How to Make Blue Food Coloring Naturally

Co-authored by Maria Short and Nihal Shetty

Last Updated: November 10, 2022 References

Wondering how to liven up baked treats and other dishes with a bright blue color? Buying artificial blue food coloring is always an option, but you can also make your own homemade food coloring for a healthier, natural alternative. All you need is red cabbage and a bit of baking soda to create blue food coloring for icing, cocktails, art projects, and more. We’ll show you how in this complete guide on how to make blue food coloring.

Ingredients

1 head of red cabbage
8 cups (1.9 L) of water
½ teaspoon (2.4 g) of baking soda

1

Chop the cabbage up into small pieces.

A rough chop of the cabbage allows you to access its rich color. Place an entire head of red cabbage onto a cutting board. Cut off the stem and discard it. Hold the cabbage steady with one hand, and with a large chef’s knife, roughly chop the cabbage into small chunks.^{[1]
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- Don’t worry about being too precise with your cuts, but smaller pieces are better, since you'll be able to get more color from the cabbage.
- Red cabbage contains anthocyanin. These are natural dyes that are a great alternative to artificial colors.^{[2]
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2

Boil the cabbage for 20 minutes.

Boiling the cabbage releases its color into the water. Transfer the cabbage to a large saucepan. Fill this saucepan with enough water to cover the cabbage, which should be about 8 cups (1.9 L). Put on the lid and bring the water to a boil over medium-high heat. When the water comes to a boil, reduce the heat to medium, and continue simmering for 20 minutes.^{[3]
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- As the cabbage boils, the anthocyanin will leach into the water, turning it purple.

3

Strain the cabbage water.

The colored water is the base for your dye, so separate it from the cabbage. Remove the pot from the heat. Place a colander over a large glass or metal mixing bowl. Pour the cabbage and the purple water into the colander. The colander will catch the cabbage, and the purple water will drain into the bowl below.^{[4]
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- As a bonus, you now have a cooked and ready-to-eat cabbage. Set it aside to cool, and then use it in soups, stews, stir fries, and other dishes.^{[5]
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4

Simmer the mixture for 30 minutes to thicken it.

Boiling away excess water creates a more vibrant dye. Pour the collected purple water into a medium saucepan. Bring the water to a boil over high heat, and then reduce the heat to medium-high. Continue simmering the water with the lid off for about 30 minutes to reduce the purple water. Cook the mixture until most of the water has evaporated and there's only ½ cup (118 ml) of liquid left.^{[6]
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- As the liquid cooks, the water will evaporate and the liquid will reduce, leaving behind a more concentrated and more vibrant purple water.

5

Let the mixture cool to room temperature.

Give the mixture a chance to cool off before you experiment with it. When the water has reduced, remove the saucepan from the heat. Set the pan aside to cool to room temperature. This could take another 30 minutes. When the purple concentrate has cooled, pour it into a clean mason jar or other clear container.^{[7]
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6

Pour the dye into a jar and add baking soda.

Add the baking soda in small quantities so you can control the color. Measure ⅛ teaspoon (0.6 g) of baking soda and pour it into the jar with the purple concentrate. Stir the mixture to dissolve the baking soda in the water, and allow the bubbles to subside if necessary.^{[8]
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- Use a clear jar so you can see the color change as you add the baking soda.
- When you mix the anthocyanin with an alkaline ingredient like baking soda, it becomes blue.
- In an acidic environment, the anthocyanin will become redder. You can even make a red dye by adding lemon juice.

7

Use milk and a clear glass to test the color.

A clear glass filled with white liquid shows you how blue your dye is. Measure ¼ cup (59 ml) of a white liquid, such as milk, soy milk, or coconut milk, into a clear glass. You can also test the color on a small amount of frosting before dyeing the entire batch.^{[9]
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- If the color isn’t blue enough for you, continue to stir in a small amount of baking soda, no more than ⅛-teaspoon (0.6-g) at a time. Too much baking soda will affect the taste of your food coloring, so be careful not to overdo it.^{[11]
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8

Use the dye to add color to treats and projects.

This dye provides you with a rich pastel hue. There are all kinds of places you can apply this dye, and you can always find your favorite uses for it through experimentation. We’ve got some great suggestions for you here if you’re looking for a place to start:^{[12]
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- Blue frosting: Make a batch of vanilla buttercream or your favorite white frosting. Before icing your treats, add several drops of food coloring and stir to combine. If you want a richer blue, take a portion of the buttercream and microwave it with the food coloring, then mix it with the rest.
- Blue ice cream: Homemade ice cream is a fun and tasty project. Transfer the ice cream base to the ice cream maker, turn on the machine, and add the blue food coloring a few drops at a time until you achieve the desired intensity. You can also use this dye in store-bought ice cream.
- Blue Easter eggs: Dyeing eggs is a fun tradition to celebrate Easter. Hard boil the eggs first to help prevent cracking, and when the eggs are dry, dip them into a jar of the blue food coloring for several minutes.

9

Refrigerate leftover dye in an airtight container.

Try to use natural food coloring right away, but leftovers will keep for 2 days. If you have any leftover blue food coloring, transfer it to an airtight container and keep it chilled in the refrigerator. The food coloring will last for a couple of days, but it’s generally best to use this food coloring the same day you make it.^{[13]
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Community Q&A

Question

Will the food coloring make food taste unpleasant?

Qamar

Top Answerer

Dye is collected from the purple cabbage, so it doesn't have much of a flavor to it. It's mostly a coloring tool that can change the appearance of your food.
Question

can we add the some food coloring to edible condensed milk slime.

Nihal Shetty

Community Answer

Definitely! This food coloring would work great with condensed milk. Enjoy using it!