Blending aromatics for gravies releases their flavors more intensely and quickly, creating a smoother, more integrated flavor profile compared to using them whole or roughly chopped. This can lead to a more potent and nuanced gravy.
When you blend aromatics like onions, garlic, celery, and carrots (mirepoix), you break down their cell walls. This releases volatile flavor compounds much faster than if they were simply sautéed in larger pieces. The smaller particle size also allows these flavors to disperse more evenly throughout the gravy. Furthermore, blending creates a smoother texture, preventing large chunks of aromatics from dominating each bite. The result is a gravy where the aromatic flavors are seamlessly woven together, contributing to a more complex and balanced taste. The blending process essentially pre-infuses the gravy base with the essence of the aromatics, leading to a richer and more flavorful final product. The heat from cooking further enhances the release of these flavors, creating a synergistic effect.
Be careful not to over-blend your aromatics, especially garlic. Over-blending can release bitter compounds. A coarse puree is often preferable to a completely smooth paste.