Episode 006 - Citrus Crash Course

Hey everybody,

Welcome back to another episode of the Modern Bar Cart Podcast!

I’m your host, Eric Kozlik, and I’m coming to you today with another Bar Cart Foundations episode. That’s right, these are the episodes that lay the groundwork for all the discussions we have with our excellent and truly knowledgeable guests as we chat about cocktails and home bartending.

Today, we’ll acquaint ourselves with the magical world of citrus in all its tart, tangy glory.

Most people are familiar with the use of citrus in their favorite cocktails, whether that’s the orange peel garnish in your Old Fashioned, the squeeze of lime in your Mojito, or the pucker of lemon in a classic whiskey sour.

But have you ever stopped to think about why we put citrus in our drinks? What role does it play? What would cocktails taste like without it?

I’m gonna begin today by taking you through the history and science of citrus, and then give you some excellent bar hacks to help you bring your citrus game to the next level. Specifically, we’ll talk seasonality, how to select your citrus, and best practices for peeling and juicing.

In July of 2016, I had the privilege of attending a really fascinating seminar at Tales of the Cocktail down in New Orleans called, “From Grove to Glass: Citrus Complexity.” And it was in this seminar that my eyes were opened to the sheer variety of citrus available on today’s market.

Think about it. Off the top of your head, you can probably rattle off eight or ten varieties:

There’s lemons, Meyer Lemons, Limes, Key Limes, Navel Oranges, Mandarin Oranges, White Grapefruit, Ruby Red Grapefruit, Tangerines, and Clementines, just to name the commercially popular ones here in the U.S.

But like most modern produce, today’s citrus is the result of centuries of careful breeding and genetic tweaking, selecting for the most desirable citrus traits like size, juiciness, sweetness, roundness, color—basically any feature that will make you pick up an attractive-looking fruit, eat it, say, “dang, that was tasty,” and purchase several more on your next trip to the market.

Several thousand years ago, though, we didn’t have all these fancy, beautiful fruits. All we had were the Pomelo, the Mandarin, the Citron, and an even more obscure fruit called the Small Flowered Papeda. Pretty much any citrus on the market today can be traced back to some combination of these genetic ancestors.

Geographically speaking, most of these varieties originated in China or elsewhere in Southeast Asia and gradually made their way to other parts of the world, especially as different varieties were developed and became popular. So, in terms of the vast sweep of natural history, or even the history of humankind, citrus fruits are a relatively new phenomenon in most parts of the world.

In her book, The Drunken Botanist, Amy Stewart observes:

As impossible as it may be to imagine the Mediterranean and North Africa without its citrus trees, Arab traders brought the sour orange, the lime, and the pomelo to the region only eight hundred to a thousand years ago. The sweet orange came only four hundred years ago, when Portuguese traders carried it back from China. By this time, citrus was moving all over the world.

And she’s right. Citrus played a really key role in the explosion of shipping and world-wide commerce that evolved as a direct result of the age of exploration—it literally kept early European sailors alive as they criss-crossed Atlantic and Pacific trade routes and built vast empires.

Today, of course, we know citrus as a rich source of Vitamin C, but back in the 17th and 18th century, people weren’t really aware of vitamins or micronutrients and their role in keeping us healthy.

This all started to change when British physician James Lind began conducting controlled experiments with the diets of sailors in the Royal Navy in 1747 and found that those who ate a diet that included fresh citrus fruits tended not to suffer from scurvy, a disease that killed an estimated 2 million sailors in the sixteenth through eighteenth centuries.

Now, even though the Royal Navy didn’t really buy Lind’s citrus theory, the famous naval Captian James Cook was all about it. And on his epic voyage to the South Pacific from 1768-1771, he loaded his ship with citrus and the other foods recommended by Lind for a healthy nautical diet, and he didn’t lose a single sailor to the notorious disease.

But what were the implications of this newfound anti-scurvy regimen?

Well, simply by virtue of its role in keeping sailors alive, citrus began popping up in ports all over the world, becoming available in areas of the New World almost as quickly as Europeans could colonize them.

Another implication was that sailors and the companies who sponsored and managed their trade expeditions were able to experiment with the best ways to consume their citrus, and these experiments resulted in some of the most famous cocktail precursors—notably, grog and punch. Almost every recipe for these drinks relies heavily on the presence of citrus, and that is a tradition that continues to exert its influence over the cocktails we enjoy to this day.

So, now that we know a bit more about where citrus comes from and how it made its way behind the bar, let’s step out of the history classroom and into the flavor lab to figure out what these fruits add to our drink, and how the magic happens.

First, we’ll look at the anatomy of a citrus fruit and define some vocab terms that we’ll return to as we discuss cocktail-related applications.

The outermost part of a citrus fruit is the peel (or “zest”), which contains small pores where the essential oils are stored, which are referred to as “glands.”

Beneath that, we have what’s called the pith, which is the spongy, astringent, and relatively flavorless layer that separates the peel from the flesh. This is often what partially remains when you peel an orange, and the amount of pith in a given citrus variety or individual fruit can vary based on any number of factors, including soil quality and meteorological growing conditions.

Beneath the pith is the flesh of the citrus fruit, which is where the tangy juices are stored. The flesh is most often divided into segments that radiate out from a common center, and these segments also contain the seeds of seeded varieties.

Most often, it’s the innermost and the outermost parts of a citrus fruit that are used when making cocktails (or cocktail ingredients like bitters and liqueurs)—the juice and the peel. And these two parts of the fruit are often used for drastically different purposes, which can be boiled down to the difference between flavor and taste.

See, what most people don’t know is that flavor and taste are very different. Taste deals with the taste buds, which can sense sweet, sour, salty, bitter, and savory compounds, whereas flavor deals with aroma, and the way our scent processing (or “olfactory”) system fuses scent compounds with taste sensations to build a whole flavor picture in the brain.

Because citrus juice is packed with acidity, it stimulates our taste buds. And because citrus ZEST contains a ton of volatile aromatic compounds expressed in the form of essential oils, it activates a whole slew of receptors in the olfactory pathway, which is the responsible for flavor perception.

The word “acid” comes from the latin word acidus, meaning “sour.” And so, even though there are a ton of other characteristics of acids, chemically speaking, it’s clear that this “sourness” was probably the earliest recognized and certainly remains the most important when it comes to food and drink.

The most common type of acid found in citrus fruits is Citric Acid, and this is what’s known as an “aqueous acid,” meaning it’s easily dissolved in water, forming an acidic solution. So when you taste lemon juice, what’s happening is that the citric acid molecules dissolved in water activate taste receptors on your tongue. The result is that pleasant (or perhaps unpleasant if the drink’s not made well) tangy taste you get when you sip on a Margarita or a Whiskey Sour.

Citrus oils are sort of the opposite when it comes to how they react with water. As we all know, oil and water don’t mix, and so the flavor compounds found in the citrus peel are used very differently in cocktails.

There’s basically two approaches. The first is to use a non-water solvent (like alcohol or glycerine) to extract the flavorful oils from citrus peels. This is the case with bitters, vermouths, and liqueurs. What happens is that the alcohol in these products literally sucks the oils out of the peel, and incorporates them into the flavor profile of the end product. Generally speaking, the more ethyl alcohol the mixture contains, the more powerful the extraction will be, resulting in an extremely potent end product. That’s essentially “Bitters 101.”

The other common way to use citrus peels in cocktails is to employ their aromatic properties as a garnish. For example, in an Old Fashioned, an orange peel is generally “expressed” over the top of the glass by squeezing the orange peel over the cocktail and rubbing it around the rim. The same is true of the lemon peel garnish in the classic gin martini, and most bartenders have a fierce stance as to whether the peel should be left in the glass as a garnish, or simply expressed and then discarded. Honestly, it’s a matter of taste

Again, because oil and water don’t mix, what happens is the volatile scent compounds in the peel coat the rim of the glass and float on the surface of the drink, giving an incredibly fragrant flourish every time you take a sip. In this sense, garnishes aren’t just there to look pretty--they also play an important role in the overall flavor experience of the cocktail.

Sometimes you’ll even see flaming citrus garnishes, where the bartender will activate the citrus oils with a lighter (usually with an orange peel), and then express those oils over the flame, showering the top of the cocktail with a slightly burnt version of the traditional citrus oil flavor. It’s a really nice parlor trick because it results in a nifty little fireball, especially in a dimly-lit setting.

But PLEASE NOTE: this is a top-level garnish move, and it definitely falls into the “don’t try this at home” category, at least as far as our podcast liability policy is concerned.

So, now that you know more about the history and science of citrus than 95 percent of people out there, it’s time to kick you into the top percentile with a few excellent bar hacks that will help you seriously optimize your cocktail-making (and drinking) experience.

Let’s start right at the beginning with your trip to the grocery store or market where you’ll select and purchase your citrus.

The first thing that many people don’t know is that, at least here in the Northern Hemisphere, citrus is a WINTER fruit. Which is to say citrus fruits become ripe when most of us in the continental U.S. are breaking out our cold weather clothing. And yet, somehow we associate the taste of citrus with summer beverages like Lemonade, Margaritas, and Mojitos.

What are the implications of that?

Well, for starters, you’re generally going to see lower citrus prices between November and March than you’ll tend to see at other times throughout the year. So if you’re a bargain hunter, winter is the time when you should think about busting out your citrus-heavy concoctions. In fact, making a large bowl of citrus-forward punch is an excellent way to use the seasonality of citrus to help you impress your holiday guests with a pre-batched drink that leaves you free to mingle.

But let’s say you rush off to the grocery store to take advantage of these great seasonal prices. What happens when you get there and are faced with a mountain of lemons or limes? How do you know if they’re ripe? How do you know you’re selecting the fruits that’ll give you the most bang for your buck?

A couple pieces of info here to help guide your selection:

First off, the squeeze test rarely fails. If you pick up a piece of citrus and it’s hard as a rock, you’re probably not going to get a whole lot of juice out of that particular fruit. So, if you’re making cocktails that require a lot of citrus juice, go for softer fruits.

Secondly, take a look at the nature of the citrus peel. If it’s rough and bumpy, chances are it was picked a bit prematurely before the fruit could take on enough water to swell and stretch out the peel. On the other hand, if the peel is smooth and the pores (or oil glands) are spaced a bit further apart, chances are you’re dealing with a riper fruit.

Do you look like a bit of a maniac digging through a pile of limes, squeezing them and looking intently at the pores? Yes. But these are the sacrifices we make for our cocktails.

So, you’ve arrived home with your citrus trove. Where do you store them?

If your first thought is “in the refrigerator,” then think again. Unless you’re planning on waiting over a week to use your lemons, limes, or grapefruits, there’s really no reason to refrigerate. Think about how they were displayed at the market. Just hanging out at room temperature like the onions and potatoes. So why should the get special treatment in your home?

In fact, there’s a very simple reason why NOT to refrigerate your citrus—room-temperature fruits are easier to juice than cold ones.

Now, when it comes to the AMOUNT of juice in each fruit, this is where things can get a bit dicey—or at least inaccurate. The amount of juice you can extract depends on a number of variables, but there are a couple things you can do to optimize your output.

  1. If you’re dealing with cold citrus, stick it in the microwave for ten seconds to get the juices flowing. 

  2. Before you cut into the fruit, give it a nice, firm roll on the counter to mash up some of the flesh on the inside. This makes it a bit pulpier and annoying to slice into with a paring knife, but it really increases the amount of juice you can get.

  3. Use a citrus press—plain and simple, this is the best way to juice your citrus unless you have access to an industrial juicer. For more on citrus presses, check out episode 2, which is our foundations episode on bar cart hardware.

  4. After you think you’ve gotten all the juice out of a half a lemon or lime, think again. When I’m juicing limes, for example, I re-juice every three lime halfs by reloading them into the citrus press in their flattened state. The can yield anywhere between an extra third- to half-an-ounce of juice, which is not insubstantial. And the reason it works is because with all those mostly-exhausted fruits piled into the press right next to one another, they don’t have enough room to flatten out, and they give up the last few drops of juice they managed to escape with the first time.

Again, do you look a little crazy trying to squeeze juice out of already-juiced limes? Sure, right up until the part where you actually get more citrus juice. Remember, excellence always makes people uncomfortable.

Now comes the part where you have to beautify your citrus juice before using it in a cocktail, and this part isn’t always necessary, but it really improves the appearance of the drink. And when I say “beautify,” I simply mean straining out the pieces of pulp that managed to sneak in during the juicing process.

If you’re making a single cocktail, this can easily be done by filtering your citrus juice through a small, fine-meshed sieve when you add the citrus juice to the shaker or mixing pint with the other ingredients. Easy fix, problem solved.

But what about if you’re juicing a TON of citrus for a large format cocktail or punch? Having found myself in that situation many times, here’s my bar hack.

I start with a large, non-reactive plastic mixing bowl so that I don’t have my acidic citrus juice sitting in a metal container. Into that mixing bowl, I place a large, fine-meshed strainer—the kind you use for culinary purposes. When pressing my citrus, I make sure the juice goes through the strainer and then into the bowl, which usually removes at least 90% of the pulp. That’s usually just fine for a bowl of punch, but you can always do a second pass through a little cocktail sieve if you really want to. This method is extremely useful for lemons, which tend to have more pulp and seeds to contend with than limes do.

Now for my citrus peel hacks:

This first one is going to sound a little extreme, but there’s actually a really big difference in the structural resilience of lemon peels and orange peels, which are the two types most commonly used for expressed garnishes. Even when you slice them really thin, orange peels will usually hold up to twisting and squeezing pretty well. Lemon peels, on the other hand, tend to snap in half when you express them unless you’ve got a bit of pith on the back. Honestly the only way to learn this is practice, and the only way to get a good, consistent peel that you like is to try out different peelers and use different amounts of pressure as you peel.

What happens if you need a bunch of peel garnishes, but you don’t have time to peel them all at the time the cocktails are constructed? One simple solution is to peel ahead of time and to store the peels in a plastic bag in the fridge wrapped in a moist paper towel. This is good for only a few hours, but those few hours can be a life saver if you’re making a lot of cocktails, allowing you to do some prep work ahead of time.

My last peel hack is a cocktail ingredient recommendation. The ingredient is called Oleo Saccharum (literally “oily sugar”), and you can make this at home by peeling two lemons into a tupperware container and then coating the peel with a generous amount of white table sugar. Muddle the sugar and the peels together and then let them sit for a few hours on the counter. When you come back, what you’ll find is a syrupy substance that is essentially a combination of the sugar and the essential lemon oils

Oleo Saccharum has a lot of applications in traditional punches, which you can find recipes for in David Wondrich’s book, Punch. But it’s also fun to play around with this ingredient as you experiment with your own cocktail recipes as well.

So there you have it—from the store to the cocktail glass, you’ve now got a full arsenal of bar hacks to help you take your citrus game to the next level.

But it would be a bit cruel of me to take you all this way without giving you a few of my favorite citrus-forward cocktail recipes.

The Daiquiri

Let’s start with a simple, easy-to-learn classic called the Daiquiri, which is a light, summery cocktail that’s incredibly easy to make and super refreshing.

The ingredients are:

  • 2 oz White Rum
  • 1 oz Lime Juice
  • ½ oz Simple Syrup

Combine these ingredients in a cocktail shaker with ice, give it a good, healthy shake, and then strain the cocktail into a coupe glass to enjoy.

The Sidecar

Another great citrusy cocktail is the Sidecar, which has two types of citrus involved, representing both the citrus juice and the essential oils.

The ingredients for the sidecar are:

  • 2 oz Cognac or Brandy
  • 1 oz Orange Liqueur (Cointreau or Grand Marnier)
  • ¾ oz Lemon Juice

Shake all these ingredients over ice, and serve up in a cocktail glass (sugared rim optional).

The Last Word

Finally, I’ll leave you with the advanced option--my favorite cocktail of all time--The Last Word. This is a funky, challenging, and really intriguing cocktail that uses equal parts of all ingredients:

  • 1 oz gin
  • 1 oz Green Chartreuse
  • 1 oz Maraschino Liqueur
  • 1 oz lime juice

Combine all these ingredients in a mixing pint with ice, and stir until well mixed and chilled. Then strain into a cocktail glass and enjoy without any garnishes or adornments.