8. Using Acidity

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Acidity is one of the most important concepts in understanding flavor, and knowing how to use it is crucial to cooking well. As we’ve discussed before, the term “seasoning” in cooking generally refers to the use of salt and acid to build and balance flavor in food. You can almost think of salt and acid as two sides of the same coin— they both help to elevate existing flavors in food, but they have different effects and are used a bit differently.

Knowing how to properly use acid will elevate your cooking substantially— it’s one of the most important skills you can develop as a cook. In this lesson we’ll cover what acidity is, why it’s important, and how to use it in your cooking.

Scientifically speaking, an acid is a substance with a pH below 7. Things that are acidic taste sour or tart, and there are a ton of them that we commonly use in cooking. Lemon juice, lime juice, vinegar, tomatoes, tomato sauce, yogurt, buttermilk, and wine are all acidic ingredients.

Acidity is one of the five major flavors, along with sweetness, saltiness, bitterness, and umami. But acidity isn’t just a flavor, it’s also a tool that’s used to brighten and balance other flavors, which is why it’s one of the two pillars of seasoning.

Acid helps to brighten and elevate existing flavors in food, it provides contrast with other flavors, and it helps to balance overall flavor profiles. When we add acid to foods, we describe the resulting sensation as bright, sour, sharp, or tangy. I like to say that acidity brings a mouthwatering brightness that makes flavors really pop.

Think about the breakdown of a piece of pizza— dough and cheese on its own is starchy, fatty, and rich. These are delicious, but only with the tomato sauce does it become a perfect combination of flavors. The acidity in the sauce provides a tangy contrast to the starchiness and richness of the other ingredients, bringing overall balance to the dish.

Concentrated Sources of Acidity

The most common sources of concentrated acidity, or what I like to call direct acidity, are vinegar and citrus. Both of these elements are highly acidic, and though they also add additional flavor, their main driver is acidity. As I mentioned in the pantry lesson, you should always have a few sources of concentrated acidity on deck for cooking.

• Vinegar

Vinegar is produced by fermenting alcohol, which significantly ups its acidity and its complexity. The flavor of vinegar can vary a lot depending on what base is used. Rice vinegar, red wine vinegar, and apple cider vinegar are all acidic, but they each bring different additional flavors to the table.

A good rule of thumb for pairing vinegars is to think about the alcohol that’s used to make it and where that’s commonly consumed. Rice-based alcohol like sake and soju is common in Asia, so rice vinegar tends to pair well with Asian dishes. Wine is common throughout much of Europe and the Mediterranean, so red wine vinegar, white wine vinegar, champagne vinegar, and sherry vinegar all work well with those cuisines. Malt vinegar (made from beer) and apple cider vinegar (made from cider) tend to work well with Central European and American cuisines. These are by no means hard and fast rules, but they’re helpful heuristics.

In general, I like to keep at least one of each of both lighter vinegars (rice vinegar, champagne vinegar, white wine vinegar) and darker vinegars (red wine vinegar, Balsamic vinegar, Chinese black vinegar) in my pantry. Lighter vinegars are useful for adding just a pop of brightness, while darker vinegars tend to bring more flavor and complexity (umami, sweetness, etc).

• Citrus

The juice of citrus fruits is very acidic and offers one of the best sources of concentrated acidity. Lemons, limes, oranges, grapefruits, and yuzu all work well here. Again, an easy rule of thumb for pairing is to think about the citrus fruits most common in the region of the cuisine you’re cooking— limes for Mexican food, lemons for Mediterranean food, etc.

Other Sources of Acidity

While vinegar and citrus are what we use most commonly to wield the tool of acidity in a direct way, there are countless other foods and ingredients that are highly acidic.

Dairy products (milk, yogurt, buttermilk, many cheeses), tomato products (tomatoes, tomato paste, tomato sauce, salsas, ketchup), fermented foods (sauerkraut, kimchi, fermented vegetables, soy sauce, fish sauce), pickled foods (dill pickles, pickled red onions), alcohols (wine, beer, etc), hot sauce, mustard, and a bunch more all have elements of acidity.

If you’re unsure, try it! Anything that tastes sour or tart has significant acidity and can be used to bring brightness and balance. You can use these ingredients to add elements of acidity to dishes, both by adding them directly to a dish, or by pairing something acidic with another part of a dish (a side of yogurt sauce with roasted chicken, for example).

Use Acidity To “Cut Through” Fat

Chefs often talk about acidity’s ability to “cut through” fat. This is one of the most important concepts in all of cooking, and it’s essential to using acidity properly. Acid balances out all kinds of different flavors, but its effects are most pronounced in terms of its contrast with fat.

When we say that acid “cuts through” fat, what we really mean is that its tartness and brightness contrasts and balances the richness of fatty or oily foods. This is why a classic salad dressing simply includes oil and vinegar— oil on its own would be too rich and fatty, but the acidity in the vinegar helps to balance this. Imagine a really fatty piece of meat— Mexican carnitas or smoked brisket, for example. The simple addition of a squeeze of lime over the carnitas or BBQ sauce over the brisket brings acidity that makes the fatty richness less overwhelming.

Any time that a dish has a lot of richness from fat, you can contrast this with a bit of acidity (and this can come in all kinds of different forms). The end result will be a dish that tastes far more balanced and delicious.

Use Acidity To Brighten Flavors

Sometimes you’ll cook a dish, taste it, and feel that it “just needs something.” In many cases, the answer is a bit of acidity. Think about a simple dish like broccoli roasted with salt and olive oil. The broccoli has earthy vegetal notes, the olive oil brings fat, and the salt provides the first element of seasoning. While great on its own, the dish is really brought into its peak with a squeeze of lemon juice over the top. The acidity from the lemon juice brightens up the entire dish and contrasts the other flavors. This is seasoning in action.

Almost any dish can benefit from a bit of acidity, especially if that’s not already present via other ingredients. Experiment with adding just a bit of acid to dishes, and you’ll quickly get a sense of its transformative power.

Layer Sources of Acid

When it comes to cooking with acid, it functions a lot like salt. If you want a dish to be properly salted, you can’t just add all the salt at the beginning or at the end— it needs time to permeate the dish throughout the cooking process. Acid is similar in that it will taste and function differently depending on when you add it in the cooking process.

Adding acid early in the cooking process will mellow some of its sharpness and allow the flavors to meld more. Adding acid at the end or right before serving will brighten up the dish and add more tartness and tang.

Use Acidity To Balance Other Major Flavors

Acid and salt are the two core elements of seasoning because they help elevate and balance flavors. We use salt to enhance existing flavors in food, and we use acidity to contrast and balance flavors.

Think of some of the major flavors you encounter:

• saltiness (ex: soy sauce)
• umami (ex: anchovies)
• sweetness (ex: honey)
• fattiness (ex: Wagyu beef)
• bitterness (ex: dandelion greens)
• earthiness (ex: mushrooms)
• starchiness (ex: white rice)

In each of these cases, a bit of acidity helps to contrast those flavors and bring more balance to the final dish. These flavors on their own can be one-dimensional or overpowering— when you add in an element of acidity, they taste more balanced. As I mentioned before, this works not just with individual ingredients, but also with the overall composition of a dish. If you’re serving multiple things together, the balance can come from different elements that are paired properly. A rice bowl might include white rice (starchy), grilled meat (fatty, savory, salty), soy sauce (umami), and kimchi (acidic). Eaten together, these provide a really nice balance of flavors.

One of the best ways to understand how acidity works in practice is to look at some iconic dishes that we’re all familiar with. There are countless examples where you can see acidic elements being used to brighten, bring balance, and cut through fat. It’s hard to imagine these dishes without these acidic elements, and seeing the role they play in a familiar context will help you figure out how to leverage acidity in the dishes you cook on your own.

Cheeseburgers

The classic cheeseburger is a great example of a dish where acidic elements are used to contrast and cut through rich, fatty elements.

Here the combination of fatty beef and cheese creates a lot of richness. The acidic brininess of pickles, as well as the tomato-based acidity of ketchup, helps to balance those flavors.

Cochinita Pibil Tacos

The use of acidity to cut through fat and balance flavors is seen in a lot of iconic taco dishes. One of my favorites is cochinita pibil, a Yucatan dish made with slow-cooked suckling pig. The meat is really rich, fatty, and full of umami and earthiness from the marinade and the slow cooking process. This dish is traditionally served with pickled red onions, a squeeze of lime juice, and a habanero salsa, all of which provide acidity to contrast those richer elements.

Chicken Parm

Chicken Parmesan is a classic Italian-American dish, and the use of tomato sauce for acidity functions much like it does with pizza. The breaded, fried chicken cutlet is rich and fatty, as is the melted cheese on top. The tomato sauce provides acidic contrast that cuts through the richness of the other elements.

There are countless other examples of well-known dishes (or well-known combinations of dishes) where acidic elements play an important role in balance. When you go out to eat or cook at home, take note of which ingredients are used to produce this effect, and try them out on your own.

Any time a dish tastes flat, unbalanced, or has one element that’s overpowering, there’s a good chance that lack of acidity is the culprit.

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