The Right Starch

I’d be surprised if any cooks reading this column could claim that they’ve never had gravy turn out lumpy. And who hasn’t struggled with a sauce that refused to come together? It’s not difficult to thicken a liquid with starch, but the two must be combined correctly and heated properly.

Starches are efficient--the small amount needed to thicken something doesn’t even flavor the food. The thickening power of flour, cornstarch, arrowroot and potato flour differs, however, so it’s important to know how much of each to use.

Flour, milled from wheat, is still the starch most frequently used as a thickener in this country. Cake flour contains the most starch, followed by pastry flour, then all-purpose flour. Bread flour shouldn’t be used as a thickener because it contains too much gluten and will make a sauce stringy and gummy.

To eliminate its raw flavor, flour must be cooked at least five minutes. Acidity of ingredients such as wine and tomatoes causes flour to lose thickening power and should be taken into account when determining how much starch to use in a recipe.

Another important point to remember is that liquids must be degreased before the flour is incorporated. Otherwise the result will be a greasy sauce with a muddy texture and flavor.

The flour may be incorporated by three methods. Whichever you choose, cook the mixture in a heavy-bottomed saucepan--not aluminum, which can discolor the sauce.

* Roux--Made with equal amounts of flour and butter. Heat the butter until the foam subsides (Step 1). Add the flour (Step 2), stirring to produce a smooth mixture. Continue to cook over medium-low heat, stirring, two to three minutes for each two tablespoons of butter and flour, until it resembles a honeycomb and is pale, straw-like in color.

Remove the pan from the heat. When the roux has stopped bubbling, add the liquid all at once (Step 3). Whisk quickly and thoroughly to produce a smooth mixture, then return the sauce to the heat and simmer until thickened. As an extra precaution to prevent lumps, heat the liquid before adding it to the roux.

This method produces what is known as a white roux. To prepare a brown roux, the flour is either cooked for 15 to 20 minutes in clarified butter or browned first in the oven, then cooked with butter. Browning the flour reduces its thickening power.

* Beurre manie--Similar to roux, but this uncooked mixture of flour and fat is added near the end of the cooking period. Use 1 1/2 to 2 tablespoons of beurre manie for each cup of liquid to make a medium-thick sauce.

Knead together equal parts of butter and flour (Step 4) to form a thick paste. A pastry scraper works well (Step 5) for this step.

Break off small pieces (Step 6) and whisk into simmering liquid. The pan should be removed from the heat as soon as the sauce is smooth and reaches the desired thickness.

The beurre manie mixture may be stored in the refrigerator, tightly wrapped, for two to three weeks. It’s also excellent for rescuing sauces that have failed to thicken properly.

* Slurry--Place the flour in a jar and add twice as much cold water or other liquid (Step 7). Cover the jar tightly and shake (Step 8) to produce a smooth mixture. Add the slurry to the hot liquid (Step 9), whisking slowly and continuously until the mixture thickens. A wooden spoon may also be used for stirring.

White sauce, made by any of the above methods, is the basis of many sauces and recipes. It can be made to various thicknesses, depending on the intended use. For a thin sauce, such as soups, use 1 tablespoon of butter and 1 tablespoon of flour to 1 cup of liquid. For a medium, general-purpose sauce, use 2 tablespoons of butter and flour to 1 cup of liquid. For a thick sauce, as might be used for a souffle base, use 3 tablespoons of butter and 3 to 4 tablespoons of flour per cup of liquid.

* Purified starches--Cornstarch, arrowroot and potato starch are more efficient than flour for thickening. To prevent lumps, these starches should be combined with cold water before being added to hot liquids.

Cornstarch, a floury meal ground from white corn, has twice the thickening power and requires less cooking than flour. It produces a smooth, shiny, translucent sauce. High temperatures and extended cooking will thin its effect, so the dissolved cornstarch should be added toward the end of the cooking period.

Arrowroot is made from the ground, dried root-stalks of the arrowroot plant. A rounded teaspoon has thickening power equal to one tablespoon of flour. Like cornstarch, arrowroot produces a clear, transparent sauce. Once the dissolved starch is added, the sauce should be cooked until clear with a minimum of stirring. Do not allow the mixture to boil or it will thin. It can, however, withstand extended exposure to heat.

One tablespoon of potato flour is equal to two tablespoons of flour in thickening power. This starch cooks clear quickly and produces a somewhat shiny sauce. Prolonged cooking causes it to thin.

Of course, there are many other methods of thickening foods. Reduction, emulsifying agents, enzymes, purees, gelatin and foods with natural thickening power can be used with particular foods and in certain cooking situations.

TO THE RESCUE

Sometimes, even if you follow the above directions, sauces and gravies don’t turn out right. A failed starch-thickened gravy or sauce can often be rescued by these emergency measures:

* Lumpy--Force through a fine strainer or process in an electric blender. Return to the heat and simmer for four to five minutes.

* Too thick--Bring to a simmer, then thin with the liquid originally used, adding one tablespoon at a time.

* Too thin--Reduce over medium-high heat, stirring constantly, until it reaches the desired consistency or beat in beurre manie , small pieces at a time, until smooth and the desired thickness.