Butterfly Pea Flower Extract Recipe: How to Make It for Thai Food and Drinks

To make butterfly pea flower extract, steep dried or fresh butterfly pea flowers in hot water until the liquid turns deep blue, then strain out the petals. A practical starting point is a small handful of dried flowers, roughly 10–20, in about 250 ml of water just off the boil, steeped for 5–10 minutes. Adjust the amount by eye until the color is as strong as you want. The result is a vivid, almost inky blue liquid with a mild, earthy taste. Thai cooks use it to color drinks, rice and desserts. Add lime or another acid and the blue turns purple, then pink. That color change is the extract's best-known trick.

What Is Butterfly Pea Flower Extract?

Butterfly pea flower extract is a water infusion made from the petals of the butterfly pea vine (Clitoria ternatea), known in Thai as dok anchan. It works mainly as a natural coloring, not a flavoring. Its taste is gentle: slightly grassy, woody and hay-like, somewhat like a very light green tea. On its own it is neither sweet nor sour, so it takes on the character of whatever it is mixed with.

The blue comes from anthocyanins, the same family of plant pigments found in red cabbage and blueberries. These pigments dissolve readily in water. That is why simple steeping is enough and no special equipment or alcohol is needed.

How to Recognize Dried and Fresh Butterfly Pea Flowers

Butterfly pea flowers have a distinctive shape. Each bloom has one large, rounded, slightly ruffled petal in deep cobalt or royal blue. The center is pale white to yellowish and is often described as eye-shaped. A small green, cup-like base (the calyx) holds the flower to the stem.

Dried butterfly pea flowers

Dried butterfly pea flowers are sold in bags at Asian grocery stores and tea shops. They look crumpled and papery, with dark indigo to violet-blue petals and pale centers. Good-quality dried flowers keep a strong blue color and smell faintly of hay. Flowers that look grayish or brownish, or that smell dusty or musty, will usually give a weaker, duller extract.

Fresh butterfly pea flowers

Fresh butterfly pea flowers grow on a climbing vine common in Thai gardens and on fences. They are soft and bright blue, and the vine also produces flat green pods. Fresh flowers give a lighter, more delicate extract than the same number of dried flowers, because their pigment is diluted by the water still in the petals. Many cooks pinch off the green base before steeping, since it can add a grassier taste and a slight greenish tint.

Feature	Dried butterfly pea flowers	Fresh butterfly pea flowers
Appearance	Crumpled, papery, deep indigo-blue	Soft, smooth, bright cobalt blue
Where to find	Asian grocers, tea shops, online	Home gardens and markets in tropical regions
Color strength per flower	Stronger, more concentrated	Lighter; you need more flowers
Preparation	Use as is; a quick rinse is optional	Rinse gently; remove the green base if you like
Shelf life	Many months in a dry, airtight, dark container	Best used within a day or two of picking

Basic Butterfly Pea Flower Extract Recipe

This butterfly pea flower extract recipe uses hot water and dried flowers. It is the most common home method and works for drinks, rice and desserts.

What you need

Dried butterfly pea flowers: about 10–20 flowers per 250 ml of water as a starting point, or roughly double that if using fresh flowers
Water just off the boil
A heatproof jar, teapot or small saucepan
A fine-mesh strainer, cheesecloth, or a Thai cloth tea filter (the sock-like strainer used for Thai iced tea)
A clean glass jar or bottle for storage

Steps

Prepare the flowers. Place the dried flowers in the jar or pot. If using fresh flowers, rinse them gently and pinch off the green bases first.
Add hot water. Pour water that has just stopped boiling over the flowers. Within seconds the water starts turning blue.
Steep. Leave the flowers for about 5–10 minutes. Stir or press them gently with a spoon once or twice to release more color.
Check the color. Hold the jar up to the light. For a soft sky blue, stop early. For a deep, almost navy blue, steep longer or add more flowers.
Strain. Pour the liquid through the strainer or cloth and press lightly on the petals. The spent flowers will look pale and washed out.
Cool and store. Let the extract cool, then pour it into a clean, sealed container and refrigerate.

Keep the extract plain if you want it to stay blue. Add lime juice, sugar syrup or other flavors only when you use it.

The Butterfly Pea Flower Extraction Process Explained

The butterfly pea flower extraction process has three stages: steeping, which draws pigment into the water; straining, which removes the plant material; and, optionally, concentration, which makes the color stronger. Understanding each stage helps you control the color and taste.

Steeping: hot or cold

Steeping means soaking the flowers in water so the pigment dissolves out of the petals. Hot steeping works in minutes and gives the most intense color quickly. Cold steeping means leaving the flowers in cold water in the refrigerator for several hours or overnight. It is slower but gives a clean, mild-tasting extract that is convenient for iced drinks. Very long hot steeping or hard boiling can bring out more of the woody, grassy flavor. Heat and light also gradually weaken anthocyanin pigments, so gentle treatment keeps the blue brighter.

Straining

Straining separates the liquid from the petals. A fine-mesh sieve is enough for drinks. For clear desserts or jellies, line the sieve with cheesecloth or use a cloth tea filter to catch small petal fragments. Pressing the petals lightly gets out the last of the color. Squeezing them hard can make the extract cloudier.

Concentration

Concentration refers to how strong the color is in a given amount of liquid. Strength matters because recipes such as rice or dough need intense color without adding too much water. You can raise the concentration in three ways:

Use more flowers in less water. This is the simplest method and the gentlest on the color.
Re-steep fresh flowers in an existing extract. This builds up color without heating the liquid for long.
Simmer gently to reduce. This works, but prolonged heat can dull the blue and deepen the earthy taste, so keep it short and low.

A light extract suits drinks. A strong, dark extract suits coloring rice, sticky rice and doughs, where the color is diluted by other ingredients.

Why Does Butterfly Pea Extract Change Color?

Butterfly pea extract changes color because its anthocyanin pigments react to acidity (pH). In plain water the extract is blue. When you add an acid such as lime juice, lemon juice or tamarind water, it shifts to violet, then purple, then magenta-pink as acidity increases. In alkaline conditions, for example with a pinch of baking soda, it can drift toward a greenish blue, but this also affects taste.

This reaction explains why some dishes made with the extract come out purple instead of blue. It also explains why the classic Thai drink is often served blue with a wedge of lime on the side. The color changes in front of the person drinking it.

How Thai Cooks Use Butterfly Pea Flower Extract

In Thai cooking, butterfly pea extract is used mainly to add color, often alongside pandan for green and coconut milk for richness. Familiar examples include:

Nam dok anchan (butterfly pea drink): The blue extract is sweetened with syrup or honey and served over ice with lime. It turns purple when the lime is stirred in. Lemongrass is sometimes added for fragrance.
Blue rice and sticky rice: Cooks replace some or all of the cooking or soaking water with extract. The grains turn soft blue to lavender. Blue sticky rice is often served with mango and coconut sauce.
Khanom chan (layered dessert): This chewy, steamed dessert is made of thin layers of flour, coconut milk and sugar. Butterfly pea extract colors some of the layers blue or purple.
Chor muang: These delicate, flower-shaped steamed dumplings are traditionally tinted purple with butterfly pea.
Jellies and ice cubes: Extract set with agar or frozen into cubes makes colorful additions to drinks and desserts.

Simple tips for cooking with the extract

Add acid last if you want the dish to stay blue. Even a little lime can turn it purple.
Coconut milk softens deep blue into a pastel blue or lilac.
For layered drinks, pour the blue extract slowly over ice on top of a denser, sweetened or juice layer. The layers stay separate until stirred.

How It Differs from Other Blue and Purple Colorings

Butterfly pea extract is not the only natural way to get blue or purple food, but it behaves differently from the alternatives. The table compares common options.

Coloring	Color	Flavor	Reacts to acid?	Typical use
Butterfly pea flower extract	Blue, turning purple to pink	Mild, earthy, tea-like	Yes, strongly	Thai drinks, rice, desserts
Blue spirulina powder	Bright turquoise-blue	Mostly neutral	No, it stays blue	Smoothies, frostings, uncooked foods
Purple sweet potato or ube	Purple	Sweet, starchy, nutty	Only slightly	Desserts, baked goods; adds body, not just color
Red cabbage water	Purple-blue, pH-sensitive	Noticeable cabbage taste	Yes	Mostly a kitchen science demonstration
Artificial blue food coloring	Stable blue	None	No	Baking and candy

Substitutes and Their Limitations

If you cannot find butterfly pea flowers, a few substitutes can stand in, but none behaves the same way.

Butterfly pea powder: This is the closest substitute. It is made from ground flowers and dissolves straight into liquid, but it can leave fine sediment and taste slightly more vegetal.
Butterfly pea tea bags: These are convenient for drinks. They often contain fewer flowers, so the color may be lighter.
Blue spirulina: It gives a strong blue but will not turn purple with lime, so the signature color-change effect is lost.
Purple sweet potato: It gives purple color to rice and desserts but adds starch and sweetness, and it cannot give a true blue.

How to Store Butterfly Pea Flower Extract

Store homemade butterfly pea flower extract in a clean, sealed glass container in the refrigerator, away from light, and use it within a few days. Because it is a plain water infusion with no preservatives, it can spoil like any fresh brewed tea. Throw it out if it smells sour, turns cloudy or develops a film. The color also fades and can dull toward gray-blue as it ages. For longer storage, freeze the extract in ice cube trays and drop the cubes into drinks or thaw them for cooking.

Common Problems and Quick Fixes

The color is pale: Use more flowers, less water or a longer steep, or re-steep with fresh flowers.
It turned purple unexpectedly: Something acidic was added. This includes citrus, some fruit juices and tamarind. Keep acidic ingredients separate until serving.
It tastes grassy or bitter: Shorten the steeping time, avoid hard boiling, and remove the green bases from fresh flowers.
It looks cloudy or has bits in it: Strain again through cheesecloth or a cloth tea filter.