How Long Does Mochi (Japanese Rice Cake) Last?

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Japanese food is unique in that it rarely contains a lot of chemical preservatives. This includes their sweets, for which the Japanese are known to have a wide variety. One particular traditional favorite sweet treat of the Japanese is mochi, which is comprised of pulverized rice and sweetened and flavored before being molded into a little dome-shaped cake. Sometimes different flavorings are added too, such as melon or berry flavoring. Store-bought mochi has a short shelf life of a couple of months, but you can make your own mochi at home.

If you do make your own mochi, you are probably wondering how long does mochi last? To understand that, you have to understand what mochi is made of, how it is made, and why it is unlikely to last much longer than a few days outside of a refrigerator or freezer. (That’s right; a few days to a week outside of a fridge!) Let’s take a closer look at this cultural treat, how it is made, and how you can make it last longer when you can’t eat a ton of mochi yourself in one sitting.

Mochi Is Made of Gelatinous Rice Paste

Traditionally, mochi is made from moist rice that is pounded into a gelatinous paste. Making mochi has long been a tradition in Japanese culture for specific celebrations and as part of spiritual and religious ceremonies to produce mochi as offerings to Shinto gods. Whole rice grains are poured into a giant bowl that sits on the ground.

One person constantly adds water to keep the rice moist, while another person uses a sort of massive pestle to pulverize the wet rice into a paste. This continues until there is enough thick, sticky rice paste to begin shaping into balls or domes about one to one and one-half inches across. At this point, flavors and natural colors, such as red bean paste, may be added along with some sugar to sweeten it. During special holidays, the paste domes or balls may be wrapped in edible leaves, such as edible cherry tree leaves during the cherry blossom celebration every spring in Japan.

No Chemical Preservatives, Except Sugar

Rice will rot just as readily as any other organic substance. Given that this paste is no longer in the form of grains of rice, it is less likely to harden like white rice left on the table for a few hours. Instead, it will begin to break down, along with the added sugar, to ferment into unpleasant balls of mold.

Sugar provides a small amount of preservative protection, and if you make mochi with cornstarch, that may help as well. However, these ingredients in mochi will not stop it from deteriorating completely. A week at best outside of the refrigerator is possible, and only if the mochi is in a sealable container or rolled in plastic wrap or foil wrap to keep bugs away and prevent it from being exposed to the air.

Keeping Mochi in the Refrigerator

Keeping mochi in the refrigerator does extend its “shelf life” a little, but not by much. You will need to roll it in a protective wrapping or store several mochi balls or mochi domes in a sealable container. Make sure the container’s lid does not have any holes or cracks in it, and close it tightly.

In a refrigerator, you should be able to keep mochi an extra week to two weeks. After that, the very dry conditions in the refrigerator and the very moist mochi will develop into a mess that is half dried out, half mold. If you cannot eat all the mochi you make within two weeks, it is advisable to freeze what you think you will not be able to eat in the next couple of weeks.

Keeping Mochi in the Freezer (not recommended)

The flavorings you use to make this Japanese treat palatable can also become flat if you store the mochi in the freezer. It will be great if you finish it sooner than later to avoid destroying the tastes and flavors of the mochi.

A Word on Mochi Ice Cream


A new mochi treat to hit the grocery store freezers as of late is mochi ice cream. Small balls of ice cream are used in place of traditional fillings inside mochi balls or domes. These all have to be refrigerated consistently to keep the ice cream from melting, and they are individually wrapped for freshness.

You could try making mochi ice cream too. You will first need to master the fine art of creating filled mochi desserts that do not require that you freeze them. When you are comfortable with shaping and filling mochi that does not contain ice cream, then you can attempt to create mochi ice cream balls.

Mochi ice cream from a store will have added preservatives in it because it is a manufactured product that includes dairy food. However, you can make your own ice cream (sans preservatives) and make your own mochi. If you do this, you will need to consume your homemade mochi ice cream within two weeks of making the balls and wrapping them up to freeze.

Related Questions

Now that you see how to make mochi, what goes into mochi, and how long mochi cakes and mochi ice cream cakes will last, you probably have some additional related questions. Some of those questions and their answers follow.

How Do I Get Started With Making Moshi at Home?

Making mochi at home the traditional Japanese way is very complicated. Thankfully, modern machines have made this process easier. You can actually buy mochi makers to use at home on your kitchen counter. They process moistened mochigome rice into paste and dispense it like a soft-serve ice cream machine. What you do with the paste after that is up to you.

Are There Mochi Molds to Help Me Make the Perfectly Shaped Mochi Balls and Domes?

Yes! There are plenty of supplies and kitchen equipment pieces that can help you shape your mochi paste into balls and domes. If you also want to put fillings into your mochi, or create another authentic Japanese mochi with a whole strawberry in the middle, there are additional implements you can buy to do just that. Be sure to follow the instructions to keep your mochi from sticking to the molding pans.

Where Can I Buy Mochigome Rice?

Go to an Asian food store and request the mochigome rice like this. If they don’t have the actual rice, they may have the flour. The flour is often used to make another Japanese treat, dango, but you can use it to make mochi in a pinch. If you are stuck on the idea of using the rice and creating the paste yourself, you may have to go to several Asian grocers to find what you are looking for.

See Also:
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Japanese Ketchup vs. American Ketchup: Read This First!
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13 Street Foods in Japan
What Does Oolong Tea Taste Like? Read This First!

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