What is Kuromitsu?
Kuromitsu (黒蜜) is a Japanese sugar syrup that when translated directly, means “black honey”. It is made with “kokuto” (黒糖), an unrefined dark brown sugar and specialty product of Okinawa and Kagoshima prefecture. Kokuto (also known as kurozato or “black sugar”) is made purely from the extracted juices of sugarcane, which is then cooked slowly over low heat to remove impurities.
Although it is visually similar to molasses, it has a lower viscosity and milder flavor. It is well-loved for its rich and slightly bitter taste and is often poured over Japanese sweets (wagashi) such as warabi mochi and anmitsu. It’s also popular to use in drinks such as bubble tea, iced lattes and milkshakes.
I’ve made small batches of kuromitsu many times for other recipes, so this time I wanted to share how to make a slightly larger batch that can be kept in the fridge. It’s really easy and only requires 3 ingredients!
Key Ingredients & Substitution Ideas
- Dark brown sugar: The key ingredient for this recipe is dark brown sugar. Although Okinawan brown sugar (kokuto/kurozato) is commonly used to make it in Japan, dark muscovado sugar works perfectly well.
- White sugar: Using dark brown sugar alone will produce a kuromitsu that is quite bitter. To balance the sweetness, I find adding white sugar makes the syrup more delicious. I use a 50/50 ratio, but you can adjust the ratio to suit your preference. I used caster sugar, but granulated is fine too.
- Water: I use a basic 1:1 ratio and then reduce it down a little for a syrup slightly thicker than simple syrup.
Visual Walkthrough & Tips
Here are my step-by-step instructions for how to make homemade Japanese kuromitsu. For ingredient quantities and simplified instructions, scroll down for the Printable Recipe Card below.
This section aims to provide a comprehensive overview of the cooking steps and techniques with visuals. It also includes more in-depth tips and tricks and explains why I do what I do.
STEP
Add the ingredients to a pan
Measure your sugars and water and place them in a cold pan. Mix them well and break up any large lumps of sugar before you move the pan to the stovetop.
Heat on medium and continue to stir the mixture until it starts to bubble. Once it’s gently bubbling, reduce the heat to medium-low and simmer until all of the sugar has dissolved and the mixture has thickened slightly.
If foam forms around the edges, scoop it out with a spoon for a clearer end result.
How thick should it be?
Keep in mind that syrup will thicken when it cools. I usually simmer until the syrup coats a thin layer over a spoon. If the syrup is too thin after cooling, you can reduce it more by returning it to the saucepan and simmering over low heat.
Remove the pan from the heat and let the syrup cool before using or storing.
To store, transfer it to a clean airtight container (I prefer to use glass) and keep it in the fridge.
Enjoy your homemade kuromitsu in drinks and pour over your favorite Japanese sweets!
Storage
For best results, store in a clean sterilized glass container with an airtight lid in the fridge. When properly stored, you can keep this kuromitsu in the fridge for up to 4 weeks.
Do not store at room temperature.
Syrup with signs of cloudiness, mold growth or a strange odor should be discarded.
Crystallization – Causes and Tips to Prevent It
There are a few reasons why homemade syrups might crystallize. Here are a few tips you can use to prevent or fix it in case it happens.
- If the sugar is not melted completely before it’s taken off the heat, then the remaining sugar crystals can harden and grow more crystals as it cools. To prevent this, make sure the sugar is completely dissolved before cooling.
- If the syrup is cooked for too long, the water will evaporate and throw off the water-to-sugar ratio. If there is not enough water in the syrup, the sugar will harden and crystallize. You can avoid this by reducing the cooking time.
- If the syrup is stored incorrectly and exposed to air for too long, crystallization can occur due to natural evaporation. Once cooled, transfer to a glass container with an airtight lid and store in the refrigerator.
How to Fix Crystallized Syrup
- If the syrup is watery with large crystals, it probably wasn’t fully dissolved. You can fix it by returning the syrup to a pot on the stove and taking care to melt the sugar completely over low heat.
- If the syrup is too thick with some crystallization or solidification, then it was probably heated for too long. In this case, it will probably be stuck inside the container. Remove the lid and heat in the microwave for 20-30-second intervals until you can transfer the contents into a saucepan. Add an equal amount of water and dissolve the crystals. Wash and sterilize the container before pouring the cooled syrup inside – leftover crystals will cause more crystals to form again.
FAQ
Sure, you can return it to the stove and reduce it over low heat until it reaches your desired consistency. Keep in mind that the syrup thickens when it cools, so it will seem thin when cooking.
Yes, you can add more water. Use hot water to help incorporate it into the mixture.
Dark sugar tends to clump and doesn’t dissolve easily, heating it gently on the stove ensures all of the sugar is fully dissolved which helps prevent crystallization.
No, homemade kuromitsu should be kept in an airtight container in the refrigerator.
Kuromitsu is a popular topping for Japanese desserts such as warabi mochi, anmitsu, shiratama dango, and more. It’s also delicious poured over ice cream or used in drinks.
I hope you enjoy this homemade kuromitsu recipe! If you try it out, I’d really appreciate it if you could spare a moment to let me know what you thought by giving a review and star rating in the comments below. It’s also helpful to share any adjustments you made to the recipe with our other readers. Thank you!
Enjoy Kuromitsu With These Recipes
Looking for ideas on where to use your homemade kuromitsu? Try it with these recipes!
Homemade Kuromitsu (Japanese Brown Sugar Syrup)
Kuromitsu is a rich, sweet, and mildly bitter dark brown sugar syrup often served with traditional Japanese sweets. It’s also great for drinks or ice cream!
Ingredients
Prevent your screen from going dark
Notes
Feel free to half, double, or triple using a 1:1 volume ratio of total sugar to water.
