The Food Lab: Better Home Cooking Through Science

goals: First, it forces aromatic-compound–laden oils
from deep within individual cells to the surface of the
spice and the interstitial spaces between the cells.
This makes it much easier to extract flavor when the
spice is subsequently ground and incorporated into
your food. Second, toasting also catalyzes a whole
cascade of chemical reactions that produce hundreds
flavorful by-products, greatly increasing the
complexity of the spice.
When toasting preground spices, this latter
reaction will definitely occur, but you’ve also got a
problem: vaporization. The flavorful compounds
inside spices are generally quite volatile—they
desperately want to escape into the air and fly away.
With whole spices, they remain relatively locked
down: they can’t escape very easily from their
cellular prisons. With ground spices, on the other
hand, there’s nothing holding them back. They’ll
very rapidly fly into the air. You may have noticed
that preground spices become far more aromatic as
you toast them. Remember this—if you smell it while
you’re cooking, it will not be in your food when you
serve it.
There are rare exceptions to the toast-before-
grinding rule. Indian and Thai curries, for example,
start with ground or pureed aromatics sautéed in
fat. Because most of the aromatic compounds in
spices are fat-soluble, they end up dissolved in the
fat, flavoring the rest of the dish evenly and easily
when other ingredients are added. But for the vast