What’s acidity?

To chefs, acidity is control. When used judiciously, acidity can brighten a heavy or fatty dish, bring attention to subtler flavors in a dish, or add complexity. Acidity can also diminish the perception of sweetness and bitterness or decrease the salt required to balance your dish.

When adding acids to a recipe, it’s helpful to think of acidity as not a flavor but a category of flavors. There are different types of acidity, and each type has its pros and cons. Knowing which type of acidity to reach for (or knowing when to combine types of acidity to make a dish more interesting) will make your dishes more cohesive and thoughtful.

So let’s walk through the types of acidity — what they are, what they’re good for, and where to find them.

CiTRIC Acid

When most people think of acidity, they think of citric acid. That’s because citric acid is the primary acid in citrus fruits such as lemon, lime, grapefruit, orange, and yuzu. In lesser amounts, citric acid is in other fruits and vegetables (like tomatoes), too.

To me, citric acid tastes like early morning sunshine. It’s bright, it’s assertive, and it can stand on its own. It is the most acidic (i.e. it is lowest on the pH scale) of the popular acids.

When to use citric acid

I prefer to use citric acid in dishes that I want to taste fresh. Think salads or white fish preparations. When sautéing vegetables, for example, you might find that your vegetables taste less vibrant after you’ve cooked them; a squeeze of lemon can revive those cooked vegetables — bringing out flavors that are more reminiscent of the vegetable in its raw form.

Citric acid loses much of its characteristic tang with heat. You can use this to your advantage if hoping to subdue citric acid (e.g. cooking oranges with braised duck), or you can choose to add your citrus towards the end of the cooking process.

Where to find citric acid

Believe it or not, the rind or zest of citrus doesn’t contain much citric acid. In fact, the zests of limes and lemons I tested had an almost perfectly neutral pH! So your best bet is citrus juice.

In addition to citrus, you can also buy pure citric acid. This can be useful when you want to incorporate the effects of citric acid without the flavors (particularly the sweetness) that come along with citrus. I often use citric acid powder in the leche de tigre for my ceviche when I want more control of the acid levels. This method enables me to marinate my raw seafood in a liquid like shrimp broth instead of using just citrus juice.

Lactic Acid

Lactic acid is the primary flavor associated with lacto-fermentation. If you’ve tasted pickles, sauerkraut, kimchi, miso, or yoghurt, you’ve tasted lactic acid. Even sourdough bread’s acidity is due in part to lactic acid.

I think of lactic acid like turning up the dimmer in your living room. It’s a softer, rounder glow than citric acid — almost milky. I typically associate lactic acid with a bit of funkiness too, partially because it is usually derived from the fermentation of some other ingredient.

When to use lactic acid

I use lactic acid in dishes that need an uplifting note that is not distracting. Earthy broths or sauces seasoned with lactic acid still feel earthy but nonetheless sip lighter.

I often add brightness to vegetable dishes by seasoning the vegetable with its lacto-fermented self. For example, when making celery root puree, I find that adding lemon (i.e. citric acid) is too noticeable — it doesn’t belong! So I season my celery root puree with fermented celery root instead.

Where to find lactic acid

The best way to find lactic acid is to ferment something! Lacto-fermentation is easy, and it enables you to add subtle funk to your dishes. I also like to preserve lemons in order to mellow out the citrus’s citric acid with some lactic acid.

But you don’t have to rely on fermentation to add lactic acid to your dishes. You can also buy powdered lactic acid and incorporate it as needed. I have a stash of this lactic acid powder that I add to my yeasted pizza dough recipe to simulate a bit of the sourness of sourdough bread.

Acetic Acid

Acetic acid is the acidity you associate with vinegar or kombucha. It’s also found in trace amounts in sourdough bread (alongside lactic acid) and wines (especially natty wine or those described as having “volatile acidity”). Acetic acid is usually produced when alcohol is fermented in the presence of oxygen.

I think of acetic acid like shining a flashlight on the heavier elements of your dish. Thanks in part to its pungent smell, it sticks out a bit, never quite mingling with the other ingredients.

When to use acetic acid

The beauty of acetic acid is the accessibility of vinegar varieties. From rice wine vinegar to balsamic and everything in between, it’s easy to find a vinegar that complements your salad or main course.

More so than other types of acidity, vinegar begs for fats to complement its sourness and tame its smell. Emulsions of vinegar and butter or olive oil serve this purpose well.

Where to find acetic acid

I don’t just buy vinegars. I make them, too. Homemade vinegars (especially those made from fruits and vegetables) can have a thicker mouthfeel and sweeter taste, making them more balanced and almost a sauce on their own. The Noma Guide to Fermentation is an incredible resource for making your own vinegar.

When I’m not planning months ahead with a custom vinegar, I also like to flavor otherwise neutral vinegars (like white wine vinegar). For example, before making mushrooms, I might throw mushroom scraps in with the vinegar I plan to use the next day.

Most often, I opt for an extremely strong vinegar called ättika. From Sweden, ättika vinegar is four times as strong as regular vinegar, so it works well when you want to adjust acidity without imparting other flavors. I have a little spray bottle with ättika vinegar that I use to spritz a dish when I realize that it wasn’t as acidic as I was hoping.

Malic Acid

Malic acid is the acidity in a green apple. It’s also the principle acid found in apricots, blackberries, blueberries, cherries, mirabelle plums, peaches, pears, and quince. A cheap white cooking wine tastes like malic acid to me.

I think of malic acid like sunshine through a stained-glass window. It’s subtler than citric acid in a way that I can only describe as warm.

When to use malic acid

I find that malic acid works well to bring life to meat-centric dishes — particularly pork. It mingles well with sweetness, too, making it great for desserts.

I don’t use malic acid much on its own, but I do try to incorporate it into dishes that are already acidic to add more complexity. A sauce with multiple types of acidity can taste like a whole fruit basket! For example, I often add both white wine and vinegar to butter sauces (i.e. I mix malic acid with acetic acid). Fermenting blackberries, similarly, is a means to add lactic acid to malic-rich berries.

Where to find malic acid

I keep some reduced white wine handy to adjust the malic (and tartaric) acidity in dishes. Otherwise, I keep powdered malic acid on hand to adjust the liquids I use in my ceviche.

Other acids

The four acids I’ve described only scratch the surface. But the other acids don’t have as many culinary uses.

Oxalic acid (found in wood sorrel, chives, and purslane) certainly comes in handy (and is reminiscent of acetic acid), but excessive consumption of oxalic acid can be toxic. Tartaric acid is the predominant flavor in tamarind, and it plays an important role in lowering the pH in wine production. It’s also mixed with baking soda to become baking powder. Meanwhile, ascorbic acid is common too — because it’s vitamin C!

Conclusion

Hope this was helpful. And when life gives you lemons, be sure to think twice about whether that’s the acidity life really needs right now.