Slow cooking allows aromatics to release their flavors gradually and meld together, creating a deeper, more complex flavor profile, while fast cooking extracts flavors quickly, resulting in a brighter, but potentially less nuanced, taste.
The way you cook aromatics significantly impacts the final flavor of your dish. Slow cooking, like in a stew or braise, provides ample time for aromatics such as onions, garlic, and herbs to break down and release their volatile compounds. These compounds interact with each other and other ingredients over a longer period, leading to a richer, more integrated flavor. The Maillard reaction, responsible for browning and savory flavors, also occurs more gradually, contributing to the depth of flavor. Think of a slowly simmered tomato sauce; the flavors deepen and become more complex over time.
Fast cooking, on the other hand, like in a stir-fry or quick sauté, extracts the flavors of aromatics rapidly. This can result in a brighter, fresher taste, but the flavors may not have as much time to meld together. The aromatics retain more of their individual characteristics, and the overall flavor profile might be less complex. For example, quickly sautéing garlic will give you a sharp, pungent garlic flavor, whereas slow-cooking it will result in a sweeter, more mellow garlic flavor. The high heat can also lead to some compounds breaking down too quickly, potentially resulting in a slightly bitter or burnt taste if not carefully monitored.
When slow cooking, add delicate herbs like basil or parsley towards the end of the cooking process to preserve their fresh flavor and aroma, as prolonged heat can diminish their impact.