How to Make Koji Amazake: Homemade Japanese Fermented Rice Drink

What is amazake

Amazake is a traditional Japanese fermented drink. With its gentle sweetness and smooth, thick texture, it's so nutritious it's called "drinkable IV drip."

There are two main types of amazake. Learn the difference to choose what suits you.

Two types of amazake

Koji amazake

Made by mixing rice koji with cooked rice and incubating at 55-60°C for several hours. Koji enzymes break down starch into sugar, creating natural sweetness without any added sugar.

Zero alcohol, safe for children, pregnant women, and non-drinkers.

Sakekasu amazake

Made by dissolving sake lees (sakekasu) in hot water with added sugar. Contains trace alcohol from sakekasu, so caution is needed.

This article covers koji amazake: alcohol-free and nutrient-rich.

Why it's called "drinkable IV drip"

Koji amazake contains these nutrients.

• Glucose: Sugar that quickly converts to energy
• B vitamins: B1, B2, B6, niacin, involved in energy metabolism
• Essential amino acids: All 9 that the body cannot produce
• Dietary fiber and oligosaccharides: Support gut health

Its nutritional profile resembles IV fluid composition, earning the nickname "drinkable IV drip."

How to make koji amazake

Ingredients

• Dried rice koji: 200g
• Cooked rice: 300g (about 1 cup)
• Water: 400ml

Rice cooker method

Using the rice cooker's keep-warm function is the easiest method.

1. Mix rice and water

Add cooked rice and water to the inner pot, mix well. If rice is very hot, add water to cool to about 60°C.

2. Add rice koji

Once rice cools below 60°C, crumble in the koji and mix thoroughly. Too-high temperature deactivates enzymes, so always cool below 60°C first.

3. Keep warm for 8-10 hours

Set rice cooker to "keep warm" mode. Don't close the lid fully; drape a cloth and leave a gap to prevent overheating.

Stir every 2-3 hours and check temperature. Maintaining 55-60°C is critical. Too high deactivates enzymes; too low slows fermentation and risks contamination.

4. Sweet means done

After 8-10 hours, taste. If noticeably sweet, it's ready. Rice grains should be soft and the mixture thick and smooth.

Thermos method also works

If you can't tie up the rice cooker, use a thermos. Heat rice and water on the stove to 60°C, add koji, mix, then pour into a pre-warmed thermos for 8-10 hours. Temperature drops gradually, so sweetness may be slightly milder.

Temperature control tips

Temperature control is the most critical factor.

• 55-60°C: Enzymes work most actively. Keep in this range
• Above 65°C: Enzymes deactivate; won't become sweet
• Below 50°C: Fermentation slows, bacteria risk increases

A cooking thermometer helps. Without one, dip your finger: "hot but bearable for a few seconds" is a rough guide.

Serving ideas

• Warm: Heat gently in a pot. The simplest way. Add grated ginger for extra warmth
• Chilled: Refrigerate for a refreshing drink, great for HCMC's heat
• Smoothie: Blend with banana or frozen fruit for naturally sweet, sugar-free smoothie
• As cooking sweetener: Use instead of sugar in simmered dishes and dressings

Storage

• Refrigerated: In a clean container, consume within 1 week
• Frozen: Portion and freeze for about 1 month. Thaw in fridge or warm on stove
• Pasteurized: Briefly heating (just below boiling) stops enzyme activity, stabilizing flavor. But enzymes are deactivated, so drink fresh if you want live enzymes

Amazake in HCMC

HCMC's heat requires extra temperature attention, but working in an air-conditioned room solves this. Experience Japanese fermentation culture through homemade amazake.

Cold amazake smoothies are a wonderful energy boost on hot days. Safe for children too.

Download the Farmi app and find rice koji for making amazake.

Note: This article and some images were created with the assistance of AI (artificial intelligence) and reviewed by the editorial team before publication.