The Danish version/Den danske version
Blue gin or vodka – how to make the magical, colour-changing spirit
I’ve been experimenting with blue gin and vodka for many years.
There’s something fascinating – almost magical – about a blue spirit that changes colour when you add lemon, lime, or tonic.
And I’ve tried it all: infusions that are too long, too many flowers, bitter flavours, and a greyish sediment.
But blue gin and vodka are some of the most satisfying spirits to make – once you find the right balance.
It doesn’t require advanced equipment or special skills – just a short infusion time, precise dosage, and thorough filtration.
The result?
A colour-changing spirit that always impresses in cocktails – and adds a fun blue element to your next lunch with family and friends.
Here you’ll find my well-tested recipe, tips to avoid the most common mistakes – and free labels so you can keep the bottle or give it away as a gift.
Contents – click here – and jump directly to what you’re interested in
- Blue infusion
- What is butterfly pea?
- Colourants in butterfly pea: Ternatin and flavonoids
- The typical beginner mistakes – and how to avoid them
- The damaging light
- How your gin affects the colour
- How the alcohol protects – and interferes with – the colour
- Where can you buy butterfly pea flowers?
- How to use your blue alcohol
- Print free Butterfly Pea labels
- The recipe: how to make blue gin or vodka
- Have you also made blue alcohol?
Blue infusion
Butterfly pea in alcohol is one of the great infusions; it’s easy to make, requires only a short steeping time, can be made year-round, and has an undeniable wow factor.
If you’re new to the world of alcohol infusions, I walk you through every step.
If you’re experienced and have created plenty of infused spirits, you can jump right in.
This is a 100% natural blue alcohol infusion made from just two ingredients – alcohol and butterfly pea.
I initially used butterfly pea powder; it gives good colour quickly, but is incredibly tricky to filter.
Now I use whole dried butterfly pea flowers; they also infuse quickly, give you blue alcohol within 2–3 hours, and are easy to strain out – a big plus in my book.
So, have a browse online – see Where can you buy butterfly pea flowers?, visit your local liquor store, and get ready to impress your guests when you create stunning colour-changing cocktails – or blue schnapps for your Christmas table.
What is butterfly pea?
Butterfly pea (Clitoria ternatea) is a tropical climbing plant from Southeast Asia with intense blue flowers.
They are used in food, tea – and here: to make the most spectacular colour-changing spirit (1).
The flower contains natural colourants, anthocyanins, that react to pH value (2,3) – so the cocktail can be blue, purple, or pink, depending on what you add.
But why does the infusion turn blue?
Colourants in butterfly pea: Ternatin and flavonoids
Just as in the post about Lilac Syrup with beautiful colour and good flavour, where I examined the dramatic colour changes of anthocyanins, I have also studied the colour shifts in butterfly pea flowers.
Butterfly pea contains different anthocyanins to, for example, lilacs and roses.
The flower contains a special natural pigment called ternatin, which is more light‑stable than the pigments found in blueberries, for instance (4).
This is why lavender vodka – which is coloured with blueberries – fades so quickly.
There are also flavonoids in the flower, which help keep the colour clear and prevent it from fading (2,3) – making them the perfect partners for ternatin in our blue spirit.
All this makes your butterfly pea spirit the ultimate pH indicator.
- In neutral spirits – such as vodka – the colour is blue, producing the most stunning cobalt blue vodka.
- Gin may range from cobalt blue to blue‑purple, depending on infusion time and the botanicals used.
The magic happens when you add acid.
Add a little and the colour becomes purple; the more acid you add, the pinker it gets.
I recommend adding the acid only when you make drinks – not to the bottle itself.
If you add an alkaline ingredient such as bicarbonate of soda, the colour will shift to green – and later yellow, as pH rises.
I don’t recommend trying this, as alkaline drinks taste soapy and bitter.
The chemistry behind the colour change – click to see
Butterfly pea primarily contains ternatins – polyacylated delphinidin‑anthocyanins (4).
Polyacylated delphinidins are a type of anthocyanin – the pigments responsible for many blue, purple, and red colours in plants.
The fact that ternatins are “polyacylated” makes the colour far more light‑stable.
The many aromatic acyl groups — chemical groups with a ring‑shaped structure — fold around the anthocyanin core, forming a protective “shell”.
This intramolecular stacking provides an unusually stable, intense blue colour at a slightly neutral pH.
Together with the flower’s natural flavonoids (2,3), colour strength can be enhanced through co‑pigmentation, but crucial stability comes from acylation.
This is why you get a stronger, more light‑stable blue than with, for example, blueberries, which mainly contain non‑acylated anthocyanins.
Why does the colour change?
The change occurs because the ternatin anthocyanins are sensitive to pH (2,3).
When pH changes, the molecule’s shape changes – and each form absorbs light differently.
And this gives different colours:
- In an acidic solution (low pH): The molecule exists in its most stable form, flavylium → reddish to purple hues.
- In a neutral to slightly basic solution: The structure changes to quinonoid forms, which absorb more blue light → an intense blue.
In ternatins, this form is particularly well stabilised by the aromatic acyl groups and flavonoids, preventing the colour from fading. - In a highly basic solution (very high pH): The anthocyanin ring can open to form chalcone forms → green‑yellow shades.
This form is unsuitable for cocktails, as alkaline drinks taste soapy and bitter.
It’s the exact mechanism that makes red cabbage change from red → purple → blue, but because ternatins are polyacylated, they are both more light‑ and pH‑stable.
This is why butterfly pea can maintain a clean, intense blue, whereas blueberries or red cabbage, for example, fade much more quickly.
The typical beginner mistakes – and how to avoid them
Initially, I thought: plenty of butterfly pea powder + a long infusion time = an amazing colour – but I was wrong.
I let my infusion steep for a VERY long time – as I was used to doing when infusing alcohol with fruit and berries.
But you must NOT do that here.
My infused spirit turned dark – I mean, REALLY dark blue‑purple – with a grey sediment from the flowers.
It didn’t become that beautiful cobalt blue you get when following my optimised recipe.
Below, I answer:
- Why “just a little longer” is the most dangerous thought during infusion time
- Why more flowers don’t create more wow
Why “just a little longer” is the most dangerous thought during infusion time
I have already made all the mistakes, so you don’t have to – here are my tips:
How long should the alcohol infuse?
The blue colour from the ternatins is highly soluble and only requires a short steep to be released.
If you let your alcohol infuse for too long, you risk the flavour turning bitter and the colour becoming cloudy.
And that’s why “just a little longer” is the most dangerous thought during infusion time:
- Let the flowers steep for just a couple of hours.
You rarely need more than 2–3 hours, sometimes only 1½. - Keep an eye on the colour – once your alcohol reaches the desired shade, it’s time to remove the flowers.
The first time you make blue gin or vodka, it’s best to produce small batches and experiment with the infusion time.
Note your results in the “Own notes” section of the recipe so you have them for next time – and feel free to share them in a comment.
Bitterness
The bitter flavour comes from tannins – familiar from red wine and black tea – and too many tannins give a harsh taste.
If you’ve ever brewed a cup of Earl Grey (or another black tea), forgotten about it, and left it steeping far too long, you’ll recognise the same bitterness.
Cloudiness
Over‑steeping can also extract compounds that cloud the colour, and cause the flowers to start breaking down, releasing tiny particles that make your gin or vodka murky.
It is important to strain your gin or vodka thoroughly once infusion is complete, leaving no petals or “flower dust” behind.
If you use butterfly pea powder, you’ll need to filter several times, as paper coffee filters clog quickly – I prefer a metal coffee filter, which can be rinsed and reused.
If you do use paper filters, wet them first with a bit of alcohol so they absorb that rather than your blue infusion.
For me, removing all the fine particles from butterfly pea powder is tricky, which is why I now use whole dried flowers.
Why more flowers don’t create more wow
In the recipe, I use 1.25 g of dried butterfly pea flowers.
If you have a digital scale that measures to 0.1 g, it can be tricky to hit that exactly.
The recipe is tested at 1.25 g – so aim for 1.2–1.3 g, which in practice can range from 1.15–1.34 g as the scale rounds.
Anything between 1.2–1.3 g yields the same result – if you are precise.
More flowers do not necessarily mean more vibrant colour or greater wow‑factor.
Why not?
Ternatin is so soluble that even a small quantity can saturate the alcohol with blue pigment.
Adding more flowers risks producing a darker, duller shade, or even one with a grey cast – as I found with my first infusions.
Extra flowers also release more tannins and fine particles, potentially making the alcohol bitter and cloudy.
Therefore, there’s no need to exceed the recommended amount – the infusion time is already short, and the alcohol quickly reaches its optimal clear colour.
If you want to experiment with more flowers, reduce the steeping time, as the saturation point will be reached faster.
The damaging light
Ternatin works together with flavonoids, making them more light‑stable than many other anthocyanins.
However, the blue can still fade or shift if your infused alcohol is left exposed to sunlight.
You can reduce the risk by bottling in dark glass – though you then lose sight of that stunning cobalt.
Alternatively, use clear bottles but store them in a cool, dark place when not serving cocktails.
If your blue vodka is to be enjoyed as schnapps, use a clear bottle, and keep it in the freezer.
How your gin affects the colour
Gin varies – especially in the botanicals that give it flavour.
Some enhance the blue, while others alter pH and can make the spirit darker or more bitter.
Main factors affecting colour:
- Acidic botanicals such as citrus peel lower pH → blue to purple (2). Lemon peel is a frequent culprit.
- Alkaline ingredients such as liquorice root may raise pH → blue to green (very rare).
- Phenols and tannins from roots, seeds, or bark may dull colour and add bitterness.
- Distillation method – determines how many flavour compounds carry over into the gin.
- Alcohol strength – higher proof stabilises the colour more effectively.
Tip:
- Choose a classic, neutral gin → clear blue.
- Opt for a gin with strong citrus notes → expect purple tones from the start.
How the alcohol protects – and interferes with – the colour
Alcohol can influence your infusion in several ways:
Alcohol preserves – the stronger the alcohol, the more effectively it inhibits microbial growth.
Microorganisms, if present, can break down pigment molecules and cause fading (3).
Alcohol stabilises and protects the colour – it stabilises the ternatin molecule (4), helping your gin or vodka retain that glorious hue for longer – if stored correctly (1), see The damaging light.
Alcohol can also interfere – it may extract acids or other compounds from botanicals, shifting the pH and interacting with anthocyanins (2,3) – see also Why “just a little longer” is the most dangerous thought during infusion time.
Where can you buy butterfly pea flowers?
I buy my dried butterfly pea flowers and powder online.
Search for “dried butterfly pea flowers buy” or “butterfly pea powder buy” – without quotation marks.
Choose organic where possible to avoid pesticide residues in your infusion.
- Dried butterfly pea flowers (Clitoria ternatea) – also sold as Butterfly Pea, (and in Danish Sommerfugle‑ærteblomster).
- Butterfly pea powder (pulverised flowers) – also labelled Butterfly Pea Flower Powder.
How to use your blue alcohol
Blue gin and vodka are proper show‑stoppers!
These are spirits best showcased in cocktails prepared in front of your guests – so they can witness the magic happen.
With blue gin or vodka, there’s little point in making up a pitcher ahead of time – unless you’re only after purple drinks.
For a party:
- Make a gin and tonic – and watch the colour transform in the glass.
- Use blue alcohol in a classic sour and add lemon at the table – instant wow‑factor.
- Create a lemonade spritz – shifting from blue to a delicate old‑rose hue.
- Or why not a Moscow Mule? – Serve in a clear glass so the transformation is visible.
Who says you have to mix cocktails? …when you can serve a small glass of pure magic.
Offer the blue vodka neat as schnapps for Sunday lunch, Christmas, Easter, a party…
For extra wow‑factor, keep a little lemon juice in a pipette, spray bottle or similar, so guests can add a few drops and watch their schnapps transform before their eyes.
Give your blue gin or vodka as a gift
- Pour 200 ml into a small bottle, add your own label, and present it as a hostess gift.
- Pair it with miniature bottles of tonic and syrup to create a mini cocktail kit.
Print free butterfly pea labels
I’ve designed several butterfly pea labels in various sizes and styles.
Choose the designs you like best – and that best suit the shape of your bottles and any gifts.
Print the labels on standard A4 copy paper (80–120 g/m²).
Cut them out with scissors or use a craft knife – a ruler and cutting mat help with straight edges.
The round labels are ideal for bottle caps or as decoration on cards and packaging; for best results, use a punch of approx. 2.5 cm or 3.5 cm in diameter.
There is no date or year printed on the labels; I recommend writing that on yourself.
You can make as many labels as you like.
It is free for you as a private individual to use the prints, instructions and templates that I post on Danish Things.
I hold the copyright to all content on Danish Things and associated social media.
Read more about copyright and use of materials from Danish Things here, where you can also find information about reporting to Copydan Tekst & Node / VISDA.
If you download the materials directly from Danish Things each year, you support my work, enabling me to develop new prints and templates.
To save the link, you can add a Pin so you can find the recipe and labels again next year – or discover other recipes with matching labels.
The recipe: how to make blue gin or vodka
Now it’s time to work your magic!
Create blue gin or vodka that changes colour, making your guests exclaim, “Hey – what’s happening there?”
A short steep, the right amount of flowers, and a few simple tricks – and you’re there.
Ready?
Below you’ll find my optimal mixing ratio — in just a couple of hours — you’ll have your own magical spirit.
Magical Butterfly Pea Alcohol – Blue Gin or Vodka
Equipment
- Digital kitchen scale - that can display decimals
- Large preserving jar with lid or Kilner jar – scalded and cooled
- Metal sieve
- Coffee filter (metal or paper) – or a piece of fine‑meshed fabric
- Funnel – scalded and cooled
- Glass bottles with airtight lids – scalded and cooled (if you’re reusing the original alcohol bottle, no need to scald)
- labels – optional
Ingredients
Blue Gin or Vodka with Butterfly Pea
- 665 g 40 % alcohol – e.g. Beefeater Gin or Absolut Vodka – choose a neutral spirit you enjoy the taste of
- 1.25 g dried butterfly pea flowers
Instructions
Preparation
- Scald and cool your large preserving jar and the funnel for later. If using the alcohol’s original bottle, there’s no need to scald it – but if using other bottles, scald them now so they have time to cool.
Weigh your alcohol
- Place the cooled jar on your scale and reset to zero. Pour in your gin or vodka and weigh. Note: 70 cl spirit typically weighs between 664 g and 667 g, depending on ABV.
Find the amount of flowers
- Use the plugin to calculate how many grams of dried butterfly pea flowers you need based on your spirit’s weight. For 70 cl of 40 % alcohol, you’ll need 1.2–1.3 g – more isn’t necessarily better (see main text).
Infusion
- Add the flowers to the alcohol, sealing the lid tightly. Invert the jar gently a couple of times. Leave the alcohol and flowers to infuse at room temperature – preferably out of direct sunlight.
Steeping time
- Infuse for approx. 2–2½ hours at room temperature. - Gin contains more botanicals than vodka, so it will start developing a dark blue‑purple tone after around 2½ hours. - Vodka, being purer, stays bright blue for longer – you can leave it up to 3 hours.
Important
- Do not over‑steep. Watch the colour as it develops – when it’s as deep blue as you want, it’s time to strain, even if only 1½–2 hours have passed. A more prolonged infusion won’t improve the colour; instead, it can turn it a dark blue‑purple and add slight bitterness from the tannins in the petals.
Straining
- Place the scalded, cooled funnel into a suitable bottle (dark glass if possible). Fit a (metal) coffee filter into the funnel and position a sieve above it to catch the petals. It’s quicker if only the infused spirit passes through the filter.
- Tip: Moisten the filter first with a bit of alcohol so it doesn’t absorb as much of your blue gin or vodka.
Label your bottle
- Add a label so you know exactly what’s inside.
Storage
- Store your blue gin or vodka in a cool, dark place to best preserve the colour.
Notes
If you use US customary units, remember that the recipe is made using Metric and converted via a plugin.
Private notes
Show me your blue drinks!
Have you tried making blue gin or vodka?
Share your photos and experiences – tag @danish_things or use #danishthings on Instagram.
And leave a comment below – I’d love to see what you’ve created.
Share your blue drink moments with #danishthings ✨
Sources – click to see
- Fu X, Li X, Fan X, He X, Cai H. Spectral characteristics, storage stability and antioxidant properties of anthocyanin extracts from flowers of Butterfly Pea (Clitoria ternatea L.). Molecules. 2021;26(15):4693. doi:10.3390/molecules26154693
- Yoshida K, Mori M, Kondo T. Blue flower colour development by anthocyanins: from chemical structure to cell physiology. Nat Prod Rep. 2009;26(7):884‑915. doi:10.1039/B800165K
- Castañeda‑Ovando A, Pacheco‑Hernández ML, Páez‑Hernández ME, Rodríguez JA, Galán‑Vidal CA. Chemical studies of anthocyanins: A review. Food Chem. 2009;113(4):859‑871. doi:10.1016/j.foodchem.2008.09.001
- Kazuma K, Noda N, Suzuki M. Flavonoid composition related to petal colour in different lines of Clitoria ternatea. Phytochemistry. 2003;64(6):1133‑1139. doi:10.1016/S0031-9422(03)00419-8