Ziploc or something equivalent. Whether you use a container or Ziploc the way of freezing is still the same.

Either way, reheat the rice with a microwave before you eat it.

Preservation of room-temperature rice from traditional to current way

As I said at the beginning, Japan has a long history of rice. Of course, there was no rice cooker with a keep-warm function in the past.
After the rice was cooked with a special pot called お釜 (okama) or 土鍋 (donabe)/earthen pot, the cooked rice was transferred to a wooden tub called お櫃 (ohitsu). Ohitsu has an antibacterial action and it also keeps the rice desirably moist.

This traditional way is starting to become popular again. Some people say that the rice preserved in ohitsu is more delicious than the rice kept warm in a rice cooker.

Using a ceramic ohitsu is convenient. You can use it the same as wooden ohitsu and throw it directly in the microwave to reheat it.

Bamboo skin also has antibacterial action. In the old days, people wrapped some rice balls with bamboo skin and brought it with them for lunch.

Nowadays, the bamboo skin is hardly used for it. However, we still have the food culture of brining rice with us as bento, and most of the time room-temperature rice is in it.
When you pack rice into the bento box, be sure you let it cool completely. The moisture from the steam of the hot rice may cause food poisoning.

Adding “umeboshi” (salted Japanese plum) is an effective way of preventing food poisoning. You can often see it in Japanese bento.

An antibacterial sheet that contains silver ion is commonly used for bento. There are various designs of it.

I used it during the summer when I made bento for my kids. The way of using it is quite simple. All you have to do is put the sheet on the top of your bento.

I believe that freshly cooked rice is the most delicious and safest. However, we also enjoy eating room-temperature rice with caution. Don’t leave leftover rice for a long time. Especially, leaving it at 30℃ to 40℃ (86-104℉) is the riskiest for food poisoning.

Please enjoy delicious Japanese rice safely!

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