In the test kitchen, we talk about balance a lot. For savory dishes, this means having appropriate ratios of fat, salt, and acid. Like salt, acid competes with bitter flavor compounds in foods, reducing our perception of them and brightening other flavors. We often season dishes not just with salt and pepper but also with acid before serving. Sometimes you want to taste the acid, such as when you squeeze lemon over a piece of fish. Other times the effect is more subtle, as acid can balance a dish and tease out other flavors without calling attention to itself: Just a dash of vinegar added at the end of cooking, for instance, brings the flavors in a pot of soup into sharper focus.
All About Acid, Cooking's Most Versatile Ingredient
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Below we'll walk you through what foods fall where on the pH spectrum, how to enhance a dish with acidic ingredients, other ways you can use acidity besides adding flavor to a meal, and more.
What Do pH Numbers Even Mean?
The term pH stands for the "power of hydrogen" which measures the acidity or alkalinity in foods, beverages, and more. The total pH scale ranges from one to 14, with seven considered to be neutral. Anything below seven like wine or club soda is acidic and anything above seven like melons and brussel sprouts are considered alkaline-based. The foods in the list below fall on the acidic end of the pH spectrum.
Acidic Foods' pH Numbers
Here are the pH numbers of common ingredients.
- Vinegar: pH 2
- Lemon: pH 2
- Dill Pickles: pH 3.4
- Honey: pH 3.9
- Wine: pH 4
- Tomato: pH 4
- Buttermilk: pH 4.5
- Yogurt: pH 4.4
- Sour Cream: pH 4.6
- Coffee: pH 4.5
- Parmigiano Reggiano: pH 5
- Cream of Tartar: pH 5
- Molasses: pH 5.5
- Natural Cocoa: pH 5.6
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How to Use Acid to Make Your Food Taste Better
Use A Little Lemon and Vinegar: Cooks around the world turn to these sour, acidic ingredients to enhance their recipes. We love to cook not just with lemon juice but with the fragrant yellow zest, too. There are dozens of types of vinegar, but potent distilled white is the most neutral-tasting.
Add A Splash of White Wine: While red wine is also acidic, it lacks the clean flavor (and color) of its white cousin. We use just a tablespoon or two of acidic dry white wine to brighten up sauces.
Try A Little Acidic Dairy: Buttermilk, yogurt, sour cream, and even Parmesan cheese all bring acid to the table as part of their flavorful charm.
Other Ways To Use Acid (Besides Adding Flavor To A Dish)
1. Tidier Poached Eggs: Poaching eggs in acidulated water (water with vinegar or lemon juice added) makes for neater whites. We use a ratio of 1 tablespoon distilled white vinegar to 6 cups water.
2. Spud Supporter: Cooking cut potatoes in acidulated water helps the potatoes hold their shape as they soften.
3. Buttermilk Substitute: Don't have buttermilk on hand? Add 1 tablespoon of lemon juice to 1 cup of milk and let it sit for 10 minutes to “clabber.” (This works with soy milk, too.)
4. Browning Blocker: Rubbing cut avocados, apples, or pears with lemon or lime juice helps prevent them from turning brown.
How Acids Are Used In Baked Goods
Sodium bicarbonate (baking soda) produces carbon dioxide when activated with acidic liquids such as buttermilk or yogurt; this gas causes batters to rise, and the heat of the oven then sets the risen batter.
Did You Know?
Baking powder is a combination of baking soda and an acid salt (such as cream of tartar), so it needs only moisture to activate and produce carbon dioxide.
How Do Fermented Ingredients Work?
Foods such as sauerkraut, kosher dill pickles, kimchi, and kombucha get their acidic tang from natural fermentation. Over time, natural and healthy bacteria convert sugar in the raw ingredients into lactic acid, which then “pickles” the food. Humans have been preserving food via fermentation for millennia.
Why Does Acid Turn Garlic Blue?
The color change is caused by a reaction between enzymes and sulfur-containing amino acids in the garlic (the same enzymes are responsible for garlic’s flavor). When these enzymes are activated by mild acid, they produce blue and green pigments. The compound responsible for this reaction, isoalliin, is formed when garlic is stored at a cool temperature for several weeks (typically in the winter, when pantries are colder).
TAKEAWAY: Blue garlic may look off-putting, but it’s perfectly safe to consume and tastes just fine. To avoid discoloration, use fresh, young garlic for our recipes that combine garlic with acidic ingredients.
Can You Cook Acidic Ingredients in Cast Iron?
When acidic foods are cooked in cast iron for a prolonged period of time, traces of metal molecules can transfer into the food. Though they can give off an unpleasant metallic taste as well as damage the pan's seasoning—these molecules are not harmful when eaten!
It’s OK to use cast iron when making quick-cooking foods with acidic ingredients, such as a wine pan sauce, but don’t use it when making long-cooking acidic dishes. Also, be sure to remove an acidic dish from the skillet as soon as it finishes cooking and remember to season your skillet after cooking. (Read “Seasoning Cast Iron” to learn how to season cast iron.)
TAKEAWAY: You can cook acidic ingredients in cast iron, but you should use a well-seasoned skillet and season it after cooking. Don’t allow an acidic dish to cook or sit in the skillet for more than 30 minutes.