Acidulating liquid can impart a sour flavor to fruits, so a pinch of sugar is recommended to reduce the pucker. Since salt also slows browning, a pinch of salt added to soaking vegetables will add flavor and aid against discoloration. Additionally, vegetables (such as green beans) can be cooked in acidulated water which will help them to retain their color instead of graying or browning when they are cooked. This can make cooked vegetables look much more appetizing, and the faint hint of acid will add to the flavor.
Acidulated water also is used in poaching because the lower pH of the water will help the proteins in ingredients such as eggs and fish to cook thoroughly. When poaching eggs, a couple of teaspoons of white vinegar are all you need. Bring the water to a boil, then turn down to simmer. The vinegar water should have tiny bubbles that stick to the bottom of the pan, NOT a rolling boil. Crack your eggs into a bowl, and then slowly tip the eggs from the bowl into the water.
Additionally, fresher eggs will hold a better, rounder shape. The whites in fresher eggs are usually tighter and more congealed. After about three minutes in the water, the eggs will be poached medium. Remove from the acidulated water with a slotted spoon and serve.