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Amazake (chè gạo)

Amazake is a Japanese sweet fragrant drink made from fermented rice. We fell in love with amazake at first sip at a tea house in Hakone after a long and exhausting hike. This was another serendipitous discovery. Tired of all the tourist attractions at Hakone, we decided to veer off our plans when we saw a trail head sign indicating a 45-minute hike. Little did we know that the hike included many extremely steep climbs so even the shortest route took us over 2 hours. We found a tea house after finishing the hike and ordered amazake based on the limited English description on the menu. As soon as we had our first sips of the hot, sweet and gingery drink, the waitress came over to ask if we got there by car, because otherwise, we’d need to hurry up to catch the last bus leaving in 5 minutes. We panicked, hurriedly finished our amazake and ran to the bus stop, only to find out that the last bus was to leave in 25 minutes. Phew. We were glad the waitress reminded us about the bus or we’d have had a lot of trouble finding our way back to Tokyo. But too bad the language barrier prevented us from fully enjoying delicious amazake.

Amazake stock

Even with such a short encounter, though, we still loved it so much that we couldn’t stop looking for amazake once we got back to the US. I lost count of how many times we got so excited when we saw things labeled as Amazake in Japanese and American supermarkets only to be let down. What we found in the States were marketed as and tasted like health food drinks. The amazake we had was more closely related to various species of rice puddings than wheatgrass  juice.

As with tofu-misozuke, when we couldn’t buy what we were so obsessed about, we set out to figure out how to make it. Luckily for us the Japanese markets in the Bay Area carry koji, a crucial ingredient in making amazake.


This drink is extremely easy to make: we cooked rice with more water than usual to get slightly wetter cooked rice, let it cool then mixed in koji (1 koji : 4 white rice ratio worked for us) and incubated the mix at 140F (60C) for 10-14 hours (our water bath set up was extremely useful in making this drink). Where we didn’t have a water bath, we heated water on the stove and monitored the temperature with a thermometer. It required more work and attention, but it worked. After incubation, the rice had the consistency of porridge and tasted really sweet, even though no sugar was added at any point during the process. This amazake was diluted 1:1 with water, brought to a boil, then simmered, and served hot with grated ginger as garnish. Mmmm… finally! The stock could also be used as sweetener in cooking and baking.

Happy with our success, and based on our observation that nếp than (black glutinous rice) was very fragrant on its own, we experimented with making amazake using black glutinous rice instead of white rice.

cooked black glutinous rice

Turned out the koji:rice ratio needed to be increased to 1:2 and incubation period needed to be stretched to 48 hours for the rice/koji mix to be turned into a sweet porridge stock. The husk on the glutinous rice didn’t get broken down, so the diluted drink needed to be blended well before serving. We loved our own version of amazake because the fragrance of black glutinous rice complemented the amazake fragrance very well. This drink was so flavorful and complex on its own that we didn’t even need to add ginger when served.

nếp than black glutinous rice) amazake

The next natural question in this series of experiments was whether we could passage amazake: can we make new amazake by mixing rice with amazake stock instead of koji?

Passaging amazake: white rice mixed with amazake stock instead of koji)

The answer was it depends 🙂 …we were able to passage white rice amazake but failed to do so with black glutinous rice amazake. We are still not sure why this was the case. Any chemists or microbiologists want to weigh in on this? One remedy we can try is to alternate our passages:

  1. make 1st generation amazake using white rice and koji,
  2. then mix 1st generation amazake with black glutinous rice to make the 2nd generation amazake,
  3. then use 2nd generation to mix with white rice to get 3rd generation,
  4. then use 3rd generation to mix with black glutinous rice to get 4th generation.

Don’t know if it’ll work, but we can try it and report back in the next post on this topic.

We are extremely happy that we can have good amazake whenever we want and can enjoy an additional variation of the drink by combining what we learned in Japanese cuisine with Vietnamese ingredient. Besides the passaging experiment mentioned above, next on our list to try is to experiment with different flavors (besides ginger). Our preliminary attempts with cinnamon and jasmine were underwhelming, so we’d need to think about this some more.

Mendelian arrangement of amazake from bottom left, counter-clockwise)

A note on the name: Since there isn’t an existing Vietnamese name for it, we made up the translation in the title (literally: sweet rice pudding) because a common naming formula for Vietnamese chè desserts is chè (sweet dessert soup/pudding) + main ingredient (e.g., đậu xanh (mung bean), bưởi (pomelo), đậu đỏ (red beans), bắp (corn), khoai môn (taro), hạt sen (lotus seeds)). I suppose we could have called it chè Nhật (Japanese sweet pudding) or cơm rượu Nhật (Japanese fermented rice). The problem with those names is that the first isn’t specific enough and the second is misleading, because amazake isn’t mildly alcoholic like the Vietnamese dessert of that name. We decided to stick with chè gạo, a new addition to the big family of chè 🙂

Finally, a biochemical digression: while freshly made amazake had a never-encountered-before fragrance, old stock amazake had an oddly familiar scent that once identified helped greatly in placing amazake in the grand scheme of things: old amazake smelled like kẹo mạch nha (maltose syrup, used in Vietnam to the same effects as maple syrup). Aha.

Home-brewers know that rice requires a 2-step fermentation because amylase is inactivated or otherwise unavailable in milled rice. Amylase is an enzyme essential for breaking down rice starch into fermentable sugar. The Japanese use koji mold and its amylase to accomplish this step, resulting in amazake. The next step involves converting sugar to ethanol using yeast. Amylase is also abundant in saliva – which is why thoroughly chewed rice tastes sweet, and some traditional alcohol recipes like chicha (Peruvian corn beer) call for spitting into the brewing vessel. However it’s accomplished, this first step in fermentation is called malting, and the resulting sugars are called maltose. Yup, that’s a scientific name.

The Vietnamese rice wine making process stopped halfway yields a sweet dessert, the aforementioned cơm rượu (fermented rice). It’s mildly alcoholic because both malting and alcoholic fermentation are happening simultaneously.

So we don’t need malting to make wine, but we do use maltose syrup on a lot of sweets – particularly drizzled in between a folded crispy crepe with grated coconuts and toasted sesame inside. The traditional recipe for making maltose syrup reveals another place where amylase can be found: in sprouted rice. Of course! Amylase is activated so the sprouted rice can convert its stored starch into consumable energy for the eventual seedling. Crushed sprouted rice is boiled with (glutinous) rice for 12 hours, strained & squeezed, and reduced to yield a thick, sticky, sweet, and fragrant syrup called kẹo mạch nha. Neat! Now where can we get some seed rice?


  1. Jonathan Partridge says:

    Fascinating. Koji is very expensive to buy in the UK. Is it the case that you only needed to use it once to make the first batch and then kept some over as a starter for subsequent batches?

    • Thanks for visiting Jonathan. Yes, we’ve found that a fraction of the amazake could be used as starter for the next batch. We haven’t done more than two passages, though, since amazake, for all the love it gets from us, is an occasional snack only. We usually start anew when we get the cravings again.

  2. It is the enzymes in the Koji that breaks down the starch in the rice into the sugary syrup.
    The koji mould will not be providing anymore new enzyme. Thus if you kept half the amazake and add new rice, you will only be left with 50% of the enzymes needed. And if you do it again in you will be left with just 25% of the needed enzymes thus this method will not work. It is different from sourdough or yogurt where the yeast or bacteris will keet doubling every few hours