Question: I have a recipe that calls for a medium white sauce. Can you tell me what this is and how to make it?
Answer: In the fourth edition of “Food Fundamentals” (John Wiley & Sons: 1985) author Margaret McWilliams explained that white sauces are starch-thickened sauces that are used widely in cooking. The “ability to prepare a smooth sauce of the appropriate viscosity for the desired end use is key to making such diverse products as souffles and cream soups.
“Basic white sauces and their variations can be prepared successfully if certain basic knowledge has been acquired. One of the key pieces of information is the appropriate viscosity of white sauce for different applications. The four viscosities of white sauces and their suggested uses are:
“Thin sauce: Cream soups.
“Medium sauce: Creamed vegetables, cheese sauce and gravy.
“Thick sauce: Souffles.
“Very thick sauce: Binding agent for croquettes.
“These sauces vary in the proportion of flour and fat they contain in relation to the milk. The fat used may be butter, margarine, shortening or salad oil, depending upon the flavor and color characteristics desired in the finished product.”
To prepare a white sauce, McWilliams said, “First, the starch is blended thoroughly with fat that has been melted or with oil to help separate the starch granules. Then this fat-starch slurry is blended with cold liquid to disperse the starch still more.
“An absolutely smooth product must be achieved before any heat is applied to the starch mixture. Any lumps present prior to heating will remain throughout the preparation . . . resulting in a poor texture and a product that is slightly thinner than desirable.”
Once the sauce is smooth, heat should be added at a moderate rate. Constant stirring throughout the heating period is essential to produce a smooth sauce. Stirring with a wooden spoon helps to maintain a uniform rate of heating.
These are the proportions for the different types of white sauces:
Thin: 1 tablespoon flour, 1 tablespoon fat, 1 cup whole milk, teaspoon salt.
Medium: 2 tablespoons flour, 2 tablespoons fat, 1 cup whole milk, teaspoon salt.
Thick: 3 tablespoons flour, 3 tablespoons fat, 1 cup whole milk, teaspoon salt.
Very thick: cup flour, cup fat, 1 cup whole milk, teaspoon salt.
“A thin sauce should be thickened very slightly, but should have a definitely fluid nature. In contrast to the thin sauce, the medium sauce should flow rather slowly so that a creamed dish will not flow all around a plate quickly. Since a thick sauce needs to be able to be folded into beaten egg whites, it needs to be spreadable, but should flow extremely slowly. Paste-like is a reasonable description of the desired consistency of a very thick sauce; remember, this is the sauce used to hold ingredients together for deep-fat frying.”
Regardless of the viscosity of the sauce, the product should be perfectly smooth. Lumps may result from inadequate mixing of the starch with other ingredients, according to McWilliams. They may also result from too little stirring in all areas of the pan during heating. If a sauce starts to get lumpy during cooking, the heat should be reduced to allow time for the stirring to keep up with the cooking process. Using a heavy pan for preparing a white sauce can be invaluable in helping to eliminate scorching.