Dry masala powders lose aroma when overheated because the volatile aromatic compounds within them evaporate or degrade due to the high temperatures. This results in a less potent and less flavorful spice blend.
Masala powders are complex mixtures of ground spices, each containing a unique profile of volatile aromatic compounds. These compounds, often oils and esters, are responsible for the distinctive smells and flavors we associate with each spice. When exposed to excessive heat, these volatile compounds become more energetic and readily evaporate into the air, diminishing the spice's aroma and flavor. Furthermore, some of these compounds are chemically unstable and can break down or degrade at high temperatures, leading to the formation of less desirable or even unpleasant flavors. The extent of aroma loss depends on the temperature, duration of heating, and the specific spices in the blend. More delicate spices, like cardamom or saffron, are particularly susceptible to aroma loss from overheating.
To prevent aroma loss, lightly toast whole spices before grinding them into a powder, as this enhances their flavor without overheating. When using pre-ground masala powders, add them towards the end of the cooking process to minimize their exposure to high heat and preserve their aromatic qualities.