Flavor Evolution

Once the aroma molecules in herbs and spices are released into a preparation and exposed to other ingredients, the air, and heat, they begin to undergo a host of chemical reactions. Some fraction of the original aroma chemicals becomes altered into a variety of other chemicals, so the initially strong, characteristic notes become more subdued, and the general complexity of the mixture increases. This maturing can be a simple side effect of cooking the flavorings with the other ingredients, but it often constitutes a separate preparation step. When cumin or coriander are toasted on their own, for example, their sugars and amino acids undergo browning reactions and generate savory aroma molecules typical of roasted and toasted foods (pyrazines), thus developing a new layer of flavor that complements the original raw aroma.