A pinch of salt is added to desserts to make sweetness more distinct and to soften the bitterness of ingredients such as cocoa, coffee, and caramel. This amount does not make a dessert taste salty; the salt is not perceived as a separate flavor, but when you taste the same dessert made without salt alongside it, the unsalted version seems flat and one-dimensional. The amount is small, and if the recipe includes salted butter or cheese, no additional salt is added.
Salt’s first job in a dessert is to open up the flavors. A very small amount of salt strengthens the tongue’s perception of sweetness; of two cakes made with the same amount of sugar, the one with a pinch of salt tastes sweeter and fuller. Salt also makes flavors such as vanilla, cinnamon, and butter more noticeable. In a dessert without salt, sweetness stands alone and the food starts to taste bland after 1 to 2 bites. Salt breaks up that one-note quality and brings out the dessert’s other flavors as well.
Salt’s second job is to soften bitterness. Cocoa, dark chocolate, coffee, and dark caramel naturally carry bitter notes. Salt reduces the tongue’s perception of bitterness; when the bitterness recedes, sweetness and aroma stand out. That is why a pinch of salt is especially noticeable in chocolate cake, brownies, and coffee desserts. A small amount of salt added when making caramel also softens the burnt edge of the sugar. Salt’s bitterness-softening effect is not unique to desserts; the same mechanism works in savory dishes, too.
The amount varies by dessert, but it is always small. In cake and cookie dough, salt is 0.5–1% of the flour weight; that is 1.25–2.5 grams per 250 grams of flour. A pinch is the amount picked up between the thumb and two fingers, weighing 0.3–0.5 grams; it is enough for small desserts and sauces. Sift the salt with the flour so it is evenly distributed through the dough. Do not add extra salt to a recipe that uses salted butter, because the butter already adds salt to the dough.
There is a threshold at which salt becomes noticeable in a dessert, and it should not be crossed. Where that threshold falls also depends on the dessert’s temperature; salt is less noticeable in a cold dessert and more noticeable in a warm one. A pinch of salt balances a dessert; a few pinches make it taste salty. Desserts where salt is deliberately prominent, such as salted caramel, are a separate category, and there salt is part of the flavor. In an ordinary cake, cookie, or pudding, the salt should remain imperceptible. If you can taste the dough or cream, salt should not register as a separate flavor, only as brighter sweetness.
Salt also works in fruit desserts. A very small amount added to apple pie filling, fruit compote, or jam brings out the fruit’s flavor and lightens the heaviness of the sugar. This is also one reason white cheese goes well with watermelon. Some desserts have no salt at all: salt is not added to the syrup itself, and salt in plain ice cream is optional. Decide by tasting; if a dessert tastes one-dimensional without salt, a pinch can fill that gap.