What effect does acid have on green vegetables when they are overcooked?

When green vegetables are overcooked, the effect of acid typically leads to discoloration. This is primarily due to the breakdown of chlorophyll, the pigment responsible for the green color. Overcooking, especially in the presence of acid (such as vinegar or lemon juice), can cause chlorophyll to transform into pheophytin, resulting in a dull, olive-brown color rather than the bright green that is characteristic of fresh vegetables. This change in color is often viewed as a negative outcome, as it indicates that the vegetables may have lost some of their visual appeal and likely some texture and flavor as well.

Enhancing flavor or thickening texture is not a common outcome of overcooking green vegetables in acidic conditions. Instead, flavors can become muted and the texture may turn mushy. Similarly, nutrient retention typically decreases with overcooking, as prolonged heat can destroy heat-sensitive vitamins and minerals found in green vegetables.