In the Thick of it

by Mark R. Vogel

Sauces come in a seemingly infinite number of styles. The ingredients, methods, and applications for sauces almost know no bounds.

And while sauces certainly vary in terms of their viscosity, thickening them is an oft-needed necessity. This is due to the fact that many sauces are based on aqueous liquids, e.g., water, stock, broth, wine, etc.

A sauce with greater body will adhere better to the food and thus create a more noteworthy flavor sensation. The procedures for concentrating sauces fall into one of two categories: condensation or addition of a thickening agent.

The simplest and most straightforward method of thickening a sauce is to reduce it over high heat. Unlike any of the ensuing methods to be discussed, this has the added benefit of intensifying the flavor by evaporating the excess water.

This technique is almost always employed whenever wine or liquor is added to a sauce in order to vaporize the alcohol. But alcohol or not, any sauce that can be cooked can be reduced.

How much to reduce a sauce will depend on the specific recipe. Generally speaking, when the sauce has congealed enough that it can coat the back of a spoon without running off, (known as "nappé"), it is completed.

Remember that when a sauce is reduced it will naturally become saltier. Thus, hold off seasoning until it is finished or near done to prevent over seasoning.

The most common thickening agents are starch-based thickeners, namely flour, cornstarch and arrowroot. Less common are potato starch and rice flour.

Starch is simply chains of glucose molecules, a type of sugar produced by plants through the process of photosynthesis.

When added to sauces and heated, the long chains of glucose molecules unwind, bond to the water’s hydrogen molecules, and thus gelatinize the sauce. This would be analogous to tying everyone’s hands together at a cocktail party.

The individuals, (water molecules), would not be as free, (or as “fluid”), to move around the room, since the rope, (starch molecules), are holding them together.

Starches cannot just be directly added to a sauce. Doing so would cause dreadful lumps that will never incorporate into the surrounding liquid.