How to make natural blue food coloring with just 2 ingredients: red cabbage and baking soda. Step-by-step guide + VIDEO tutorial + blue smoothie recipe!
The most elusive color in the edible world: blue. Every other component of the rainbow can be created quite easily with veggies and fruits, but blue foods are hard to come by. Well unless you go order a bottle of food coloring gel in the shade royal blue off of Amazon for three dollars, that’s about as easy as it gets. But when an ingredient label has numbers in it, I tend to shy away.
For a while I had heard murmur of using red cabbage + baking soda to create a natural blue food coloring, but it sounded weird and hard and intimidating. Then I got a crazy cake recipe idea that required edible blue and was too fun not to pursue, so cabbage method here I come!
And now that I’ve done it, I have to admit it’s actually not that hard. Not worth procrastinating for this long. A little time consuming, maybe. But not much active time, mostly just watching a pot boil.
I’m sure I’m not the only one who has been yearning for blue smoothies and frostings and puddings without artificial ingredients and that don’t taste like spirulina, so I thought I would make a video tutorial along with step by step instructions showing you how to do it too.
This method for natural blue food coloring uses two of the cheapest ingredients around and makes about 1/2 cup (which will keep in the fridge and go a long way). So a couple of hours now and you’ll have blue food for daysssss.
Natural Blue Food Coloring Step-by-Step
Step 1: Chop up an entire head of red cabbage. It doesn’t have to be finely diced or anything fancy, just roughly chop.
Step 2: Add to a large pot with enough water to cover it. It took about 8 cups of water for me.
Step 3: Boil for 20 mins. Strain out the cabbage. Return the purple water to the pot. (That is A LOT of cabbage you now have on your hands, so make a salad, make a stir-fry, compost it, put it in your pampered pup’s homemade meals–it’s your call.)
Step 4: Reduce this liquid to between 1/3 and 1/2 cup. This will concentrate the color and allow you to use just a teaspoon as opposed to an entire cup of liquid to get the same intensity of color. It took about 1 hour and 15 minutes of boiling for me.
Step 5: Let it cool, then transfer to a glass jar. Glass is important so you can see the color change.
Step 6: Add baking soda 1/8 tsp at a time, stirring in between. If it bubbles up, I suggest letting the bubbles subside before continuing so you can see the true color. Keep adding until the color turns from purple to blue. Try to not exceed 1/2 teaspoon total or it will start to taste metallic and salty.
Step 7: Test the color in a small glass of coconut or almond milk. It’s easier to see the color in something white. If it’s too purple add more baking soda. If it’s getting close to green then you added too much baking soda. You can add a little acid to push it back towards blue.
Step 8: Store in the refrigerator for up to 2 weeks. It might be fine for even longer, I just haven’t had time to test it yet.
And here’s a video tutorial because seeing it the process always makes it things simpler!
You can use this natural blue food coloring to make the most beautiful blue smoothies, smoothie bowls, ice cream, coconut whipped cream, frostings, raw “cheese”cakes, coconut sprinkles, and more! Or this little chocolate + blue jar which I will leave the recipe for below.
I will mention, in banana-based things it comes out much more purple than blue due to the slight yellow color of bananas. It is better in things that are actually white, with a base of coconut, cashew, or non-dairy milk.
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Chocolate Coconut Blue Swirl Jar
- Yield: 1 serving 1x
- 3 frozen bananas
- 3 tbsp cacao powder (or cocoa powder)
- 1/2 cup coconut cream
- 1 tsp blue food coloring from above
- 1/4 cup unsweetened shredded coconut
- 1/2 tsp blue food coloring from above
- Sprinkles: Combine the ingredients in a small bowl. Mix to coat the coconut thoroughly. Lay out on a plate. Put in a dry place overnight or until dry to the touch.
- Chocolate Layer: Blend in a high speed blender until smooth. Fill the jar halfway. Se aside the remaining nicecream in the freezer.
- Blue Coconut Layer: Stir the blue food coloring into the coconut cream. Adjust to your desired shade of blue. Layer on top of the chocolate and swirl with a chopstick.
- Freeze for 30 minutes to solidify the coconut layer.
- Top with the remaining chocolate nicecream. Add the sprinkles. Enjoy!
Leah M @ love me, feed me says
This is so fun!! I want to make this and dye everything blueeee! I have seen the purple cabbage + baking soda trick to make blue dye before and wanted to try tie dying clothes with it, but never even thought to use it for food! Can’t get over the vibrancy!!
Huh, I never thought of it for clothes. I always just used those dyes that came in a bottle for tie dying things, but that would be fun to do with all natural colors too! Smoothies, shirts–same difference 😀
I tried and tried to get blue but never got there (just a grayish purple). And that was after adding, incrementally, over 3x the maximum amount of baking soda. I reduced the cabbage water to just under 1/2 cup and added it to white frosting.
I ended up using the straight cabbage water to make purple frosting.
So odd that everyone else got blue!
Johanna Breuch says
I figured it out!! If someone has the same problem (didnt try it yet though)!
You probably also used those little packages of baking soda, which is indeed a combination of soda AND some kind of acid. I experimented a bit and put acid in the solution which made it a bright pink, i then tried to put some of my backing soda in a really small amount of the solution which, surprisingly, also turned it pink. This explains why you need waaay more of that soda. So now i will go and hopefully find pure baking soda.
Mine turned a gross gray/purple, as well. So disappointing! I only added pure Baking Soda, and the blue color never came. Now I’ve got a house that smells like cabbage and no blue coloring. 🙁
Johanna Breuch says
Same here 🙁
I love this! Who would have thought?! Can’t wait to try!
I must admit I kinda doubted it would work at first. Don’t know why, it is science after all. It was really fun to play around with, I’ve been adding it to all sorts of things now 🙂
🙂 How many halfs of red cabbage did you go through before it worked. Great idea, but as with so many other on here commenting, it didn’t really work out on my side. I put it into an airtight jar and kept it for a week in the fridge and when I opened it, it through me almost back to the wall. Yuck. Never smelled anything that bad. Any Ideas?
Aimee | Wallflower Kitchen says
I’m pretty excited about this. Something THAT colour that’s completely natural! Amazing, Natalie!! I am imagining lot’s of desserts using this food colouring recipe in my horizon… <3
I was already imagining one of your amazing ice creams in this color actually while writing this post haha 😀 I just love your ice creams and the way you photograph them so much!
Demeter | Beaming Baker says
The second I saw that shade of blue, I was like, “this is gonna be fun!” And you did not disappoint, Natalie! 🙂 This blue is so pretty and peaceful, like the color of fairies or something. 🙂 So funny, because I’ve heard many food bloggers get comments that recipes unintentionally turning blue, and I wondered what that was all about. Fortunately, yours is a beautiful intentional blue–which makes it SO much better. Alright, I cannot wait to see your “crazy cake idea”!! Are there clouds in it? Tell me there are clouds! Lol. And, coconut as sprinkles? GENIUS. I’d expect nothing less from you. Did that sound like I said it in a stern voice? With my eyes glaring at you over my glasses? Lol. Thank you for always keepin’ it creative, Nat. Have an awesome weekend. Muah! xo
All I could think with this shade was the color of boy baby showers, so thank goodness you planned a different though in my head! Fairies are much cooler 🙂 I know, I’ve seen a few accidentally blue smoothie jars floating around too and I was always like HOWWWWW!?!!? Tell me your ways, don’t just tell me it was a happy accident that I can’t replicate! Or all those people using blue spirulina…no, just no. I just can’t do that mouthful of algae taste ? CLOUDS! How could I forget the clouds! Better go redo the cake then, lol. No clouds per say…but you are surprisingly close actually 😉 Hahaha the first time I read it I didn’t hear the stern voice, but actually I can totally imagine it coming from a woman who looks shockingly like Professor McGonagall while glaring at me over the top of her spectacles. I do hope you are an HP fan so that makes some actual sense haha! I can already foresee popsicles in my weekend, so it will of course be awesome! <3
Amazing! Ok, few questions: does it give a cabbage flavor? And can it be frozen for future use? How about thickening it with some starch? Thanks for sharing this! It’s a beautiful color and a great idea! I’ll go cook my red cabbage now!
Hi Daniela! Nope, you cannot taste the cabbage at all. The only thing to be cautious of is adding too much baking soda which will make it taste salty, that’s why I would try not to use more than 1/2 tsp. As long as you are putting it into something sweet or with a flavor of it’s own it will be fine. Hmmm I haven’t tried freezing it, but as it’s mostly just water I don’t see why not! Good luck 🙂
thanks for your reply, I made it, I froze part of it, we’ll see if it was affected once I defrost it, and I thickened the rest so it’s not so watery. I’ll see what happens when I use it. Thanks again for sharing this!
Keep me updated Daniela!
The Vegan 8 says
Wow, you are on a posting roll, I”m trying to keep up with all of them, LOL! This is such an amazing idea, that is sooo cool that you heard about that trick….this is the first time I’ve heard about it, it is so cool! I know that baking soda and sunflower seeds cause things to turn green when baking so I can see how baking soda and cabbage could turn a cool color. This blue is just spectacular and beautiful! Blue and brown are a classic design color combo too! Just love, love this Natalie!!
Tell me about it! I think I’m taking this whole next week off, I have been posting way too much and neglecting pretty much everything else lately lol. Ha I’ve never heard of the sunflower seed thing, that sounds like a fun experiment too! Who knew baking soda had such magical powers!?! I like the blue with brown color thing too. Blue and turquoise would’ve been ever cooler, but I’ll take what I can get 🙂
audrey @ unconventional baker says
So pretty! I loved playing around with cabbage and baking soda — that’s how I got those pretty blues as well that one time 🙂 Only trouble is to take care not to mix it with too much maple, etc. since it starts to turn green… 😮
Ha good to know! I guess maple syrup is alkaline in some way?? Idk. I remember your blue cake adventures, thank goodness for whole blueberries 🙂 Have you tried butterfly pea flower yet?
audrey @ unconventional baker says
No, it’s yellow. And yellow + blue = green! I ordered butterfly pea flower over a month ago and it’s stuck in a post office in Thailand somewhere.. so one day I’ll get to play around with it, but who knows when at this rate… :s
Tiina @myberryforest says
Hi there (again!!) Just popped by to watch this video with my kids (they are big fans!!). I bought red cabbage!!!!!! I simply have to try this. I need this BLUE for my Unicorn party 🙂 🙂 🙂 🙂 You’re more than welcome to join. going to tag you in the results (if it all works out). <3
Yay yay yay!!! Oooh I am so excited to see what blue things you come up with! You know I’ll be there, it sounds much too fun to miss 🙂
Tiina @myberryforest says
It’s simmering now as I write this..so excited!! Hahah I feel like a little kid – a feeling which I really really love, and I’m guessing you do too 😉
Becky Striepe says
This is genius!! Blue is such a tough color to make, and you nailed it.
Blue has been one of my food goals for a while now, I was pretty excited about finding this trick! Thanks Becky 🙂
This is kind of incredible. Now I just wish I had red cabbage . . .
It was actually surprisingly hard to find a whole head of that to do this recipe, I had to go to 2 stores and got the very last head. But let me know if you try it, it is pretty fun 🙂
Hi. Thank you for taking the time to post this recipe. When used as frosting, did you add any sugar to sweeten it up?
Hi Michele! Yes I would definitely recommend adding some sort of sweetener if you are using it in a frosting, otherwise it may have a slightly bitter taste. My favorite easy frosting is a mix coconut butter, maple syrup, and non-dairy milk which you could easily turn blue with this food coloring. Hope that helps!
Would the colour of the maple syrup affect the blue colour?
It depends on in what and how you are using it. A small amount of maple syrup added to the coconut cream or frosting will be fine, but in large amounts and without a pure white base yes it will dull the blue color.
Behzad maha says
I really like blue.
I was wondering if I can use this to make my homemade candy blue?
Because I add color in the pot at the last minute and the high heat might burn it.
I have not tested it in high heat, so I’m not sure how that will affect the color but it’s worth a try. I don’t think it will burn, but it may change/dull the color.
behzad maha says
thank you for quick reply,
someone told me that Mallow also can give a mild blue color.
I will definitely try them and keep you updated.
Hi Natalie, this is SO awesome! 😀 Do you think adding some of this to a vegan shamrock shake could give it a cooler hue? I’m thinking along the lines of Baskin Robbins’ mint chocolate chip. I have no problem with the more yellow-green look, but can’t help but be curious……
Hmmm I can’t say for sure, it depends on what else is in the shake. Banana-based smoothies/ice creams don’t take the color as well, it works best on coconut or yogurt based things. I find spirulina works really well for that cool blue-ish green color though!
Hello! What a great recipe. I’m wondering if there have been any updates on the “shelf-life” of this? Is it perishable? I’d like to use it for non-food items and want to understand if it’ll give them an expiration date.
It is definitely perishable, I would say 4-6 weeks max before it starts smelling funky and is probably not safe for use/consumption. Hope that helps!
Thanks so much. We’ve just got the coloured water alone in jars without any baking soda. I’ll keep y’all posted! Blue is my favourite flavour of food, so this recipe is extra great 🙂
Sandy Leibowitz says
I was keeping my eye on this for a while and then decided to give this a chance when making my daughter’s birthday cake. I followed the directions and it really did not work well 🙁
It wasn’t turning blue unless I added too much basking soda, and as you said – it was metallic and salty. Even then, it was a dark, almost navy blue – not light blue as your beautiful photos. The only thing that I think might have gone wrong was I may have not reduced the red cabbage liquid exactly to what you mentioned. Any other pointers? Thanks!
Hmm not reducing it could definitely affect/dull the color, it does take quite a while to reduce enough to give you a really concentrated blue. I’m sure it can vary from cabbage to cabbage since we are working with a natural ingredient here too. I’m sorry it didn’t work out though, have you perhaps considered trying the butterfly pea flower instead? I know it’s a pain to have to order such a specialty ingredient, but it is really easy to use once you have it and one bag goes a long ways 🙂
I haven’t but I will. Thank you!
Jenny from jennyisbaking.com says
Hi Natalie, I hate artifical food coloring. So happy I stumbled across your blog! This looks so awesome!
Would it work with regular milk and/or butter? I’m not a vegan, but was considering this for a buttercream cake. Happy to hear back from you.
Hmm I have not tried it in frosting with real butter so I can’t say for sure. From my experience with making frosting I know it takes a lot to create a really bright color so I worry it might just be too much liquid since it’s much thinner than a typical food coloring consistency. It might work, I just don’t want you to waste all that time and an entire batch of frosting. Have you heard of/thought about trying this: https://bluechai.com/shop/blue-matcha/
Hey, this looks great!! Do you think it will work with a batter of vegan vanilla sponge cake?
I’m trying to have the cake itself blue and was wondering if it will maintain the color after baking. The recipe I have for the batter contains vinegar, so I’m not sure it will stay blue.
I do not think it will stay blue during baking either unfortunately, or at least not a very attractive shade of blue. Sorry!
This did not work for me. I was attempting a blue buttercream for my son’s 2nd birthday cake. Sky, clouds, airplane. It never turned blue, just grey. The cabbage water smelled horrible too. I persisted hoping to trust what others had said about it not affecting the taste. In the end I had a grey cake with white clouds. Oh well. It still tasted great and my guests laughed with me about my disasterous grey icing.
Ache Mist says
Baking Soda AKA Sodium Bicarbonate AKA E500
Not all E numbers or things with chemical names are artificial.
That being said, this is a great way to get blue food colouring with a little effort.
It was fun making it and testing on white products like milk, mascarpone and ricotta cheese. As you said in one of replies to the comments baking eliminated the blue color altogether but the icing came out cool. One downside was the smell because it wasn’t overpowering but distinctly cabbaggie. I’m wondering if you had any issue like that with icing and any suggestion of how to overcome this? Thank you
Angela Calabrese says
I am wondering how I can use this to make a smoothie blue. I feel like adding it to anything with berries will just make it purple. It’s a great idea and I am wondering if I am missing something?
This really works best in things that are pure white like coconut cream, any other fruits/colors will throw it off. The easiest way to make a blue smoothie is with blue spirulina, this is the kind I use it has basically no flavor: https://www.unicornsuperfoods.com/collections/superfood-collection/products/100-natural-blue-spirulina-powder
This looks fabulous.
Can I ask if this BAKES blue?
Does heat affect the shade in cake?
I haven’t tried it personally, but I think baking will destroy the color unfortunately. Have you heard of blue spirulina? That’s a really easy way to get naturally blue foods that may hold up better to heat. This is the one I use: https://www.unicornsuperfoods.com/collections/superfood-collection/products/100-natural-blue-spirulina-powder
Hi, Has anyone tried using the coloring for a punch recipe? Are there any basic punch ingredients that it would not mix well with? My hope is to use for boy baby shower punch.
Hmm haven’t tried it, and anything acidic will mess up the blue color (turn it purple) so probably won’t work for punch. Blue spirulina would work better (and really doesn’t have much flavor) for blue, that’s the only other natural blue colorant I know of💙 If you google it it’s pretty easy to find online!
Thank you very much for your reply.
Didn’t work! I reduced it to the amount mentioned. Added baking soda only up to the 1/2 tsp recommended and it was still purple. Added it to the icing anyway and barely turned purple, watered down the icicng, and made it grainy.
Haven’t tried this, but as I read comments from people saying it didn’t work I couldn’t help but wonder if cabbages that were sprayed with something would not work as well. Does it make a difference if the cabbage is organic or not? Maybe washing the cabbage really well first might help? I don’t know, just guessing as to why it doesn’t work for some. I do want to try it for myself.