Most Flavorings Resemble Oils
The flavorful material in an herb or spice is
traditionally called its essential oil. The term
reflects an important practical fact: aroma
chemicals are more similar to oils and fats
than they are to water, and are therefore more
soluble in oil than they are in water (p. 797).
This is why cooks make prepared flavor
extracts by infusing herbs and spices in oil,
not water. They do infuse herbs in watery
vinegar and in alcohols, but both alcohol and
vinegar’s acetic acid are small cousins of fat
molecules, and help dissolve more aromatics
than plain water could. The defensive aroma
chemicals can have disruptive effects on a
plant’s own cells as well as on predators, so
plants take care to isolate them from their
inner workings. Herbs and spices stockpile
their aroma chemicals in specialized oil-
storage cells, in glands on the surfaces of
leaves, or in channels that open up between