The science of crispier potatoes, better marinades, and richer chocolate

The Science of pH in Cooking

Every food has a pH: a measure of its acidity or alkalinity on a scale from zero (very acidic) to 14 (very alkaline). Shifting that balance by raising or lowering the pH can change the way ingredients cook, appear, and taste. In addition to having a low pH, acids share common traits, including sourness and the ability to denature proteins. Meanwhile, alkaline solutions are bitter and can accelerate browning, break down starches, and even unfold proteins and their peptide bonds. Knowing the science is one thing—applying it in the kitchen is another. When you learn how to control and alter the pH of your food during cooking, your vegetables can retain their bright color, meats can come out more tender, and baked goods can develop deeper, nuttier flavors.

Cooking with pH is fairly straightforward, and once you get the hang of it, there are numerous ways to incorporate it into everyday cooking. By understanding the science—and experimenting with it in your own kitchen—you’ll have the tools to create consistently delicious meals with more predictable results, making you a more confident, skillful cook.

Use Acids to Season Your Food

On their own, acidic ingredients often have a tangy, sour flavor. In cooking, acid is often used as a flavor enhancer. A spoonful of lemon juice, a splash of vinegar, even a pinch of citric acid can brighten a dish and balance bitterness or saltiness.

Cook With Acidic Ingredients

Acid can also have a transformative effect in cooking, especially when added to a liquid base for boiling or marinating. For example, poaching eggs with a bit of vinegar helps the egg whites firm up neatly. Meanwhile, soaking raw fish in citrus juice denatures and “cooks” their proteins in a process that mimics heating. When acid is used in marinades, such as in a base with yogurt or citrus juice, it helps denature proteins by changing their shape, which can make the surface of meat more tender. (But when acid is used in excess and for too long, the meat can become mushy and unpalatable.)

Cook Your Food in Alkaline Conditions

Alkaline conditions can accelerate the Maillard reaction, a fundamental chemical process that occurs when heat transforms proteins and sugars to create new flavor compounds, producing more roasted, nutty, and complex flavors. For instance, pretzels dipped in an alkaline bath before baking develop a deep, toasty flavor and rich color. “A pretzel’s signature deep, dark hue is directly due to an alkaline bath before baking—otherwise they’d be much more pale and have less of a roasty flavor,” Serious Eats’ editorial director, Daniel, notes.

Creating alkaline conditions for your food can also improve your everyday cooking, since this environment can help break down pectin, the cellular glue that holds vegetables together, softening foods and helping foods with long cook times finish faster. Kenji’s recipe for crispy roast potatoes instructs cooks to add baking soda to the cooking water to raise the pH; these alkaline conditions help break down pectin on the surfaces of the potatoes, creating a starchy slurry that results in an extra-crispy exterior once roasted. Dry-brining shrimp with baking soda and salt ensures they stay snappy and juicy, and blanching green vegetables in baking soda keeps them vibrantly green (though keep in mind that using too much baking soda can make them mushy).

Work With Alkaline-Processed Ingredients

Food manufacturers also rely on alkaline conditions when making certain pantry ingredients. Dutch-style cocoa is treated with an alkaline solution to reduce the cocoa’s natural acidity, resulting in a deep, dark chocolate flavor and color that’s ideal for brownies, chocolate ice cream, and chocolate cake. Alkaline conditions can also make starch granules or proteins easier to break down. Nixtamalization—the process of cooking and soaking corn kernels with slaked lime—softens the kernels and makes them easier to grind into masa for tortillas; this process also improves the bioavailability of niacin, an essential nutrient. Century eggs, ramen noodles, and hominy are other familiar alkaline-processed foods that have deeper flavors and chewier textures than their preprocessed counterparts.

Bake With Alkaline-Processed Ingredients (You Likely Already Do)

Mixing alkaline and acidic ingredients, such as baking soda with buttermilk, vinegar, or yogurt, triggers a chemical reaction that produces carbon dioxide, causing doughs and batters to rise. One of the most common sources of confusion in baking comes down to telling the difference between baking soda and baking powder.

Baking soda is pure sodium bicarbonate, a naturally alkaline compound. In addition to providing volume and lift, its alkalinity can accelerate browning reactions, deepening both the color and flavor of baked goods.

Baking powder, on the other hand, is a blend of sodium bicarbonate, a powdered acid (such as cream of tartar), and a starch to keep it stable. Since acid is already included in baking powder, it doesn’t need an external acidic ingredient to activate—just moisture and heat.

Preserve (and Ferment) Your Foods With Acid

Soaking vegetables in an acidic solution infuses them with zippy, bright, and complex flavors. There are a few ways to achieve this. A quick pickle with punchy flavors comes together after submerging ingredients in vinegar (or lime juice) for a brief period. If you’re willing to wait, a salt brine kickstarts fermentation, allowing lactic acid to develop and deepen over days or weeks. Highly acidic environments also inhibit harmful bacteria growth, helping food last longer.