Tartness, like sweetness, saltiness, and spiciness, complements the tastes in food, adding life to recipes that would be much less interesting without it: the tanginess of lemon juice, the acidity of wine or a ripe tomato, the undefined but unmistakable zing of a dash of vinegar in a ragout, balances other tastes. Without this balance, the overall taste experience can be flabby, amorphous, uncontained. Tartness frames other powerful, unruly flavors in a recipe.
Most other tastes push the flavors in a dish forward; tartness feels as if it is pulling flavor. Try sucking on a piece of lemon and then biting into a freshly cooked shrimp sautéed with garlic. After an initial puckering, you feel your mouth filling with flavor, like a tire being pumped up with air. Very often tanginess is the one missing element that completes a recipe, puts a bow on it, and advertises that it is as full-flavored as it is going to get.
Sometimes the effect of tartness is completely in the background; for example, with beans or lentils, a dash of vinegar or lemon brightens up the occasional palate-deadening effect of these healthful foods. Even though tartness stays below the conscious threshold of taste, the chickpeas or white beans or lentils will wake up.
Tartness is so assertive that one tends to forget that it often serves as a mediator. When we add tartness, we can often increase saltiness or sweetness without fear that it will dominate the recipe. The net result is more overall flavor.
With many meats — which are full- flavored but have no acidity— adding a little tartness is crucial in boosting flavor, almost as important as salting. Argentina’s ubiquitous chimichurri sauce, which combines tartness, saltiness, sweetness, and an herbal aroma, is a prime example. It works with any grilled meat, fish, or poultry.
When you use acid as a seasoning, rather than as a dominant flavour — on a slice of roast lamb, a serving of sweetbreads, or a crispy grilled chicken— you effectively double the sensual experience of each mouthful: thus, you are satisfied with less.
In long braises and stews, the acid component of wine keeps the flavor very immediate and focused. Such recipes require acid or they become lackluster, even flabby. Because red wine has bitter tannins as well, it works hand in hand with the acid in the grapes to balance the unctuous rich meatiness of short ribs or boeuf bourguignon. In tomato sauces, white wine is transformational, adding extra tanginess to the sweet, umami, acidic taste of tomato.
Without vinegar or lemon juice, salad dressing would be an uninspiring mix of fat (oil), salt, and pepper. Tartness pulls the fresh taste of a salad together. If not for lemon juice, the sugar in apple pie, or anything based on cooked fruit, would completely dominate. Tartness, with perhaps a pinch of salt, adds just the right amount of counterpoint to a homemade pie’s powerful melody of sweetness.