Why Is the Broth So Important to My Homemade Soup Recipes?
Broth is important for two main reasons: it has flavor, and it carries flavor.
First, a broth should be tasty. If it is not, the entire soup will be bland, and you won’t get any flavor at all unless you happen to bite into something that has a lot of flavor in it.
Second, it has to be able to absorb flavors from other ingredients, and carry them to the taste buds. To do this, it must have something called a flavor carrier.
A flavor carrier is a substance, generally in liquid form, that can absorb organic molecules. That’s because everything with flavor, with the exception of salt, is made up of organic molecules.
So what liquids will work as a flavor carrier, and still be really tasty? Water simply will not do the trick. Water cannot dissolve organic molecules, which is why oil and water do not mix. Which brings us to our first flavor carrier: oil and fat. Both of these are capable of carrying flavor, and both can be from tasty sources and thus have a lot of flavor themselves. But oil lends itself more to dressings, and certainly would not act as soup broth.
Alcohol is another flavor carrier. Along with oil and fat, alcohol is also an organic molecule, and can therefore mix with other organic molecules. But aside from being toxic in the quantities required for soup making (although who among us hasn’t tried to consume that much), alcohol has a couple of strikes against it. First, it would be simply too hard to eat something with that much alcohol in it. Second, it evaporates too quickly. For this reason, alcohol plays only a bit part in the production of soup.
What this leaves us with is a material called collagen. Collagen is a dissolved material that comes from bones, tendons, and other tissues of animals. And because it comes from these animal sources, it also brings along with it the flavors that reside within the tissues. And boy, can it carry flavor!
Because collagen is not really a liquid, it is not volatile enough to evaporate like alcohol does. And not being an oil or fat it will not be greasy, or fattening or even terribly flammable. It is more jelly-like than liquid when concentrated, but mixed in warm liquid it dissolves nicely. In fact, it is the active ingredient in gelatin, and in a broth it behaves much the same, but in lesser concentration. For that reason it will not solidify as gelatin does (although freshly made stock can have a jelly-like consistency).
Stock is made very simply by slowly simmering, not boiling, several pounds of raw bones (generally beef, chicken or veal) along with some aromatic vegetables to slowly release the collagen from the bones. By slowly heating it, the collagen has time to dissolve before it gets hardened and stays stuck in the bones. It brings out the flavor from the bones, and picks up the flavors of the aromatic vegetables. This is the essence of a tasty soup broth!
Strictly speaking, a vegetable broth is just that – a broth, not a stock. While it can have a lot of flavor, it will not contain any collagen, so it will not be an effective flavor carrier. That does not mean you can’t make a tasty soup with it, but it does mean you’ll have to find another way to get the flavors to mix better. That is, unless someone has found a source of collagen that does not come from animals, or some replacement for collagen itself.
So that explains clear broths, but what about the creamy broths? Usually they also contain a stock for flavor, but a cream-based soup has one other facet to it. The heavier consistency of the broth lets it stick to the tongue longer. This increases the sensation of flavor, as the taste buds have longer to taste it.
Some cream broths simply have cream or other dairy added to it to make the broth thicker, but most cream soups actually havea white sauce added as a thickener. A white sauce is a butter and flour mixture with milk slowly added to it. Both the flour and the milk help thicken the soup, giving it that creamy texture.
Starch-based broths use the starch of one of the main ingredients rather than flour to thicken the soup. A good example of this is split pea soup. By pureeing the peas, the starch is released and starts to thicken the broth immediately. With a starch soup you can decide whether or not to add dairy depending on taste and desired consistency.
That’s really all there is to broths. Start with a good stock or broth from the store, or make your own at home (I will be posting a recipe soon!), and you will have a soup that tastes like it came from a restaurant, and much better than if it came from a can!
Tips and Techniques
If you find that the broth of your soup is bland, and you don’t want to add salt, try adding some tomato juice, or even just some diced tomato. This works in soups with clear broth, and is very effective in vegetarian soups that don’t get the flavor benefit of a meat stock.