Ama Koji (Sweet Koji): The Perfect All-Natural Sugar Substitute

15

Ama Koji (甘麹) is a concentrated form of amazake made by fermenting rice koji with water (and optionally cooked rice). Without a single grain of added sugar, the natural enzymes in the koji break down the rice starches into glucose, creating an incredibly rich, intense natural sweetness.

It makes a fantastic, healthy substitute for sugar in cooking and baking, and it is packed with beauty and wellness benefits!

Features & Benefits of Ama Koji

• Sugar Substitute: Use it in place of sugar for cooking, baking, or desserts. As a general rule, replace sugar with 2 to 3 times the amount of Ama Koji for a refined, deeply flavorful sweetness.
• Health & Beauty: Rich in oligosaccharides and dietary fiber to improve gut health, as well as B vitamins and amino acids to help recover from fatigue.
• Easy Drink: Simply dilute it with 2 to 3 parts water, warm water, or soy milk to enjoy as a delicious, comforting Amazake drink.

Below are two methods to make Ama Koji: Without Rice (purer flavor) and With Rice (sweeter and more economical).

Ama Koji vs. Amazake: What’s the Difference?

f you are familiar with Japanese fermented foods, you might be wondering: Is Ama Koji the same thing as Amazake? Technically, yes! They share the same roots, but they are used differently. Think of Ama Koji as the “base concentrate” and Amazake as the finished drink.

• Ama Koji (甘麹): A thick, rich paste made by fermenting rice koji with minimal water. It acts as a living, unrefined sugar substitute for cooking and baking (or a healthy topping for yogurt!).
  
• Amazake (甘酒): A smooth, comforting beverage. When you dilute Ama Koji with water, milk, or soy milk, it instantly becomes Amazake. It’s essentially “drinkable Ama Koji.”

Quick Comparison: How to Use Them

Feature	Ama Koji (甘麹)	Amazake (甘酒)
Texture	Thick, rich paste	Smooth, liquid drink
Main Use	Sugar alternative for cooking, baking, marinades, or mixing into yogurt.	A nutritious, sweet beverage enjoyed hot or chilled.
How to Make It	The concentrated starter recipe is found below.	1 part Ama Koji diluted with 2 to 3 parts water or milk.

How to Make Ama Koji

Yield

With-Rice Method: Approx. 310 ml ( 13 oz )

Without-Rice Method: Approx. 380 ml (10.5 oz)

Ingredients

Option A: Ama Koji (Without Rice)

• Dried Rice Koji: 200g
• Water (or Warm Water): 350ml – 400ml

Option B: Ama Koji (With Rice)

• Dried Rice Koji: 100g
• Cooked Rice: 130g
• Water: 130ml – 160ml

Step-by-Step Instructions

1. Sterilize the Equipment (Crucial Step)

Sterilize your containers and mixing utensils with boiling water, then let them air dry completely.

2. Mix the Ingredients

• For the Without-Rice Method: Break up any clumps in the dried rice koji. Thoroughly mix the koji with water (or warm water at around 60°C / 140°F) in your container.
  
• For the With-Rice Method: First, mix the cooked rice and water together. Then, break up any clumps in the rice koji, add it to the mixture, and stir very well.

3. Fermentation Process

Ferment the mixture at 60°C (140°F) for 6 to 8 hours. You can use an oven with a low-temperature/fermentation setting, a yogurt maker, or a rice cooker.

• Using a Rice Cooker / Yogurt Maker: Put the mixture into the rice cooker inner pot. Leave the rice cooker lid completely open, cover the top with a clean, damp kitchen cloth or paper towel, and set it to the “Keep Warm” (保温) mode for 6 to 8 hours. (If using a yogurt maker, simply set it to 60°C).

4. Midway Stirring

After about 1.5 to 2 hours of fermenting, open it up and give it a thorough stir, flattening the surface afterwards.

5. Adjust the Moisture

Different brands of rice koji absorb water differently. If the mixture looks too dry or thick at the 2-hour mark, feel free to stir in a small amount of extra water.

6. Completion & Storage

Once the 6–8 hours are up and the mixture is sweet, let it cool down to room temperature. Transfer to clean jars and store.

Chef’s Tip: Blend the finished Ama Koji with a hand blender until perfectly smooth. It makes it much easier to measure and mix into recipes!

Refrigerator: Best consumed within 2 weeks.

Freezer: Can be frozen for up to 3 to 4 weeks.

💡 The Golden Rule of Temperature

The absolute secret to making delicious Ama Koji is maintaining a slow fermentation between 50°C and 60°C (122°F–140°F). Proper temperature management is crucial:

• Below 40°C (104°F): The sweetening process (saccharification) slows down drastically, extending the fermentation time and causing the mixture to easily become sour.
• Around 30°C (86°F): The mixture will develop a yogurt-like sourness, leaving an unpleasant tart taste in the finished product.
• Above 70°C (158°F): The vital koji enzymes will permanently deactivate, and it won’t become sweet at all.

To get the sweetest, most delicious result, always keep the mixture at its optimal temperature range to ensure the enzymes can fully break down the starch into glucose!

How to Use Ama Koji

• In Cooking/Baking: Substitute 1 part sugar with 2 to 3 parts of Ama Koji.
  
• As a Drink: Mix 1 part Ama Koji with 2 to 3 parts of water, hot water, unsweetened soy milk, unsweetened almond milk, or regular milk. Enjoy hot or cold!

🛒 Where to Buy Dried Rice Koji

If you are new to making ferments at home, you can easily find high-quality dried rice koji (乾燥米麹) online. Here are a few trusted sources:

• For Artisan Quality: If you want a truly premium flavor profile, I highly recommend checking out the Premium Dry Malted Rice from The Rice Factory New York. Sourced from historic Japanese breweries (like Hattori Jozo), it delivers an incredibly clean, deep sweetness that elevates your ferments.
  
• For Easy Pan-Asian Grocery Delivery: If you use the popular online Asian grocery shop, Weee!, you can pick up the highly reliable Iseso Miyako Koji on Weee!. This traditional block-style koji is a staple in many Japanese kitchens.
  
• For Ultimate Convenience: You can also browse a massive selection of brands directly on Amazon. Check out the current options for dry koji on Amazon to find a brand that ships quickly to your door.