Can I keep onigiri overnight? Here’s what to keep in mind

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Many fans of Japanese food wonder if it’s okay to store fresh onigiri (Japanese rice balls) overnight, to be enjoyed for lunch or at a picnic the following day.

Can I keep onigiri overnight? How to keep your rice balls

The short answer is yes, but it’s important to keep certain facts about onigiri in mind.

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What is onigiri?

Onigiri is a Japanese snack often eaten as an appetizer or for lunch. It consists of a ball of rice, a savory filling, and an outer coating or nori wrapper.

Onirigi ingredients

The main ingredient in onigiri is rice, and the best rice for making onigiri is short-grain rice, also known as Japonica or sushi rice.

After cooking the rice, it is formed into small, bite-sized balls or three-dimensional triangles with the hands.

Indentations are then made in the rice balls and are filled. Popular fillings include salmon, tuna, shrimp, chicken, pork, and cod roe. Cooked vegetables also can be used.

After the onigiri is filled, it is wrapped in nori strips. These dried seaweed strips serve as holders.

Alternatively, larger sheets of nori can be used to completely envelop the onigiri, or the rice ball can be rolled in sesame seeds, or even in roe.

Learn how to cook sushi rice without a rice cooker here

Onigiri storage

Rice and its fillings can spoil if not stored properly. This is especially true for certain fillings, such as seafood, chicken, and mayonnaise.

Although some store-bought onigiri contains preservatives, not all do, and homemade ones definitely do not.

Although many times you will want to consume your onigiri the instant they are made, there will be occasions when it’s more convenient or necessary to wait.

This is not only possible, but it’s also quite easy.

When onigiri is molded by hand, the cook rubs salt on his or her hands first. Salt acts as a natural preservative to some extent. But to ensure safe storage overnight, onigiri needs to be wrapped up tightly in cling wrap.

This will keep bacteria from growing, and will also help to maintain the onigiri’s freshness, moistness, and texture.

For an extra layer of insulation, you can then place the onigiri in a zippable plastic bag and pop them in the refrigerator.

But since refrigerated rice tends to get hard when stored at cold temperatures, another helpful trick is to wrap the already sealed bag with a kitchen towel. That way, the rice doesn’t get too cold.

You can even freeze onigiri. After putting them in a zippable bag, suck as much excess air out of the bag as possible, using a straw.

To thaw, place unwrapped onigiri in a microwaveable bowl and microwave just until warmed through.

Storing homemade onigiri

If you make your own onigiri, you can wrap them in foil packages prior to storage. This not only adds an extra layer of protection, but it adds to the fun when you open up your snack the next day.

Here’s how to do it:

  1. Cut nori into half-inch strips that will be used for wrapping around the center of your rice balls. Or, if you prefer, you can use nori strips that are slightly wider than each ball.
  2. For each onigiri, cut out a square of aluminum foil that is a little more than twice as wide as the onigiri.
  3. Stick a piece of masking tape along the center of the foil, extending an inch or two on either edge.
  4. Turn the foil over.
  5. Position a strip of nori vertically in the center of the foil.
  6. Fold the sides of the foil inward, meeting at the center.
  7. Brush the foil with a little sesame or olive oil.
  8. Place a rice ball on the upper third of the foil piece.
  9. Fold the foil over the rice ball, from bottom-up, to enclose it.
  10. Use masking tape extensions on both ends to seal the package.

What NOT To Do

  • Don’t leave onigiri out on the counter for more than a few hours, especially in hot weather.
  • Don’t use cool or leftover rice when making onigiri. It will not be moist enough to begin with, and it will dry out even more when stored.
  • Don’t leave nori on your onigiri when storing them unless you wrap them tightly and consume them relatively soon. Nori can get soggy in the refrigerator. You may wish to remove the nori before storing, and then wrap more nori around your onigiri later, before serving.
  • Don’t store onigiri in the freezer for more than a few months, because of the possibility of freezer burn.

So, keeping the above information in mind, go ahead and order extra onigiri at your favorite Japanese restaurant or takeout venue (or make a large batch of your own).

If it turns out that your eyes were bigger than your stomach, you can rest assured that those leftovers will be just as good the next day.

Read next: How many onigiri do you need for lunch? Make it a complete meal like this

Check out our new cookbook

Bitemybun's family recipes with complete meal planner and recipe guide.

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Joost Nusselder, the founder of Bite My Bun is a content marketer, dad and loves trying out new food with Japanese food at the heart of his passion, and together with his team he's been creating in-depth blog articles since 2016 to help loyal readers with recipes and cooking tips.