A sauce is concentrated flavour, in a liquid or semi-liquid form that complement or enhance the flavour of the main ingredient of a dish. So, a sauce is made of two distinct parts that are the flavour and the consistency. Lets put the complex subject of sauce textures to the side, for the moment, and have a closer look at the vast world of flavours.
Flavour is the combination of two sensations: taste and smell (aroma).
Taste is perceived on the tongue. There are five basic sensations related to taste: saltiness, sourness, savouriness, sweetness and bitterness. These sensations are triggered by water-soluble chemicals, salt, sugars, sour acids, savoury amino-acids and bitter alkaloids. The "hot" pungency and astringent sensations are not true tastes they are classified as a form of pain. But still perceived by our tongue.
Smell is perceived in the upper nasal region and comes in thousands of different aromas. They usually are described by the foods they remind us of. They have been classified in 25 different genres (groups). They are: floral, spicy, citrus, berry, tree fruit, tropical fruit, non-vinifera grapes, dried fruit, artificial fruit, green leafy, green stemy, dried leaves, nutty, phenolic, caramel, burnt, papery, hot, sulfur, yeasty, bacterial, moldy, earthy, oxidized, and contaminated (source Cornel University).
The molecules that we can smell are usually more soluble in fat than in water. That little part of them that aren't embeded in fats are the one that we can smell. Being water-soluble, these molecules can escape more easily into the air where our smell detectors can catch them.
So, when we are making a sauce we have to make sure that the combination of taste and aroma is respected. Neither of the two sensations alone is fully satisfying. But it is not all, recent studies have demonstrated how taste sensations affect our smell sensations. They showed that the sugar in sweet food enhances our perception of aromas. It is also true with salt in savoury foods.
Sauces as carrier of flavours form a broad spectrum. At one end they can be made of a simple mixture that bring a pleasing contrast to the main ingredient itself or add a flavour that is missing. Butter or cream provides richness to mash potatoes, salsas add pungency to fish or chicken. At the other end of the spectrum are complex flavour mixtures that fill your mouth and nose with sensations. These sauces provide a strong environment in which the flavour of the main ingredient blends itself. Amongst those, the "jus" of the classic French tradition. Their complexity comes from the extraction and concentration of savoury amino-acids and other taste molecules as well as the generation of meaty aromas by mean of browning reactions (maillard reaction) between amino-acids and sugar. In the Chinese tradition, braising liquids based on soy sauce get their complexity from the cooking and fermentation of soybeans. In Indian, Thai and Mexican cooking the complex flavours come from spice blends made of a half dozen or more, strongly aromatic and pungent ingredients.
In the light of all what we know, now, about flavour, taste and aromas lets tackle the main problem that all chefs come across: how to improve a sauce. There are two basic principles that can help to analyze and improve a sauce.
- The first one is to look at a sauce as an accompaniment of the main ingredient in the recipe and understand that it is going to be eaten in a much smaller quantity. Therefore a sauce should have a concentrated flavour. Just keep in mind that if a spoonful of your sauce taste too strong, it should be just right on a piece of meat or some pastas. You should also remember that thickening agents can reduce the flavour of your sauce. So, it's important to taste and adjust the flavour of your sauce after thickening.
- The second one is to look at your sauce not as a chef but as a chemist. A satisfying sauce stimulates more or less all of our chemical receptors. You know that feeling: "it doesn't taste quite right, something is missing!" It is probably the problem, it is missing in one or more of the chemicals that activates our sensations. The trick here, is to try to rectify the amount of saltiness, acidity, sweetness, sourness, bitterness or savouriness by little touches keeping in mind the overall balance of the sauce.
It seems easier said than done, don't worry there is nothing that a bit of practice can't overcome. Even top chefs need to practice.