Every time I put up a recipe that contains a whole lot of butter I always get a few comments along the lines of: fat has so little flavor all by itself, is it really necessary?. The short answer is yes. The long answer is also yes, just with more mumbo jumbo added to it.
It’s true that fat — even butter — doesn’t have all that much flavor in itself. However it’s real utility is as medium for flavor. Allow me to explain. A typical mouthful of food contains quite a wide variety of molecules: carbs, proteins, fats, etc.. Some of those molecules aren’t technically fats, but they fall into the general fat or “lipid” category because they share certain structural similarities to fats.
I’m falling asleep Joe!! Yes, yes I hear you, just bear with me for a minute or two.
Because fat and water don’t get along, particles made up of these fat-like molecules — some of which contain quite a lot of flavor — tend not to dissolve (disperse) in water. And that’s unfortunate because saliva is very watery stuff. So, these fat-like particles just tumble across your tongue, barely registering on your senses. Such a pity, no? So much lost potential.
The good news is that there are substances that these lipid-like particles will dissolve in: other lipids. Add fat to the mix and suddenly all those flavor-giving molecules spread out, bathing your taste buds in flavor. Thus in this context fats are more than mere fats, they are flavor solvents, and they help us to taste things we wouldn’t be able to taste otherwise. A big pat of butter on toast? Helps us taste the fat-soluble molecules in singed bread. The marbling in a steak? Helps us taste the fat-soluble flavors in meat.
There are other substances that dissolve flavor this way. Alcohol, for one. Alcohol liberates flavors that neither fat nor water can. Think of a line cook making a sauce in a pan he’d just used to sear a steak. There’s plenty of intensely-flavored cooked-on gunk (known as fond) sticking to it. To make his sauce he first applies wine, then stock, then finishes it with butter. To the untrained eye he’s simply adding a bunch of yummy rich ingredients to the pan. What he’s really doing is applying a succession of solvents (alcohol, water, fat) all of which disperse different types of flavor compounds and heighten the sensory experience. Pretty. Darn. Cool.
Another upside of that butter: it helps to “bind” or thicken that sauce, which points to another big advantage of fat: its consistency (another factor of its hatred for water). As mentioned, saliva doesn’t dissolve fat very quickly, which means that fat molecules (and the flavor compounds mixed in with them) adhere to the tongue and the surfaces of the mouth, keeping them in contact with the taste buds for a longer period of time. Think of a bite of a creamy Belgian chocolate bar. Its ability to resist being dissolved (and subsequently swallowed) is what allows you to linger over it.
Thanks for the great question, Cici!