Instructables

Color-Changing Cocktails

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Blue foods are striking (and rare) all by themselves, but add a little lime juice and this emerald blue elixir will *magically* change into a brilliant purple. I've named my little cocktail the Indigo Blush. The intense color is completely natural (from a flower!) it's not difficult to make, and the color transformation is truly stunning. The basil/lime/gin flavor combination is bright, refreshing, and dangerously drinkable.  If you're impatient and just want the recipe, go ahead and skip to the last step. Read on for my full, exhaustive treatise on color-changing foods.

Some recipes start from an idea and just magically come together when the ingredients are in my hands. Others take years of fiddling, research, scrapping the whole idea and starting again, more fiddling, seeking expert advise,  testing and retesting before satisfying results emerge. This recipe is definitely in the latter group. The idea of a color-changing recipe is one of those white whales I have been chasing for years, and finally, I have a dish I'm excited to share. 

When I first read about color changing food pigments I could barely contain my glee. I mean, think of the possibilities: a dish that can change COLORS? It turns out that lots of plants have pigment molecules that are pH indicators. In a neutral or basic solution they will appear green-blue or blue-purple, but add some acid and they'll turn purple or red. (You've probably seen examples of this already: blueberries in blueberry pancakes will sometimes turn green if the batter has too much baking soda, or brush your teeth with a baking soda toothpaste after drinking a glass of red wine and you'll end up with a mouthful of blue foam.)  Lots of dishes get a little something acidic thrown in at the end, so it didn't seem like making a dish to use this color-change trick would be too difficult.

My very first experiments quickly showed that I would need a mostly clear solution in order to show off the color change. (Opaque foods just muddied it up and got in the way). So I got to work trying out all sorts of ingredients with color-changing pigments: radicchio, red cabbage, blueberries. The findings of these tests were disappointing. Either the color would come out muddied and dull (blueberries) or the flavor would be horrid (red cabbage) or both (radicchio). And that's not even getting to the hardest part: acidity. Nearly everything that we eat is acidic. Egg whites and most tap water are slightly basic, but everything else is just varying degrees of acidity. For the color change to work, you need an acid addition that will significantly change the pH, but not until the dish is served. (So adding any acid to the mix beforehand is a no-go.) And this makes adding any flavor difficult. Just about every flavor-enhancing technique I thought of either muddied up the color or added acid. Perhaps, I thought, this is a phenomenon that works great in an eighth grade chemistry class, but really shouldn't be brought into the kitchen.

And then I met this little blue flower. (Hello, butterfly blue pea flower!) It doesn't seem to have much of an audience in the US yet, but Thai and Chinese cooks have long used this little flower to color foods and make teas with a brilliant blue hue. For my money, this is truly a remarkable ingredient. For one thing, it's hard to overstate how brilliant the color from this flower is. The pigment is highly soluble-- you don't even have to boil it to release the color. And since the flowers can be dried, it is easy to keep them on hand. The only slight detractor is that they don't have any real flavor on their own. But even that negative can be a boon-- you could use these little guys to color any sort of dish, and add whatever flavors you want separately. Finally I had an ideal candidate to make a color-changing recipe, and I decided a fancy cocktail would be just the thing to showcase this remarkable little ingredient. I chose to make an alcoholic beverage, but there is no reason that the same techniques wouldn't work for non-alcoholic beverages. 
 
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Brilliant but slightly mad idea. I'm not keen on basil but I like gin, vodka and lime juice, so I might "experiment" a bit for other flavours...
poofrabbit10 months ago
Congratulations on your 2nd prize win in the play with you food contest!
This was a really cool idea- now, TO AMAZON!! :) thanks!!
rbahr10 months ago
Out of curiosity, If you put a lemon wedge on the side and allowed a customer to put it in their drink, would it slowly change colors if they dropped it in, or at the very least just squeezed it in?

Might be more satisfying for the customer to change the color.
kitchentablescraps (author)  rbahr10 months ago
Squeezing in lemon or lime juice would definitely work. I'm not quite sure about how placing an unsqueezed slice of lemon or orange in the drink would look... my guess is that it would slowly change color over time. I went with the liquid poured in, just because I felt it made the most dramatic presentation.
What you could try in order to do it with just the lime wedge is take a small sewing needle or pin and pierce each of the lime cells, that way the lime juice will get out much more quickly. A little labor intensive, but could work.
megnwayn10 months ago
Makendo did similar to this back in 2009. It would have been nice if you had acknowledged his instructable
kitchentablescraps (author)  megnwayn10 months ago
I actually hadn't read Makendo's very clever instructable until after publishing mine. Thanks for pointing me in that direction. I love the idea of using dry ice (I definitely never would have thought of that.) There are so many possibilities to create a color-changing dish-- for me, it's really exciting to see how other folks tackle a similar task in completely different ways.
Sheelanagig4210 months ago
I can't wait to try this as a bridesmaid gift. My only reservation is that Basil-Lemongrass might be too ... New a flavor profile. Any ideas for more approachable flavors?
Also, I'd like to be able to give them as a kit, should I just include fresh limes, since prepackaged juice would have the wrong pH?
kitchentablescraps (author)  Sheelanagig4210 months ago
Hmm, it's hard to say how flavor combinations will work until you give them a go, and what is an "approachable" taste is a hard thing to pin down. Making a syrup with most spices and herbs should work in a similar way. You could also try flavored syrups that are made for coffee. All I can say is that the basil was the clear favorite among the friends that I consulted with. But I'd be curious to hear how your tests go! Good luck! (Oh, and bottled lime juice would be fine to change the pH, I just prefer the flavor of fresh lime juice.)
awildeheart10 months ago
Hello, I live in north Queensland, Australia, and offer a word of caution about growing this plant. It has gone wild here in the tropics and poses a huge problem as it strangles and overtakes native vegetation. It climbs up trees, creating an impenetrable interlinked web over vast numbers of trees by creating both ground to canopy 'vines' and tree to tree 'vines' . Removing it entirely is very difficult as EACH leaf point is able to put down strong roots and carpet entire areas with one plant - that has now become an interconnected mass with strong roots anchoring it to the ground every few inches along. Birds also love this plant and readily spread the seeds. So, please consider the native environment carefully before planting this and ensure it doesn't escape from your garden. This photo is from part of my yard last year before I tried to get rid of it.
kitchentablescraps (author)  awildeheart10 months ago
Thanks for the caution-- it definitely sounds well founded! Here in the decidedly not-tropical northeastern US it takes some work just to get this plant to grow, so renegade invasion seems unlikely in this climate. A few other tips for folks who might want to grow this guy, but not propagate an invasive species: I grew my vine in a pot (potted plants are generally much easier to contain), if you harvest the whole flowers of this plant it won't produce the seed pods. So that would also reduce the chance of the seeds accidentally being spread to surrounding areas. Thanks, and good luck with your garden!
xenobiologista10 months ago
On names: the Malay name for this flower is bunga telang. The Latin generic name is "Clitoria" ;)

@awildeheart: Thanks for the warning. People who want to grow exotic species should be responsible for controlling them. Searching around, sounds like it's considered invasive in Australia and several Pacific island nations.
awildeheart10 months ago
Oops, the image didn't load with my post.
DSCF9080.JPG
n4nln10 months ago
The next step will be "clock reactions" that delay for a predictable amount of time before releasing the pH change. Doing this with edible and palatable reagents could be tricky, though.
GeeDeeKay10 months ago
Love this idea, and I've done it before with flashy, science-y success. It's essentially an edible Litmus strip... There is another instructable that uses red cabbage for the base purple color and dry ice to initiate the color change. The dry ice is a great effect as it cools the drink, creates an amazing white mist that spills over the rim of the glass, and is generally fun to play with anytime. 

Your method of using the flowers for the base solution is definitely cool, and the basil syrup is a fantastic idea, too! Dry ice should work with your base solution, as well, as it's also acidic. Nice work!
Tootallreefs10 months ago
very kool, i will be trying some variations on your mix will let you know how it turns out
kitchentablescraps (author)  Tootallreefs10 months ago
Excellent! Please do! Also: these kind souls with a pH tester compiled the pH levels of some common cocktail ingredients, which might be helpful for further experiments. http://stirrednotshakenblog.wordpress.com/2011/12/28/the-electric-cocktail-acid-test/
mtrodman10 months ago
this should be called a Bangkok Blush. The Thai pea flowers are perfect and definitive.
kitchentablescraps (author)  mtrodman10 months ago
Oooh. I like that-- it's got a great ring to it. I might have to use it...
MonkiMan10 months ago
interesting, so make a drink chuck full of anthocyanin's and then play around with the PH and watch the colour show!
kitchentablescraps (author)  MonkiMan10 months ago
Exactly!
rubbeldiekatz10 months ago
Why do chose to use plants and why especially this ones? I think you could have used any anthocyanin containing plant extract, for example red grape juice. But of course, grape juice is acidific, but you I am sure it can be diluted and have ph adjusted with something else.
kitchentablescraps (author)  rubbeldiekatz10 months ago
You're absolutely right, the anthocyanins in grapes (and blueberries and lots of other fruit) are also pH indicators. The difficulty with using these fruits is that the fruits themselves are quite acidic, so once you've juiced them, they're already well out of the color sensitive range. And adding a base? It's a bit easier said than done. Very few foods are basic enough to change an acidic juice to a neutral one.( In fact, baking soda is the only one I know of.) Try adding baking soda to juice, and it becomes unpalatable very quickly. So it's pretty easy to demonstrate color change in these fruits, but the hard part is making it something you actually want to eat. It's almost certainly possible, but so far it's proved beyond my culinary ingenuity.
forgot to post this link: http://en.wikipedia.org/wiki/Anthocyanin
Kiteman10 months ago
You can get out of your tree on Science!