In classic French cuisine, leading or mother sauces are the foundation for the entire classic repertoire of hot sauces. These five sauces (bechamel, veloute, espanole, tomato, and hollandaise) can then be seasoned and garnished to make a wide variety of other sauces known as small or compound sauces. The five mother sauces are primarily known for which liquids and what thickeners are used to make them.
Named for its creator Louis de Bechameil, bechamel sauce traditionally was made by adding heavy cream to a thick veal veloute. Today bechamel sauce is made by adding white roux to scalded milk that has been flavored with salt, pepper, nutmeg and an onion piquet (half onion with a bay leaf attached by a clove). It is most often used for egg, vegetable and gratin dishes. Properly made bechamel should taste smooth and creamy with hints of nutmeg, onion, clove and bay leaf.
Veloute sauce is made by thickening a white (usually chicken or veal) or fish stock with a roux. A properly made veloute should be rich, smooth and have an ivory color with a deep luster. Veloute made with chicken or fish stock should taste like chicken or fish, while veloute made with veal should have a more neutral flavor. Veloute made with chicken or veal can then be made into intermediary sauces like allemande (by adding lemon juice, eggs and cream) or supreme (by adding cream).
Next on our list of mother sauces is the espagnole or brown sauce. This sauce is made from brown stock (mainly beef) that has tomato paste and mirepoix added to it and thickened with a brown roux. Espagnole can then be turned into demi-glace or jue lie as an intermediary sauce. Demi-glace is half brown stock and half brown sauce that has been reduced down by half. Jus lie is just brown sauce that has been thickened with cornstarch or simply been further reduced down.
Classic tomato sauce is made from tomatoes, vegetables, seasonings and white stock that is thickened with a blond or brown roux. The modern version, however, does not include roux. Rather all the ingredients are simmered together then pureed. If further viscosity is needed it is not uncommon to add already prepared tomato paste. Sugar or a gastrique is used to finish the sauce. A gastrique is just a small amount of sugar that has been caramelized then has a bit of vinegar added to it. The texture of tomato sauce is grainier than all other classic sauces but still smooth.
The last but most complicated of the classic mother sauces is hollandaise. Hollandaise is an emulsification of egg yolks with warm butter and a small amount of water, lemon juice or vinegar. The yolks must be whipped vigorously with the liquid while the butter is added slowly over a double boiler. This sauce is very temperature sensitive. Having the eggs or butter too hot or too cold will either curdle the eggs or not allow the emulsion to happen thus breaking the sauce. A properly made sauce is smooth, buttery, pale lemon color and very rich. It should also be frothy and light, not heavy like mayonnaise.
From these five classic sauces, French chefs were able to derive a world of other sauces of which there are too many to even begin to list. All it took was the simple addition of some supplemental ingredients, seasonings or garnishes to completely transform these sauces. While the modern cuisine may no longer rely solely on the mother sauces to create tasty and innovative dishes it is always good to remember the roots of good food.