Acidification is the deliberate addition of an acidic substance to food or drink to change its flavor, texture, or chemical properties.
It's used to tenderize meat, since acidity helps break down tough muscle fibers, and it's central to fermented foods such as cheese, yogurt, and sauerkraut, where it produces the characteristic tangy flavor and firm texture. In sauces and dressings, an acid such as vinegar, lemon juice, or wine balances other flavors and, in a vinaigrette, helps emulsify the oil and water-based components into a smooth dressing.
Acidification methods fall into two broad categories: direct addition of an acidic ingredient, such as citrus juice, vinegar, or wine, and fermentation, where bacteria produce acidic byproducts that lower a food's pH over time, as in kimchi or sauerkraut.
The goal, whichever method is used, is to balance acidity against a dish's other flavors and textures rather than let it dominate.