Cooking tomato puree separately before mixing removes its raw, acidic taste and concentrates its sweetness, resulting in a richer and more balanced flavor in the final dish.
Tomato puree, in its raw state, often has a sharp, acidic flavor that can overpower other ingredients. Cooking it separately allows the heat to break down these acids, mellowing the taste and bringing out the natural sugars in the tomatoes. This process, often referred to as 'blooming' the tomato puree, also helps to evaporate excess water, leading to a thicker consistency and a more intense tomato flavor. When added directly to a dish without pre-cooking, the puree may not have enough time to fully develop its flavor, resulting in a less desirable outcome. The Maillard reaction, a chemical reaction between amino acids and reducing sugars that gives browned food its distinctive flavor, also occurs during this separate cooking process, further enhancing the taste. This is especially important in dishes where tomato flavor is prominent, such as pasta sauces, stews, and soups.
When cooking tomato puree separately, add a pinch of sugar to further enhance its sweetness and balance the acidity, especially if the tomatoes are not at their peak ripeness.