In my previous set of articles I’ve already talked about the effect sugar, acidity, alcohol and bitterness has on the texture of a cocktail. This article will examine other sources of texture, mainly dairy, eggs, and carbonation.
Raw milk, warm from the cow – and yes, we’re going to talk about cow milk here instead of sheep, goat or camel -- is an incredibly complex solution of microscopic fat globules, sugars (namely lactose, a complex sugar made from glucose and galactose), vitamins, white blood cells, and water. Some breeds of cow are less efficient at converting the yellow pigment carotene into Vitamin A, so their milk is more golden in color (interestingly enough, goats, sheep and water buffalo are 100% efficient, so their milk and cheese are always starkly white). Raw milk is also full of bacteria, some of which are responsible for the conversion of lactose to lactic acid (souring), and some of which can be harmful to humans (Salmonella and E. Coli O157:H7, among others). Milk is slightly acidic, at around pH 6.5-6.7.
Raw milk is routinely pasteurized in this country, which kills white blood cells and bacteria, but also deactivates naturally occurring enzymes and drives off fresh milk aromas, replacing them with other aromas and flavors depending on the type of pasteurization used. The most common ways to do this to milk are Low Temperature/Long Time (LTLT), where milk is held at 145 degrees Fahrenheit for 30 minutes, High Temperature/Short Time (HTST), where milk is brought to 161 degrees Fahrenheit for 15-20 seconds, and Ultra High Temperature (UHT), where milk is heated to 275 degrees for one second. LTLT milk tends to develop green notes and a slight sulfury smell (which Americans now prefer – they disliked early pasteurized milk). HTST develops almond and vanilla notes. UHT milk can be stored at room temperature, but tends to taste flat and sterile. Light is dangerous to the aroma and flavor of milk, leading to metallic, fishy, or paint-like aromas… you should always buy milk in opaque cartons.
Milk is also homogenized in the United States. Homogenization takes hot milk and forces it through fine screens under pressure, which shears fat globules, making them smaller and yet increasing their total surface area. This depletes the usual protective coating of phospholipids that stop the fat globules from clumping together, and casein (a milk protein) steps in to do the job. Casein-laden fat globules are heavier than normal, and do not interact with each other, so the fat does not rise to the top of the milk as cream.
Whole milk is about 3.5% fat (again, some breeds give more, some less), and it is common to see 2%, 1% and “skim” milk (between .1 and .5%) in American grocery stores. American cream is usually between 36%-40% milkfat, and is almost always UHT treated, which reduces whipping ability.
Speaking of milk foams, it is relatively easy to whip cream above 30% fat into stable foam in a cocktail shaker. The agitation of milkfat traps air in a relatively sturdy layer that takes on a new, more solid texture. The best way to achieve this is to take the spring off a Hawthorne strainer and drop it into the shaker, add cream and dry shake hard for at least 30 seconds. Remove the spring, and scoop whipped cream out.
Milk will curdle when its pH reaches 4.6, so cocktail makers beware: too much acidity without anything else to buffer it will curdle your drink. This can be used to good effect if you’re making milk punch: Adding milk to an acidic punch base will curdle the milk, which can be strained out of the punch, leaving whey proteins and lactose behind to soften the drink.
Dairy increases cocktail texture two ways. First, fat in milk coats the mouth, lending richness. Too much fat, though, and flavors and aromas become muted. Secondly, lactose in milk is a sugar, and from previous articles, sugar increases texture.
Now let’s talk about eggs, which are another ingredient which seem simple, but are staggeringly complex. Both the white and yolk of an egg are mainly water and protein, but of very different types. Egg white proteins are mainly ovalbumin and ovotransferrin, which provide nourishment for the chick and bind iron. Ovotransferrin is interesting because it sets when foamed, which we’ll look at a bit later. Egg yolks on the other hand are still mainly water, but have 6 grams of fat, a lot of cholesterol, and an interesting chemical called lecithin, which is a powerful emulsifier. Emulsifiers are important because they help bind ingredients that would normally separate from each other together.
Egg whites lend less texture to cocktails than egg yolks. Egg whites are typically used to provide a foamy head (a meringue) on the top of cocktails. Unlike dairy foams, egg white foams are lent structure by protein, though like dairy foams, egg white foams are ephemeral. These foams form as ovotransferrin molecules are forced out of their shape and link with each other, trapping tiny air bubbles and water films. Ovotransferrin has parts that are hydrophilic and parts that are hydrophobic – they’re great at joining two things that would normally want to come apart. But given enough time, sulfur-hydrogen bonds in some of the egg white proteins break apart and form sulfur-sulfur bonds, which end up forming tight linkages which effectively squeeze the water out of the protein matrix. Foams weep, then destabilize.
There are a few important ways to increase the stability of egg white foam within the realm of cocktails. First, a lower pH environment inhibits the breakup of S-H bonds, which is why cream of tartar speeds foaming. This can be as little as ½ teaspoon of lemon juice per egg white if it’s added when you start the foaming process. Sugar added at the beginning of foaming slows down the process initially, but increases the viscosity of the water phase of the foam, slowing weeping. Finally, some water helps speed the foaming process, but care must be taken here – adding more than 40% of the volume of the egg white inhibits foaming entirely.
Of course, there are also things that will make your egg foam fail: The chief among these is egg yolk (or any fat, really), which competes with proteins for space in the matrix without adding any structural support. The other is detergents, so make sure your tools and shakers are clean!
Finally, let’s talk about carbonation, which is usually in the form of sparkling wine source, club soda, or tonic water. Carbonation does two things to lighten the texture of cocktails. First, it physically lightens the texture of the drink, in the same way that a soufflé tastes lighter than the raw batter from which it’s made. Secondly, carbon dioxide disassociates into carbonic acid, which lowers the pH of the cocktail. Low pH means less texture. Third, the addition of water at zero proof lowers the overall alcoholic strength of the drink, which decreases its texture.
|2||oz||Old Tom Gin (or Plymouth)|
|3||dr||Orange flower water|
|2||dr||Vanilla extract (very optional)|
So how do we actually go about making cocktails with a particular texture? The fat inherent in milk tends to overwhelm cocktails, flattening them out. Milk as a texturant is difficult, as the milk becomes the center around which the remaining ingredients are built, as in the Absinthe Suissesse. Adding milk to a Negroni to get a richer texture is not a good idea! Egg yolks also are difficult to work with unless they’re the star attraction. Like milk, the fat in an egg yolk dominates the flavor profile of any cocktail that uses them – think about all the variations of the flip that have dark rum, demerara syrup, or allspice dram in them. Egg whites are more neutral, and their naturally sulfury aroma can be masked by dashing bitters (or another aromatic) on top of the meringue. It is still much easier to use simple syrup or higher proof alcohol to increase cocktail texture.
If cocktails need to be leaner, carbonation is a good way to go, as it affects texture three ways. Acidity is the next best way, though they impart their own set of flavors. Lactart is incredibly useful here – not only is it powerfully acidic, but it has almost no flavor, so it can de-texturize drinks without changing the flavor profile. Some wild people put their cocktails though an ISI whipper to nitrogenate them, which makes for finer bubbles without the acidity and prickle associated with carbonation.
A classic example of a drink with dynamic tension from milk, sugar, egg, acidity and carbonation is the Ramos Gin Fizz. There’s a delicate balance here to keep the acidity high enough to lighten the drink without curdling the milk, and the egg, carbonation and long shaking time make for an ultrafine texture. I think someone ought to put a Ramos into an ISI whipper and foam it into a glass, to see if the texture is similar to a long-shaken one. Perhaps someone would like to take that project for extra credit.
P.S. If you’d like to learn more about how ingredients work, I can’t recommend “On Food and Cooking” by Harold McGee enough. It’s not a cookbook, but you’ll learn a lot.
This is the second in a series of advanced cocktail construction tutorials by Kindred Cocktails editor, Zachary Pearson.
Want the introductory series? Start with acidity.