From the blog
How Mochi Is Made
Traditional mochi is made by steaming glutinous rice and pounding it, hot, in a giant mortar until thousands of grains fuse into one smooth, elastic dough. The ritual is called mochitsuki, and it takes two people, perfect timing, and a lot of trust. Modern mochi gets to the same chewy place with glutinous rice flour, water, and sugar, which is how mochi escaped the ceremony and entered the snack aisle.
Step zero: the right rice
Everything starts with mochigome, a short-grain Japanese glutinous rice that is a different variety from table rice. Its starch is almost pure amylopectin, the branched, water-loving molecule that makes things sticky and stretchy. Regular rice contains a second starch that keeps grains fluffy and separate; mochigome doesn't, which is why it can become one continuous, bouncy mass. (And no, "glutinous" has nothing to do with gluten; rice has none.)
Mochitsuki: the two-person pounding ritual
Here's how mochi has been made for over a thousand years:
- Soak. The rice is washed and soaked overnight, usually six to twelve hours, so water reaches the core of every grain.
- Steam. The soaked rice steams for about 25 to 30 minutes in stacked wooden frames called seiro, until translucent and sticky.
- Pound. The hot rice goes into the usu, a knee-high mortar carved from wood or stone, and the pounding begins with the kine, a long wooden mallet.
- Turn. This is the famous part. One person, the tsukite, swings the mallet. A second person, the kaeshite, darts a wet hand into the mortar between strikes to fold and moisten the dough. Teams shout rhythm calls like "Yoisho!" to stay in sync, because the calls are literally what keeps fingers attached.
- Shape. After ten to twenty minutes, when no individual grains remain and the mass is glossy and elastic, warm handfuls are pinched off and rounded on a starch-dusted table.
The fastest mochi team in Japan, at the Nakatanidou shop in Nara, pounds at up to three mallet strikes per second, hands flashing in and out between blows. The speed isn't for show: the hotter the rice when pounded, the softer and smoother the mochi.
What pounding actually does
The mallet is doing chemistry. Steaming gelatinizes the starch, meaning the granules swell with water and loosen into a soft network. Pounding then does three things at once: it ruptures the rice's cell walls to free more starch, it aligns and tangles those long amylopectin chains into a stronger web, and it merges every grain into a single continuous dough. The result is a viscoelastic material, one that flows slowly when pulled but springs back when released. That is the entire secret of the mochi chew, engineered with a hammer.
The modern shortcuts
Most mochi today skips the mortar without skipping the magic:
- Rice flour. Two glutinous rice flours dominate: mochiko (dry-milled, sturdy, everyday) and shiratamako (wet-milled granules that make a smoother, more elastic dough, preferred for fancy confections and mochi ice cream skins). Mix with water and sugar, cook, and the same starch network forms.
- The microwave. A genuine home method: whisk flour, sugar, and water, microwave in short bursts with stirring, and chewy mochi appears in about two minutes.
- Home mochi machines. Japan sells countertop appliances, like bread machines, that steam and then machine-knead soaked rice in one pot. Press STEAM, wait for the buzzer, press POUND.
- Factories. Commercial lines soak, steam, and machine-knead just like tradition dictates, then use encrusting machines that wrap dough around fillings and turn out tens of thousands of identical pieces per hour.
The hard problem: keeping mochi soft
Fresh mochi has one flaw: it starts firming up within hours. As the dough cools, its starch molecules slowly recrystallize and squeeze out water, the same process that stales bread, and refrigeration actually speeds it up. Solving that is the real science of modern mochi:
- Sugar binds water and blocks the starch from recrystallizing, which is why sweetened confection mochi stays soft for days while plain mochi bricks up overnight.
- Trehalose, a naturally occurring sugar that is less sweet than table sugar, does the same job even better, keeping commercial mochi soft in long storage without turning it cloying.
- Smart packaging handles the rest: Japan's shelf-stable mochi blocks are sealed with oxygen absorbers so they keep for a year or more with no preservatives at all.
A soft, shelf-stable mochi candy, the kind that can live in a pouch on a shelf and still chew like fresh, is that whole toolkit working together. It is a genuinely modern food-science achievement built on a thousand-year-old texture, and it's exactly the foundation Mochios is built on, with chocolate on top.
Japan pounds New Year mochi on lucky December 28, but never on the 29th: the date can be read as "double suffering," making it suffering mochi. The 31st is also out, since one-night mochi is considered rude to the New Year deity. Even the calendar takes mochi seriously.
From ritual to snack aisle
Mochitsuki is still a beloved New Year tradition, a neighborhood assembly line of steaming rice, flying mallets, and kids taking their turn at the usu. What's changed is everything around it: rice flour, food science, and machines mean the texture that once required a village can now live in a freezer, a bakery case, or a candy pouch. Start from the beginning with what mochi is, or taste-test the result in what mochi tastes like.