In today’s dynamic and competitive industry, there’s a frequent need to stand out: to make a beer that is not only fresh, delicious, and high quality, but also just looks really cool. As brewers, the use of natural ingredients is often a point of pride; TTB regulations limit the additives that can be used to flavor and color beer without special recipe approval and using artificially derived coloring and flavoring often goes against the broad ethos of the brewing industry.
Anyone who has brewed with blueberries or blackberries will tell you the deep rich color of the berry is difficult to carry through to a final product. More often, beer turns out a shade of pink rather than the color of the whole berry. Without an enormous fruit addition that overwhelms the character of the beer, color is difficult to impart without an associated flavor.
Enter butterfly pea flower, the definitive and natural flavor-free way to turn your beer blue.
What Is It?
Butterfly pea flower is used as a tea in South East Asia. It is the flower of the Clitoria ternatea plant, more commonly known as Asian Pigeonwings or the Butterfly Pea. Dried flowers from the plant have historically been used as a medicinal tea in some Asian cultures but is most commonly seen as a brightly colored after-dinner beverage in Thailand and Malaysia where the flowers are steeped in hot water and flavored with honey and lemon. Butterfly pea flower is also used to color some Thai rice-based desserts. It’s been used as a dye for clothing for centuries, and more recently it has been used to color craft cocktails and – of course – beer.
The most dynamic and unique aspect to butterfly pea flower is not just that it turns beverages a deep, vibrant shade of blue, but that the color can change depending on the pH of the solution, acting like a pH test strip, and acting almost instantaneously. The internet is full of videos showing butterfly pea flower cocktails changing color as a lemon is squeezed into the drink.
How Do You Use It?
Like most ingredients, brewers everywhere will experiment in a multitude of ways to find the best possible application for their brewery, but Brian Quinn of Town Brewing Company in Charlotte, NC made a concentrated tea by steeping the flowers and then dosed in brite tank. “I ended up using about .45 pounds per barrel” says Quinn describing Indigo Wolf, his Session IPA an easy-drinking beer made with butterfly peaflower and Styrian Wolf hops. “I love the color we achieved with the beer. In skinnier glassware, it looks more blue than purple, but in a typical shaker pint sized glass, it is deep purple with a blue tinted head. Beautiful!”
Chais McCurry, Head Brewer at Fullsteam Brewery in Durham, NC found a similar dose rate successful when making The Warmest Color, a Juicy IPA. “We used about 7 pounds per 12bbl, just above .5 pounds per barrel. However, we used powder instead of whole leaf which is a different process. The trick is to do anything you can to get it to dissolve before pushing it into the tank. We used 185 degree water to make a Tea and added the powder and water at the same time. Then, we bubbled CO2 overnight for agitation and pretty much all of it dissolved.”
Butterfly pea flower tea is described as earthy and woody, akin to a green tea. McCurry describes it as “floral/fungal” with a more floral aroma. Quinn noted it has a, “Slight vegetal, cut grass aroma in the tea, that did not really translate to the final beer.” When presented with the beer, however, drinkers seem to take visual cues into account. “The beer is definitely something of mind trip,” says Quinn. “With the intense purple color, people seem to subconsciously expect a fruity beer, and always seem surprised to find a hop-forward session IPA. I have even had people tell me that it tastes like Grape Kool-Aid, but I am convinced that is just their mind playing tricks on them.”
In low pH (acidic) environments butterfly pea flower creates a pink hue, tending to deep fuchsia reminiscent of hibiscus. In high pH (basic) environments the color tends toward a flat green. But around 4.4 – 5.4 pH, the pH range of most non-acidic beers, the color is a vibrant blue, with hints of red that read a rich purple to the eye.
The chemical responsible for the color in butterfly pea flower is anthocyanin, a water-soluble pigment found in the skins of many fruits – including those berries that turn your beer pink. Even the reds and purples of autumn colors in trees are due to anthocyanin created in the sap of the leaves. The fact is, anthocyanin is an easy chemical to solubilize into beer – the difficult part is finding a high concentration source that will lend a vibrant color that won’t impart the flavor of its original source. Red cabbage is a source of 36 different types of anthocyanins, but it might be difficult to use enough red cabbage to positively affect the color of beer without imparting an unfortunately cabbage-y overtone.
The primary anthocyanin present in butterfly pea flower (as well as Cabernet Sauvignon grapes, cranberries, and pomegranates) is a delphinidin, and it is present in incredibly high concentration in butterfly pea flower petals. It tends to be more stable in the presence of heat and a higher pH (more neutral) solutions than many other anthocyanin compounds and while all anthocyanins change color depending on pH, the reaction is less pronounced or inert in less stable compounds or in lower solubilized concentrations, making the butterfly pea flower a perfect natural color additive for beverages.
However, butterfly pea flower also contains a high concentration of ferulic acid, the precursor to 4-vinyl- guaiacol (4VG), which lends beer a distinct clove-like aroma. Some ale yeasts, like those used to produce weizens, some Belgian yeast strains, or wild yeasts – particularly Saccharomyces diastaticus – can express 4VG. Any fermentation in the presence of butterfly pea flower without careful choice of yeast strain may exhibit this clove character, and it might not be your desired outcome. It’s another great reason to add butterfly pea flower coloring post-fermentation and even post-filtration.
McCurry also cautions to double wash – or at least closely monitor – any kegs that have held a butterfly pea flower beer. “It is definitely a food color that will wash out”, he says, “But it may need some extra cycles on the keg washer.”
Stylistic Choices
Imagine an American Wheat Ale colored to a vibrant blue using butterfly pea flower, accompanied by a wedge of lemon on the side of the glass that changes the color of the beer to a bright pink when squeezed in, or Quinn’s idea: a regular, tart Berliner Weisse served with an accompanying shot of butterfly pea flower syrup that turns pink when poured into the beer. The combinations are endless and the experimentation has just begun in the world of blue hued brews.
Both Quinn and McCurry opted for IPAs with their butterfly pea flower beers, though many other breweries opted for sour beers, tending toward the pink and fuchsia end of the color spectrum, sometimes with other fruit or spice additions for additional color or flavor characteristics that matched the color of the beer.
Regardless of the style, Quinn reinforces the idea that making beer in a commercial setting is not always just about the flavor. “While the flavor contribution from the butterfly pea flowers is minimal, aesthetics are very important in brewing,” he says, “People see a beer before they ever taste or smell it. Butterfly pea beers may be a little gimmicky and subject to the same criticism glitter beers have received, but at the end of the day, beer is supposed to be fun. “
