There are two kinds of milk punch. The first, typically called brandy milk punch or bourbon milk punch, is popular in New Orleans, is citrus-free, and includes milk. The second type, often called English milk punch or clarified milk punch, is what we’ll focus on here. From this point on, we’ll refer to it simply as milk punch.

The base recipe for milk punch includes citrus juice or another acidic ingredient. Milk (usually hot milk) is added to the mixed cocktail, curdling the milk, and then the punch is strained to remove the curds. The process removes most of the color and cloudiness from the drink, clarifying it, and it preserves the cocktail from spoilage for months or even years if kept cool. After Charles Dickens died in 1870, bottles of milk punch were found in his wine cellar.

The concept of clarifying cocktails with milk might seem a bit odd today, but in the milk punch heyday—the 1700s through the mid-1800s—spirits would have been far rougher around the edges than those we enjoy today, and in addition to clarifying and preserving the drink, the process also softened the harsh flavor of the booze. The resulting drink is unctuous and silky, clear and only subtly milky, with softer, mellow flavors.

And today? You may not need to soften the flavored edges of your spirits, but the drink offers advantages to bartenders in top cocktail lounges: It can be batched in advance for speed and consistency rather than assembled to order, it does not spoil if handled appropriately, and it makes serving easy. Most bartenders simply pour refrigerated milk punch into a stemmed cocktail glass or over a large ice cube. At most, it’s mixed with soda water and garnished with a citrus peel.

This means that milk punch also a great option for the home bartender. It can be mixed and clarified ahead of time, then stored in the fridge, ready for your next holiday party (or after-work tipple). The milk punch process can be applied not only to traditional punch recipes, but to other classic drinks, giving a White Russian, Midori sour, or Ramos gin fizz an inventive edge.

BACK TO BASICS

The earliest known milk punch recipe, as reported by cocktail historian David Wondrich in his book Punch, dates to 1711, and is attributed to housewife Mary Rockett. That recipe calls for a gallon of brandy, five quarts of water, eight lemons, and two pounds of sugar. To it, two gallons of scalding hot “new milk” are added, and after an hour, it is strained through a flannel bag.

Benjamin Franklin wrote a recipe for milk punch in a letter dated 1763. It’s a bit boozier and less sweet than the earlier recipe, but sticks to the same basic formula, with added nutmeg.

By the time the first bartenders’ guide was published in 1862, Jerry Thomas’s recipe for English milk punch contained brandy plus rum and arrack, lemons and pineapples, green tea, cloves, coriander, and cinnamon. Many of today’s bartenders use this recipe as their starting point before playing with everything from camel to coconut milk and rejiggering the process.

WHAT IS GOING ON HERE?

To understand what’s happening when making this clarified concoction, we can look to consommé, wine making, and sauce making for help.

To make consommé, egg white proteins coagulate in a cloudy stock as it’s heated, forming a 3-D network of sorts, trapping the liquid’s cloudiness-producing particles and forming the solid “raft,” which eventually floats to the top. The raft is skimmed off and the remainder is a clear liquid.

For milk punch, bartenders accomplish much the same thing but use milk proteins instead of egg white proteins; use acids to curdle the milk and coagulate its casein proteins rather than heat alone; and the raft of curds (often called a nest) sinks to the bottom of the container instead of floating to the top. In the cocktail world the technique is generally called milk washing and can be used on spirits alone or on a full cocktail. Egg washing is the same process but with raw egg whites instead.

In addition to clarifying, milk washing also softens the harshness of the flavor of the punch ingredients, stripping out astringent-tasting tannins and other polyphenols. Tannins are most noticeable in foods and drinks like wood-aged spirits, red wine, black tea, the skins of nuts, and immature fruit. (Tannins and woodiness are desired flavors in many of these other drinks, but too much of a good thing is problematic – think over-steeped tea. Removing them in milk punch can fix some excessive-tannin flaws, if present, but also helps marry flavors together into a soft and luscious whole.)

When consumed alone, the tannins in these foods and beverages bond with proteins in our saliva, giving us that astringent sensation in our mouths. But if we add milk to the tannic liquid, the tannins will bind with the milk proteins instead of those in our saliva. In sauces with red wine reductions, for example, tannins concentrate as the wine is boiled down. This means that they have the potential to taste overwhelming, except for the fact that proteins from the sauce’s meat bind with wine tannins to help neutralize the astringent sensation.

Milk, along with other animal proteins like egg whites and even blood, have long been used in the wine fining process to reduce tannins and help settle out solids from the fermented juice. But this process generally uses small amounts of fining agents, like Bentonite clay and Chitosan, in a large volume of wine and can take a long time to settle. Milk or egg-washing, on the other hand, is done relatively quickly to preserve fresh or spoilable ingredients.

PROCEDURAL MATTERS: CURDLE IT

Traditional recipes for milk punch call for the cocktail ingredients to be combined and added to near-boiling milk, before allowing the cocktail to rest, and then straining it. But a look at current bartender practices opened up a whole new realm of choice for the cocktail maker—from milk temperature, to the order of alcohol addition, to resting time, to choice of filter. And that’s not even including what ingredients you decide to put in the damn thing.

First up? The temperature of the milk. Some bartenders have abandoned its near-boiling status. Nico De Soto, the beverage director at Mace in New York and Danico in Paris, and Chad Arnholt, one half of the consulting firm Tin Roof Drink Community along with Claire Sprouse, say it’s not really necessary to heat the milk, while others claim it is crucial. But nearly everyone agrees that you add the cocktail to the milk, rather than adding the milk to the cocktail, so that it does not instantly curdle.

Some bartenders also wait to add the alcohol until after the milk is curdled. Eamon Rockey of New York’s Betony curdles the warm milk with only the citrus first, then adds the remaining nonalcoholic cocktail ingredients and filters (the booze comes later). Luuk Gerritsen of the forthcoming Luke’s Cocktailbar on Curaçao says, “I feel that clarifying without alcohol gives cleaner results, though with brown spirits you don’t really have a choice [if you want your punch to be clear].” In contrast, De Soto says he finds the final drink to be more “harsh” if you wait to add the liquor until after clarification. Milk washing also strips out woody flavors from aged spirits, so much of this before-or-after decision is based on whether you want those flavors integrated into the cocktail or kept out.

PROCEDURAL MATTERS: REST IT

As the milk breaks, most bartenders continue to stir gently, and then wait for anywhere from ten minutes to an hour to let the mixture fully curdle and settle. (And some wait a few days.) Bartenders have also taken to letting the ingredients rest at different stages, to better integrate flavors and to make a richer cocktail. After adding milk to curdle the mix, bartenders, including Restaurant 1833’s Josh Perry in Monterey, California, and Donnie Pratt of Cucina 24 in Asheville, North Carolina, let theirs rest overnight before straining.

Gareth Howells of VYNL in Manhattan rests his punches at three different points: during the initial mixing of the cocktail (“I find it offers the finished product the best depth of flavor,” he says), after curdling but before filtering (“I find it really mellows out and softens the finished product”), and after the product is filtered but before serving (“this resting period really helps harmonize the flavors of the punch as ‘just filtered’ punch can tend to drink very bright and sometimes a little raw”).

PROCEDURAL MATTERS: FILTER IT

The ingredients are mixed, the milk is curdled, and you’ve let the cocktail rest (at least a little while). Now it’s time for the tricky part: straining the mixture through a filter. The curds did the work of clarifying the cocktail, and now they need to go.

It’s important to remember that the curds filter the cocktail, not the cloth through which the liquids drip out. As you filter through a cloth, the remaining stray proteins and cloudy bits left in the liquid will get stuck in the nest of curds that has formed at the bottom of the container. Milk punch makers are careful not to disturb the nest too much, because should a channel open up in it for liquid to flow through the nest without passing through the glop, the cloudy suspended particles will be carried along the liquid.

As for the choice of filter? Many bartenders polled use a Superbag (an expensive net bag with fine holes), or cheesecloth lining a conical chinois or china cap. Arnholt has settled on a cooking oil filter (which looks like a big coffee filter) inside a china cap. Rockey says, “The most effective filtration support mediums are those that are a single layer, durable, tightly knit, organic material; a standard restaurant tablecloth is a great example of this type of filtration support medium.”

INGREDIENT MATTERS: MILK

While milk punch was traditionally made with whole milk, today the milk choices (everything from fat level to which animal or nut it’s derived from) are endless, and bartenders have been experimenting.

Gerritsen experimented with several types of milks for his punches. He found that nonfat and low-fat milks didn’t curdle well, that whole and half-and-half were best (and that unpasteurized milk was even better). He was able to use cream, but disliked the flavor, saying it gave an “off-putting fatty nose” to the final punch. Sour cream failed, but buttermilk lent a “non-citrus acidity” to the final product. Arnholt called the buttermilk clarification “cheesy” in a way that doesn’t sound pleasant, and also prefers fresh, lightly pasteurized milk to “macromilk.” Christopher Sinclair from the Red Rabbit Kitchen and Bar in Sacramento uses half-and-half, partly due to its high fat content, but also because that’s what they typically have behind the bar. Peña uses 2 parts whole milk to 1 part half-and-half.

The milk doesn’t have to come from a cow. Gabriella Mlynarczyk, beverage director at Birch restaurant in Los Angeles, experimented with full-fat cow milk, full-fat goat milk, full-fat sheep milk, and full-fat coconut milk. “Goat gave me by far the best flavor and most rapid clarification,” she says. At Loló in San Francisco, bartenders use a ratio of 1 part goat’s milk to 5 parts cocktail in their milk punch. And Paul Bradley of Gold on 27 in Dubai says he once made a date and camel-milk punch as an experiment.

Nut milks are another story. Rockey says, “While some vegetable milks (like soy milk) contain a great deal of protein and can be curdled, I have never had success with vegetable milks at producing clear milk punch.” Kaiko Tulloch of Lucky Liquor in Edinburgh says she tried almond milk but ended up needing to add whole milk for her “clarified horchata” with tequila. Perry mixes coconut milk with cow’s milk in his recipe for the same reason.

INGREDIENT MATTERS: ACID

But milk is only one half of the magic; acid to curdle it is the other. The bartenders we spoke to have used lemon, lime, grapefruit, orange, pineapple, and yuzu juices, white verjus, and kiwis (in oleo saccharum form) as the acid agent in their punches. Some have even gone so far as to use powdered citric acid, malic acid, or lactart.

Bartenders say that not much milk nor much acid are strictly necessary to make the milk curdle, but that increased amounts are a matter of final recipe taste and ease of filtering. Rockey notes, “Very little milk is actually required to clarify a punch; it is more important to consider how much surface area the broken curds will need to cover to create a sufficient nest for the punch to clarify.”

In other words, you want enough of a bottom layer of curds for the liquid to run through during filtration, or else you’ll get colored solids in the final result. Additionally, more milk should lend a more creamy and rich finished punch, and typically a good amount of acid is generally required for a balanced cocktail anyway.

BACK TO THE TEST KITCHEN

[Ed note: After Camper English delivered his milk punch story to the Cook’s Science team, Executive Editor Dan Souza began developing his own recipes for the home cook. The following is from his perspective.]

I could happily keep testing milk punch recipes forever. I don’t often say that about a recipe I’ve been toiling over for weeks, but milk punch is just different. Camper’s exhaustive survey of professional bartenders’ riffs on the milk punch form should give a pretty good hint at how many variables there are to play with. But beyond providing an excuse to geek out on casein proteins, pH, and filtration, milk punch is just fun and tasty. The transformation from cloudy, inky punch to the crystal-clear blush of a pink wine is very satisfying. And that’s all before you even get drunk on the stuff.

I started by using a very basic punch recipe, with brandy, lemon juice, and sugar. I figured I would iron out all the procedural details, so I could move on to flavor variations.

My first big question: Is it actually important that you add the punch to the milk and not the milk to the punch? I wrote in my notes that this rule smacked of old-timey milk punch lore that was probably ripe for debunking.

I was wrong.

Just a couple of tests proved that order of operations is very important. Adding milk to the punch invariably resulted in a twisted mass of curds suspended irregularly within the punch. This happens because the milk comes in contact with the highly acidic punch and coagulates on impact. The result is that only a portion of the punch actually gets clarified, giving you a colorful (in a bad way!), cloudy drink. Adding the punch to milk might not seem all that different at first glance, but it’s all about rate of acidification. As the (acidic) punch streams into the milk, it slowly (relative to the milk-into-punch method) drops the pH of the milk. Once all the punch is in the milk, the pH is low enough (lower than 4.6, the pH at which casein proteins precipitate, or fall out of solution) for it to curdle. At that point the milk and punch are evenly mixed, so when the milk curdles it’s able to trap impurities from the entire mass.

I was also incredibly curious about the hot milk–cold milk rift in milk punch practice, so that’s where I focused next. With three different base punches I tested 40-degree-F whole milk versus 180-degree-F whole milk (adding the punch to the milk in each case, of course). The biggest difference I noticed was the size of the curds that formed. When I used hot milk, the curdling reaction happened more quickly, and I ended up with larger curds. When I used cold milk, the curds were far smaller and more evenly distributed throughout. Just as with order of operations, the larger, faster-forming curds often didn’t clarify the drink quite as thoroughly as the smaller, slower-forming curds. I say “often” because there were plenty of times that hot milk worked just fine. But I consistently got the best results using cold milk. Added bonus? No need to heat up the milk.

So at this point I knew I would be adding punch to cold milk. Great! The next logical question is what type of milk is best? I limited my testing here to pasteurized, homogenized dairy from cows and focused primarily on fat content. I had a hunch that using a lower-fat milk, which is proportionally higher in protein (the stuff that does the clarifying) would make for a better clarification.

I was wrong. Again.

My tests with skim milk looked promising at first—the milk mass curdled nicely and fell to the bottom of the glass much faster than with whole milk—but the resulting milk punch was always cloudy. Half-and-half reacted completely differently. Thanks to its abundant fat content, the curds never actually sank to the bottom, but rather stayed suspended at the top. Half-and-half often produced a relatively clear punch but not every time. Call it the goldilocks effect, but middle-of-the-road whole milk emerged as the best clarifier in my tests.

Finally I took a look at filtration. As with every recipe I test, I wanted to start simple and only introduce special equipment or techniques as needed. Luckily for me (and, well, everyone who likes convenience and drinking), a coffee filter set in a fine-mesh strainer does the job admirably. The real key to getting superclear milk punch is pouring the curdled punch into the strainer slowly, and after it drains completely, filtering it through once again. The coffee filter does a lot of the heavy lifting, but the nest of curds sitting on the bottom of the filter sops up the really fine stuff.

At this point in the process, I was ready to play around with actual recipes. And so I started at the beginning—the very beginning. I made a batch of the earliest known milk punch recipe, which is credited to Mary Rockett in David Wondrich’s lovely book Punch. It’s a simple mixture of brandy, water, lemon juice, lemon peel, and sugar that, once clarified, looks like chardonnay and drinks like a refreshing limoncello cocktail. It calls for a 4:1 ratio of punch to milk for the clarification, which turned out to be a great ratio for all my recipes. My adaptations to Rockett’s original recipe are few: I use cold milk in place of hot, add orange peel and orange juice to the lemon for a more complex citrus flavor, and scale it down to make one quart. You can get my recipe here.

While I was reading Wondrich’s book, I was pulled in by a couple of other old punch recipes that he had uncovered—but ones that weren’t traditionally clarified with milk. One was Ruby Punch, a recipe Wondrich found in Jerry Thomas’s Bar-Tenders Guide from 1862 that features a seriously tasty combination of black tea, ruby port, lemon, and a funky rum-esque liquor called Batavia Arrack. The other was Billy Dawson’s Punch, which in classic English punch form, combines both brandy and rum with, oddly enough, some dark beer like porter or stout and richly flavored Demerara sugar. They are both delicious on their own, but I really loved how they changed with milk clarification.

The Ruby Punch, originally rich in tannins and color from both strong tea and port, turns silky smooth and fruity after clarification, and its color change is dramatic—from inky plum to a light rosé wine. Come to think of it, if you like rosé, I think you’ll love this one. Billy Dawson’s concoction is a more spirit-forward, less fruity affair that would feel right at home in a snifter sitting on a mahogany desk surrounded by leather-bound books (I think you know what I’m talking about). My milk-clarified version is full-bodied, amber-hued, and smooth. You still taste the brandy and the molasses-like demerara, but there are no rough edges to keep it from going down easy.

RECIPES

Mary Rockett’s Citrus Milk Punch

Billy Dawson’s Milk Punch

Black Tea-Port Milk Punch

Photography by Kevin White.

In his book Taste Matters, John Prescott suggests that there’s an evolutionary reason we crave that balance: A piece of fruit that’s ripe has that same perfect-tasting sweet-sour proportion, while an under- or overripe fruit tastes out of balance.

But sourness is not a simple phenomenon. When you squeeze a lemon into a drink, you’re adding citric acid, which carries a particular taste that’s not just sour but a distinctive type of sour. A lime gives a drink a different kind of sourness, since it contains not only citric acid, but also malic acid and a small but significant amount of succinic acid, each of which adds something different. Still another type of acidity comes if you mix a cocktail with champagne or vermouth, which contain tartaric acid from the wine grapes they’re made with.

Contemporary bartenders, in their tireless pursuit of delicious concoctions, have realized that fruits and wines aren’t the only ways to get those acids into a drink. Cooks don’t grab a salty ingredient to get salt into a dish; we short-cut to the pure form. Citric, malic, tartaric, and other acids are sold in their pure powder forms on the Internet and can be added to cocktails in milligram amounts to precisely dial in the strength and type of acidity a bartender wants, just like salting a food.

“I would never have called myself a daiquiri fan before,” says new daiquiri enthusiast Dr. Rebecca Whelan. “I harbored bad associations of the drink as tending toward the overly sticky and sweet, relying on flashy color to mask poor quality and craft. The daiquiri [at Cleveland’s Spotted Owl] is impeccably balanced and complex. The presence of lactic acid in the lime juice is unlike anything I’ve experienced in a cocktail before, and it works perfectly, with layers of flavor that are both bright and deep.”

Of course, if bartenders are doing it right, you may not notice that your lime has secretly been replaced by a special mixture of acids. The trick is mimicking the natural acid balance of a fruit, enhancing rather than distorting the harmony of the drink, and working within our expectations of what a properly balanced drink is.

Most of the bartenders interviewed for this story have been playing around with isolated acids (citric acid at least) for a few years, inspired by recipes found online or trips to the home-brew store. For many, the publication of Dave Arnold’s book Liquid Intelligence in 2014 moved their experiments forward, as Arnold printed his recommended blend of acids—not just citric—to emulate lime juice. This technique has allowed bartenders to make better batched cocktails and clarified juices.

THE PROBLEM WITH ORANGES

At many cocktail bars, the old-fashioned has rocketed in popularity over the last few years. Classically made, it contains just whiskey, bitters, and sugar and gets much of its character from an aromatic garnish of orange peel. That popularity has a side effect: Dozens of oranges daily are stripped of their zesty peel, leaving a surplus of orange juice, which bars have little use for. The juice of the orange is very rarely called for in either modern or classic cocktails, because it isn’t nearly as acidic as lemon or lime juice and can make drinks turn out flabby and watery. Many bars end up discarding the peeled oranges entirely, but increasingly, some venues are acid-jacking the juice instead—dissolving in small, precise amounts of pure versions of the same acids that are in lime juice, to give that sweet fresh orange juice the strength of lime.

Nick Detrich did that when he developed drinks at Cane & Table in New Orleans: “Since we use a great deal of orange peels, but not much juice, we have two cocktails on our happy hour list that use an ounce and a half of orange juice and we wanted to balance the pH on those drinks. We use a blend of malic and citric acid because the green apple Warhead [candy] qualities of the malic add a nice vibrant freshness that is a great counterpoint to the very drying citric. We experimented with tartaric acid as well, but it added a weird dustiness.”

The Blood and Sand is one of the few classic cocktails that requires orange juice, and as a result it’s widely considered a challenging or unbalanced drink. Nick Kennedy of Civil Liberties in Toronto makes his with orange juice he spikes with citric and malic acid, just as Detrich does, changing his ratio of acids depending on the seasonal sweetness of the orange juice and tasting it against the acidity of lemon juice.

At Momofuku Ko in New York, Channing Centeno added citric acid to the house grapefruit syrup and to orange juice so he could avoid having to include limes. He says, “Instead of adding a half-ounce of lime to an already seven-ingredient drink to brighten a cocktail, why not just fortify the acidity in one of the existing ingredients?”

At Cassia in Santa Monica, California, Kenny Arbuckle deconstructs and reconstructs oranges by blending orange peels and juice together, removing the solids from the peel, then adding citric and a touch of phosphoric acid. “The point of acidifying the OJ,” he says, “is so we don’t have to add another acid, like lemon or lime, that would alter the flavor of the drink.” Of course, it’s not the exact same juice anymore. Arbuckle says, “The acidified OJ is texturally smoother, as the pulp is removed with the solids. It has a much sharper acidity than typical citrus. The flavor is still very orangy—part of the point in using the oil in the peel. The blending of the peels into the juice helps keep the flavor.”

FRANKENFRUIT

But why bother hand-building acidity to imitate limes when you can buy limes all year round? One issue is that lime juice begins losing its fresh flavor as soon as it’s squeezed, and a cocktail made with yesterday’s juice tastes stale. This is especially pronounced in the wake of another trend that’s sprung up within the last few years: In order to speed up service at craft cocktail bars, some bartenders are premaking their cocktails and putting them into bottles and kegs. They initially focused on citrus-free drinks, like the Negroni and the gin and tonic, but soon started seeking ways to bottle citrus-based cocktails without relying on temperamental citrus juice.

Cameron Brown of the Fairmont Pacific Rim Hotel in Vancouver, British Columbia, Canada, has made large batches of cocktails in advance for events, using an acid blend instead of citrus juice, since he wouldn’t be able to squeeze enough fresh juice the same day (and wouldn’t want to use oxidized juice from the previous day). His recipe calls for citric and malic acid with just a drop of acid phosphate.

Brown says, “The citric gives you the up-front acidity, but lacks the pucker feeling I need from malic on the back end. The acid phosphate rounds out the back end and creates a nicer texture and mouthfeel.” To compensate for the lack of actual juice, he says, “I tend to express some kind of citrus oil on top of the drink.”

Aaron Polsky of Los Angeles’ Harvard & Stone makes kegs full of cocktails using “the Dave Arnold recipe of 4 percent citric, 2 percent malic, 0.04 percent succinic” to simulate the acidity of lime juice for batched kegged cocktails for festivals and bars. Polsky then adds a custom-made combination of makrut (kaffir) lime oil and distillate—concentrated, isolated lime flavor—to the acid mixture to make a stable lime juice substitute. Not only will this formula not degrade over time, but it allows him to control the amount of water in his citrus mixture, depending on the final use of the drink (he says this is handy for making snow cones, where you want limited water content), or make a flavored cordial or sour mix of sorts from it.

ALL OF THE ACID, NONE OF THE JUICE

Other bartenders use added acids to achieve high acidity without any citrus taste, real or imitated. Alex Riddle of Roka Bar in San Francisco makes a cocktail that includes buckwheat shochu (a Japanese distilled spirit), squid ink, and white truffle oil, plus citric acid. He says, “We wanted the emphasis to be on the deep savory and umami flavors. It needed some sort of acid to balance the richness of the truffle and shochu. I originally tried using lemon juice, but found it to be both too full and too recognizable a flavor, ultimately taking away from the nuance of the other ingredients. We settled on a 7 percent citric acid solution, which provided enough acid to balance the cocktail, but was also simple and unassuming enough to allow the main components to shine through.”

Vlad Novikov of the Elixir Lounge in Chicago uses a clear sweet-and-sour mix of sorts, combining citric, ascorbic, and malic acids, without a citrus flavor. He says of his combination, “Adding malic acid helps dissociate the flavor of lemon that people get from citric acid sometimes, and adds a little depth.” At first, he says, he used chemical acidity constants (pKₐ) to calculate the exact theoretical amount of citric, malic, and ascorbic acids to replicate a specific citrus juice, “before realizing it was easier to just use my mouth to measure.”

Jacques Bezuidenhout of Forgery in San Francisco uses acid phosphate (a solution based on phosphoric acid) to replace lemon juice in a version of a Vampiro cocktail that includes crème de cassis. He says, “Lemon juice really muddied up the color of the cocktail and dominated some of the delicate flavors, so the acid phosphate added the desired acid to balance out the cocktail, allowing it to retain clarity in the glass.”

A LACTIC COLLABORATION

At the Spotted Owl in Cleveland, owner Will Hollingsworth adds lactic acid (a flavor we associate with fermentation, particularly fermented milk) to lime juice, which gives the bar’s popular daiquiri what he calls “creaminess” as well as changing the perception of the drink’s acidity.  

To develop the drink, Hollingsworth worked with Dr. Rebecca Whelan, who is a regular customer as well as an associate professor and chair of chemistry and biochemistry at Oberlin College. Whelan says, “One evening when I was enjoying a cocktail at the Spotted Owl, he asked for my help interpreting a peer-reviewed research report. At the heart of the paper were observations about different acids in beverages and how those acids are perceived.” On the back of a Spotted Owl menu, Whelan and Hollingsworth wrote out chemical formulas to come to an understanding of what exactly the researchers had discovered.

“Her guidance on our daiquiri was invaluable,” says Hollingsworth. “Because of the particular anionic pairing of citric acid and lactic acid, the addition of a dash of lactic acid to the lime juice has the effect of actually raising the pH of the lime juice (from 2 to about 2.5), making it less acidic in absolute terms.” However, lactic acid also interacts with the drinker’s saliva, making the drink feel more astringent, “making it less viscous, and thus increasing a drinker’s perception of acidity. So despite the fact that in absolute terms, the lime juice is becoming less acidic, it’s being perceived as having a deeper sourness than it otherwise would have.”

SEARCHING FOR CLARITY

In a cocktail with carbonation, any particles of fruit pulp will turn it into a frothy mess, so some bartenders have become obsessed with getting out all the solids from juices.

When high-tech bars use centrifuges to clarify juices, the pulpy solids are removed, which can reduce the juice’s acidity. Judicious reacidification through the addition of various powdered acids can bring them back to their original levels of sourness.  

At Midnight Rambler in Dallas, Chad Solomon uses a centrifuge to clarify all the fresh ingredients that go into his carbonated beverages in order to reduce bubble-killing nucleation points.

Solomon says, “The clarification strips down the fresh ingredient to a leaner, cleaner version of itself that is still brimming with aroma. The clarified product is then enhanced with acid and [fructose or sucrose] to enhance flavor and mouthfeel.”

His imagination was sparked when he first saw Dave Arnold make a carbonated gin and tonic (pre-centrifuge) around 2007. He was further inspired by Darcy O’Neil’s book Fix the Pumps, which discusses alternative acidulants in the context of the soda fountain.

Solomon chooses which acids to use based on “the composition of the fresh ingredient as well as relative astringency, to properly enhance flavor and mouthfeel. I like to employ citric acid where the predominant acid is citric acid, such as orange, grapefruit, lemon, lime, pineapple, mango. For apricot, peach, pear, strawberry, apple, and watermelon, use malic acid. Tartaric or fumaric acid should be employed for grape, cherry, and banana.” He also supplements those acids with small amounts of phosphoric acid “for its flavorless, bone-dry astringency, to enhance mouthfeel.”

At Chicago’s The Aviary, Micah Melton uses a blend of acids in many of the drinks on the menu, both for carbonated cocktails and, in some cases, just to achieve a particular taste. “We just did a hot sauce-passion fruit clarification . . . it looks like champagne and tastes like ^%$**@$^@$*!!!!!,” he writes. He uses at least two acids per clarified fruit, to vary the effect; typically citric acid and one other, such as tartaric acid to give a “green grape” note, or fumaric acid for its “softer apple-like acidity.”

ACID TESTING

[Ed note: After Camper English delivered his story to the Cook’s Science team, senior editor Paul Adams began developing his own acid-hacked cocktail recipes for the home cook. The following is from his perspective.]

Back in the test kitchen, we were curious to give these acid-hacked cocktails a try. We started by tasting the various acids on their own, dissolved in water solutions, to get a feeling for their different characters. Citric acid had a medium impact and a puckery, drying finish. Malic acid tasted much stronger, with a hint of tart green apple—“like a Warhead candy,” noted one taster. Ascorbic acid was the mildest tasting and tartaric the strongest, also featuring a “creamy” taste. Succinic acid was the worst, tasting like some acutely bitter inedible resin or mineral. That must be why it’s only used in tiny doses. And the tasting notes on lactic acid—which we all love when it shows up in pickles and yogurt—included “bitter,” “like Fernet,” and “hint of bile.” Tasting acids neat is definitely not the most pleasant way to experience them, but it’s educational.

Next, I set out to do what seems like a natural starting point for hacking cocktails with powdered acids: tweaking other juices to give them the same acidity as lime juice. Flavorful and versatile, lime contributes more complexity than lemon juice and shows up in many cocktails. In his remarkable book Liquid Intelligence, which played a significant role in spreading the acid gospel, Dave Arnold gives a formula for conferring lime acidity on orange juice: For every liter of OJ, dissolve in 32 grams of citric acid and 20 grams of malic acid.

I squeezed a bunch of oranges and tried the recipe. The orange juice’s fragrance was unchanged, and it still had the round sweetness of fresh OJ, but at the same time it had the mouth-puckering bite of lime! Arnold also recommends adding a fraction of a gram of succinic acid, to create a more realistic simulation of the actual acid balance in a lime. When I mixed in the tiny quantity of succinic acid, it added an additional sharp tartness on the tip of the tongue that perfectly completed the lime effect.

I used citric, malic, and succinic acids, in various proportions, to make lime-acidified versions of grapefruit juice and apple juice as well, and then I started mixing them into cocktails.

A vast number of classic cocktails call for lime juice, so it was easy to find uses for my new lime substitutes. I put lime-adjusted orange juice in a margarita, lime-adjusted grapefruit juice in a daiquiri, lime-adjusted apple juice in a Jack Rose variant. In every case, the acid-adjusted juice did its job of lending the drink bright acidity, but also contributed some of its own fruit character.

After a delightful video conference session in which the Boston kitchen crew mixed and tasted cocktails while I supervised from my New York couch, we settled on two favorites: the Creema di Leema, a friendly, frothy cocktail using gin and acid-adjusted orange juice along with vanilla and cream; and the French 56½, made with gin, lemon, and soda, with tartaric and lactic acids added to give the impression of a sparkling wine.

Devising cocktails with acids as freestanding ingredients, rather than in the somewhat familiar form of simulated lime juice, turned out to be unexpectedly difficult. When a trial mixture tasted not quite right, I could tell it was out of balance, but it was strangely tricky to tell whether it needed more or less acid! Especially when lactic and tartaric were involved. More than once I was sure a recipe needed less acid, but when I made a reduced-acid version, it tasted wrong; and when I made a version with increased acid, suddenly everything came into balance.

With the addition of brand-new fundamental ingredients like these to the pantry, it’s necessary to play around to develop a real sense of them. Like being able to hear whether an out-of-tune note is too sharp or too flat, the ability gets better with practice.

GETTING STARTED WITH ACIDS

Here are a few pointers to help you start learning the acid ropes in your home kitchen or bar.

Get yourself a high-precision scale. The kitchen scale you have can only measure in increments of 1 gram, or perhaps 0.5 gram. Which is great for most cooking, but with these ingredients, a little is all you need—and you want to be able to measure that little precisely. The difference between 0.1 gram and 0.2 gram can make a big difference. You can get a good pocket-size scale for less than $20.

Start with a small selection. Citric acid and malic acid make a good starter kit: They’re common, affordable, versatile, and last but not least, they dissolve easily. Add straight citric for lemony acidity, straight malic for Granny Smith acidity, and a 2:1 citric-malic blend to emulate lime.

Taste them in sugar. To get to know your new acids, you’ll want to sample them, but not straight—too sour! You can mix them into water, but white sugar is a nice alternative that showcases each acid’s character. Mix 3 grams of a powdered acid (or combination of acids) into 100 grams of white sugar, then taste.

Swap them in. Try replacing lemon juice in a recipe with citric acid. Lemon juice is a solution of about 5 percent citric acid, so you can mix up faux lemon juice by dissolving 5 grams of citric acid in 100 grams of water. Then use it ounce-for-ounce in place of juice.

Styled food photography by Steve Klise.

Test kitchen photography by Kevin White.