1.3: Sauces and Thickening Agents

Roux

There are four types of roux:

1. White roux is coo ked only briefly and should be removed from the heat as soon as it develops a frothy, bubbly appearance. It is used in white sauces, such as béchamel, or in dishes where little or no color is desired.
2. Blond roux is cooked slightly longer than white roux, and should begin to take on a little color as the flour caramelizes. It is used in ivory colored sauces, such as veloute, or where a richer flavor is desired.
3. Brown roux is cooked until it develops a darker color and a nutty aroma and flavor. Brown roux is used in brown sauces and dishes where a dark co lo r is desi red. It is important to re member that cooking a starch before adding a liquid breaks down the starch granules and prevents gelatinization from occurring. Therefore, because brown roux is cooked longer than white roux, more brown roux is required to thicken a given quantity of liquid.
4. Cajun Dark Roux is roux that is darker than a traditional French brown roux. This color roux is hard to do and the base color of dark gumbos.

Procedures for Preparing Roux

Whether it will be white, blond or brown, the procedure for making a roux is the same:

1. Using a heavy saucepan to prevent scorching, heat the clarified butter or other fat.
2. Add all the flour and stir to form a paste. Although all-purpose flour can be used, it is better to use cake or pastry flour because they contain a higher percentage of starch. Do not use high-gluten flour because of its greatly reduced starch content.
3. Cook the paste over medium heat until the desired color is achieved. Stir the roux often to avoid burning. Burnt roux will not thicken a liquid; it will simply acid dark specks and an undesirable flavor.

The temperature and amount of roux being prepared determine the exact length of cooking time. Gene rally, however, a white roux needs to cook for only a few minutes, long enough to minimize the raw flour taste. Blond roux is cooked longer, until the paste begins to change to a slightly darker color. Brown roux requires a much longer cooking time to develop its characteristic color and aroma. A goo d roux will be stiff, not runny or pourable.

Incorporating Roux into a Liquid

There are two ways to incorporate roux into a liquid without causing lumps:

1. Warm or hot stock can be added to the hot roux while stirring vigorously with a whisk. (Adding cold stock to a hot roux should be avoided as it can cause the mixture to seize up or create too much of a temperature difference that will create steam and/or burning).
2. Room-temperature roux can be added to a hot stock while stirring vigorously with a whisk.
3. When the roux and the liquid are completely incorporated and the sauce begins to boil, it is necessary to cook the sauce for a time to remove any raw flour taste that may remain. Most chefs feel a minimum of 20 minutes is necessary.

When thickening stock with roux, either (a) add cold stock to hot roux, or (b) add cold roux to hot stock.

Guidelines for Using Roux

1. Avoid using aluminum pots. The scraping action of the whisk will turn light sauces gray and will impart a metallic flavor.
2. Use sufficiently heavy pots to prevent sauces from scorching or burning during extended coo king times.
3. Avoid extreme temperatures. Roux should be no colder than room temperature so that the fat is not fully solidified. Extremely hot roux is dangerous and can spatter when combined with a liquid. Stocks should not be ice cold when combined with roux; the roux will become very cold, and the solidified pieces may be very difficult to work out with a whisk.
4. Avoid over thickening. Roux does not begin to thicken a sauce until the sauce is almost at the boiling point; the thickening act ion continues for several minutes while the sauce shimmers. If a sauce is to coo k for a long time, it will also thicken by reduction.

Proportions: Roux to Liquid

Flour	plus	Butter	or	Roux	plus	Liquid	makes	Sauce
6 oz./190 g	plus	6 oz./190 g	or	12 oz./375 g	plus	1 gal./4 lt	makes	light
8 oz./250 g	plus	8 oz./250 g	or	1 lb./500 g	plus	1 gal./4 lt	makes	medium
12 oz./375 g	plus	12 oz./375 g	or	24 oz./750 g	plus	1 gal./4 lt	makes	heavy

Thickening Variables

1. The starch content of a flour determines its thickening power.
2. Cake flour, being lowest in protein and highest in starch, has more thickening power than bread flour, which is high in protein and low in starch.
3. In addition, a dark roux has less thickening power than a lighter one, so more will be needed to thicken an equal amount of liquid.

The above pictures are examples of different roux colors. Photo Credit to flickr.

The most common method for thickening liquids with flour is to prepare a roux; by cooking the flour with an equal weight of butter. This attenuates the flavor of the flour and eliminates lumps. Then, hot liquids are added to the cooked roux, and the mixture is brought to a simmer until it thickens. Because flour contains proteins and other compounds that impart flavor, sauces thickened with roux are usually skimmed for at least 30 minutes once they have been brought to a simmer to eliminate impurities.

Although stock that is used for sauce making should be carefully skimmed and degreased before it is combined with roux, further skimming is necessary once the roux has been added to eliminate the butter and to remove impurities in the flour. One excellent method for using flour is to cut the amount called for in classic sauces by half and then reduce carefully the thickened sauce to the desired thickness. This method allows more time for skimming and degreasing and will attenuate any floury taste.

In classic French cooking, both white and brown roux are prepared. White roux is used for white sauces; brown roux, for espagnole, the traditional base for the classic brown sauces. To prepare brown roux, the flour is either cooked for 15 to 20 minutes in clarified butter or browned first in the oven and cooked with butter in the same way as white roux. Brown roux is seldom used in modern restaurant kitchens.

Top rep are roux, use a whisk to stir together equal weights of butter and flour in a saucepan over medium heat. Bring the liquid to be thickened (such as stock or milk) to a simmer in another pot. Cook the roux for about 5 minutes, until it has a pleasant toasty smell, and then remove the saucepan from the heat fora minute to let the roux cool. Return the pan to the heat and pour in the hot liquid while whisking. Continue whisking until the sauce comes to a simmer. Turn down the heat and slowly simmer the sauce (such as béchamel or veloute) for 30 minutes. Skim any froth and impurities from the sauce's surface with a ladle. (It is also possible to thicken liquids with roux by simply adding the cold liquid to the hot roux thus saving time and a pot. When using this method, however, be careful to whisk thoroughly to prevent lumps.)

Starches

In the first edition of Le Guide Culinaire, published at the turn of the century, Escoffier predicted that the traditional roux-thickened sauces would be replaced with sauces thickened with purer forms of starch such as arrowroot, potato starch, and cornstarch. Using these starches would eliminate the need for the careful skimming necessary to rid flour-thickened sauces of impurities. He was correct in predict in g the demise of flour-thickened sauces but incorrect in assuming that other starches would be used to fill the gap.

Perhaps the glossy look of sauces thickened with these pure forms of starch explains why Western chefs and diners have never grown accustomed to cornstarch- or arrowroot-thickened sauces. The look of these sauces is almost too perfect, like costume jewelry that glitters just a bit too garishly.

Almost any thickener has drawbacks, which can be lessened by using the thickener in tandem with other methods or ingredients. A small amount of starch added to an already well-reduced stock or cooking liquid will hardly be noticed.

One method occasionally used in contemporary kitchens is to prepare a basic brown stock, reducing and degreasing it to concentrate flavor and eliminate impurities, and then thickening the entire stock with arrowroot. This lightly thickened brown sauce base - a kind of arrowroot espagnole - is then used as a base for made-to-order derivative sauces. When preparing a base in this way, starch must be used judiciously: There is nothing more irksome than a deeply colored, glistening sauce with no taste.

Purified starches should be worked to a thin paste with cold water before being added to hot liquids. If added directly, they will form insoluble lumps that must be strained out. Purified starches are approximately twice as efficient as flour is in thickening.

Starches derived from roots and grains are among the oldest and most versatile thickeners for sauces. They are inexpensive and efficient in small amounts, so that they can be used without imparting a flavor of their own.

Starches must be combined with liquid and heated almost to boiling to be effective. Some starches are purer than others. Cornstarch, arrowroot, and potato starch are almost pure starches and produce shiny sauces, whereas flour contains protein, which gives flour-thickened sauces a slightly mat appearance.

Flour

In Western cooking, flour has long been the most popular sauce thickener. Although flour has largely been rep laced in recent years by other thickeners, it is still the appropriate choice for many country-style and regional dishes. Chefs are also learning to use flour in limited amounts in conjunction with other thickeners.

One precaution to take when using flour for sauce making is to always make sure that liquids to be thickened have been thoroughly degreased before the flour is incorporated. Flour binds with fat and holds it in suspension throughout the liquid, making it difficult to skim. The result is a greasy, indigestible sauce with a muddy texture and flavor.

Cornstarch

Cornstarch, a very fine white powder, is a pure starch derived from corn. It is used widely as a thickening agent for hot and cold sauces and is especially popular in Asian cuisines for thickening sauces and soups. Liquid s thickened with cornstarch have a glossy sheen that may or may not be desirable.

One unit of cornstarch thickens about twice as much liquid as an equal unit of flour. Sauces thickened with cornstarch are less stable than those thickened with roux because cornstarch can break clown and lose its thickening power after prolonged heating. Products thickened with cornstarch should not be reheated.

Incorporating Cornstarch

Cornstarch must be mixed with a cool liquid before it is introduced into a hot one. The cool liquid separates the grains of starch and allows them to begin absorbing liquid without lumping. A solution of a starch and a cool liquid is called a slurry. The starch slurry may be added to either a hot or cold liquid. lf added to a hot liquid , it must be stirred continuously during incorporation. Unlike roux, cornstarch begins to thicken almost immediately if the liquid is hot. Sauces thickened with cornstarch must be cooked gently until the raw starch flavor disappears, usually about 5 minutes.

Arrowroot

Arrowroot, derived from the roots of several tropical plants, is similar in texture, appearance and thickening power to cornstarch and is used in exactly the same manner. Arrowroot does not break clown as quickly as cornstarch, and it produces a slightly clearer finished product although it is much more expensive.

Potato Starch

Although potato starch was one of the first starches to be used in French cooking, it has never been popular as a sauce thickener in the United States. It is used in the same way that cornstarch and arrowroot are. Like cornstarch, it tends to break down after prolonged exposure to heat.

Beurre Manie

Beurre manie is a combination of equal amounts, by weight, of flour and soft whole butter. Beurre manie is used for quick thickening at the end of the cooking process. The butter also adds shine and flavor to the sauce as it melts.

Procedure:

1. Knead flour and butter together until smooth.
2. Form the mixture into pea-sized balls, and then whisk the beurre manie gradually into a simmering sauce.

Like roux, beurre manie contains equal parts by weight of butter and flour. It differs from roux, however, in that it is not cooked and is usually added at the end of a sauce’s cooking rather than at the beginning. It is most often used to thicken stews at the end of cooking when the braising liquid is too thin. To prepare beurre manie, simply work together equal parts by weight of flour and butter with the back of a dinner fork until they forma smooth paste. To thicken a liquid simply whisk in the beurre manie a bit at a time, and wait for the liquid to come to a simmer (the thickening effect does not occur and cannot be gauged until the mixture comes to a simmer). Continue in this way until the liquid has the right thickness. Unlike roux, beurre manie should not be cooked any longer once the mixture thickens or the sauce will develop a strong floury taste. One of the peculiarities of flour is that it develops a strong floury taste after 2 minutes of cooking that begins to disappear as the cooking progresses, usually after 30 minutes.

Flouring Ingredients for a Stew

In home-style and country cooking, stew meat is often floured (in French, singer) before it is browned in hot fat. This is an excellent technique because the flour is thoroughly browned, eliminating any starchy flavor; moreover, the browning of the meat is made easier because the flour helps form a crust . The total amount of flour added to the stew is relatively small so that, if necessary, the cook can add more thickener (beurre manie) or reduce the stewing liquid at the end of cooking.

Some cooks add flour to stews by cooking it in the pan along with chopped aromatic vegetables after the meat has been removed. This method is effective as long as the caramelized meat juices on the bottom of the pan are not allowed to burn and too much flour is not used. Be sure to discard any burnt fat and replace it with fresh butter or olive oil before stirring in the flour.

Liaisons

Sauces are distinguished from broths and soups not only because they are thicker but because they are more intensely flavored. Liaisons were used in ancient and medieval cooking as thickeners so that the sauces would cling to the foods they accompanied, making the food easier to eat with the fingers. These liaison-thickened sauces were further developed in the seventeenth century as an economical alternative to earlier sauces, which were essentially concentrated extracts made with enormous quantities of meat. For centuries since, sauces have been thickened not only to help them cling to food but to give them the look of highly concentrated and flavorful meat juices or cooking liquids.

In modern times, chefs and diners have become skeptical of sauces that are thickened only to give them a richer appearance. Today's diner is more impressed by a light-appearing sauce than one that is thick or seems overly rich. Modern sauces are often less thick or have been thickened by reduction alone.

How Liaisons Thicken

Liaisons usually cause thickening by dispersing solids or insoluble liquids in a water-based medium; on a molecular level, these fine components prevent the water from moving freely and thus increase the sauce's viscosity.

Starch thickens sauces because its large molecules (made up of bush-like rows of sugar molecules) unravel in the liquid medium and bond into larger groupings with the water molecules. The efficiency of a particular starch as a thickener depends on the shape and size of its molecules - and how they disperse in the liquid medium.

Whereas the viscosity of starch-thickened sauces is attributable to solids suspended in a liquid (the scientific term for this kind of system is sol), emulsified sauces consist of two mutually insoluble liquids - usually fat and water - suspended one within the other. Emulsions rely on various additional ingredients to prevent the tiny particles from running into one another, joining up into larger particles, and eventually separating into two distinct layers- the usual course of events when combining water and oil alone.

Emulsifiers usually work in one of two ways. In the first, the emulsifier consists of long molecules that float between the microscopic globules of fat (or water, depending on what is suspended in what), preventing the globules from touching one another; the stability of butter sauces containing flour is an example of this. In the second system, the emulsifier molecules are asymmetrical: Half of the molecule is soluble in fat, the other half in water. The result is that half of the molecule embeds itself in the suspended globule while the other half protrudes into the liquid medium. The protruding ends of these molecules prevent the globules from touching and forming larger aggregates. Egg yolks emulsify in this way.

Vegetable and fruit purees can also be used as thickeners and function in different ways dep ending on how they are used. Some vegetable purees contain sufficient starch so that they behave like purified starches such as flour or cornstarch, but, most purees contain insoluble components that give most puree-thickened sauces a relatively rough texture and mat appearance. They also contribute flavor, whereas plain starch does not (at least not an agreeable one). Some purees, such as those made with tomato or green vegetables, contain so little starch that they thicken a sauce simply by adding a large bulk of fine solid particles to a liquid medium. Sauces thickened with these purees alone will separate in to liquid and solid when left to sit unless another liaison is used along with the puree. Vegetable purees are also used as emulsifiers in vinaigrettes, where they prevent the vinegar (or other acid) and the oil from coalescing (joining up into larger globules).

Sauces can be thickened by suspending solids in liquids (such as starch - and vegetable -puree-thickened sauces), liquids in liquids (emulsions, such as hollandaise and mayonnaise), and, in some cases, air in liquids (foams, such as sabayons and hollandaise). A well-made sauce bearnaise is both a foam and an emulsion: Minute fat globule s and microscopic bubbles of air are surrounded by a liquid medium.

Liaison Use

A liaison does not thicken a sauce through gelatinization. A liaison is a mixture of egg yolks and heavy cream; it adds richness and smoothness with minimal thickening. Special care must be taken to prevent the yolks from coagulating when they are added to a hot liquid because this could curdle the sauce.

Procedure for Using a Liaison

1. Whisk together one part egg yolk and three parts whipping cream. Combining the yolk with cream raises the temperature at which the yolk's proteins coagulate, making it easier to incorporate them into a sauce without lumping or curdling.
2. Temper the egg yolk and cream mixture by slowly adding a small amount of the hot liquid while stirring continuously.
3. When enough of the hot liquid has been added to the liaison to warm it thoroughly, begin adding the warmed liaison to the remaining hot liquid. Be sure to stir the mixture carefully to prevent the yolk from overcooking or lumping. Plain egg yolks coagulate at temperatures between 149°F and 158°F (65°C and 70°C). Mixing them with cream raises the temperatures at which they coagulate to approximately 180°F-185°F (82°C- 85°C).
   • Temperatures over 185°F (85°C) will cause the yolks to curdle. Great care must he taken to hold the sauce above 135°F (57°C) for food safety and sanitation reasons, yet below 185°F (85°C) to prevent curdling.

Gelatin

As meats and fish cook, they release juices that contain gelatin, a water-soluble protein. Depending on the cooking method, these juices end up in the roasting pan or the sauté pan, or, in the case of poaching and braising, they are released into the surrounding liquid. When the gelatin is sufficiently concentrated, it gives the cooking liquid a natural, lightly syrupy consistency.

The natural gelatinous consistency that is so appealing in sauces and braising liquids can be achieved in several ways. The most obvious and expensive is to continually reuse meat or fish stocks as moisteners for more meat or fish until the gelatin (and flavor) is so concentrated that the stock has a natural consistency of its own. The resulting liquid is a natural, unthicken demi-glace. Home cooks and professionals have long added strips of pork skin, veal feet, veal knuckles, or chicken or turkey wing tips to stews and stocks to contribute additional natural gelatin.

Restaurant chefs often combine these methods with careful reduction to eliminate liquid and concentrate the natural gelatin. In a restaurant setting, natural gelatin is most often added to sauces at the last minute in the form of meat glace (glace de viande) or fish glace (Glace de Poisson). These glaces not only give a finished sauce the natural texture that results from careful reduction but also provide a complex flavor backdrop to offset more assertive components, such as wine or herbs, which are added to give the sauce its final character.

In the last twenty years, sauces made by natural reduction and concentration of meat and fish flavors have gradually replaced the more traditional flour-thickened sauces. Although these sauces are almost always better than a car e less, / made roux-based sauce, there are disadvantages to relying on reduction alone to give a sauce a syrupy or " sauce like" consistency. If a sauce has been overly reduced, it will feel gluey in the mouth; it will also quickly congeal on hot plates. Stocks and sauces that have been overly reduced often have a flat, cooked taste that must be offset with more assertive flavors. For this reason, natural gelatin alone is rarely relied on to thicken a sauce. Sauces containing a high concentration of natural gelatin are often finished with butter, which attenuates the gelatin's stickiness.

Egg Yolks

Because they thicken sauces in several ways, egg yolks are versatile liaisons. They provide the base for emulsified sauces, such as mayonnaise and hollandaise, and are used in conjunction with cream to finish the cooking liquid of poached meats and fish. They not only form emulsions of fat and liquids but also combine with air so they can be used for sabayon sauces. They are also used to give richness and texture to crème anglaise.

Egg yolks contain several emulsifiers - among them, cholesterol and lecithin, which account for their versatility. Many scientific studies have been done to explain the behavior of egg yolks, but a few tips and precautions are especially useful to the saucier. Sauces containing egg yolks should not be allowed to boil unless they contain flour, which stabilizes them. Sauce allemande and pastry cream are examples of sauces with flour that are boiled after the yolks are added. Egg yolks are also stabilized to some degree by sugar and acids such as lemon and vinegar, but not so much that the yolks can be boiled without curdling.

When combining egg yolks with hot liquids, be sure to whisk some of the hot liquid into the yolks before returning the mixture to the saucepan. If the yolks are added directly to a hot liquid, they are liable to coagulate as soon as they are exposed to the heat. Never cook sauces containing egg yolks in aluminum pots, or the sauces will tum gray.

Egg yolks and cream

Egg yolks are rarely used alone as a thickener for sauces. They are usually combined with cream, and then added to a liquid already lightly thickened with flour. Blanquette de veau, a white veal stew finished with cream and egg yolks, one of the cornerstones of French home cooking, illustrates the use of egg yolks as a final liaison for poached meats. The pieces of veal are poached in water or white veal stock along with aromatic vegetables and a bouquet gami.

When the veal is tender, the liquid is strained, thickened into a classic veloute with flour - about 3 ½-ounces (100 grams) roux to 1-quart (1 liter) poaching liquid - and then finished with the cream and egg yolk liaison . Recipes vary, but an egg yolk liaison is usually made by combining each yolk with 3- to 4-tablespoons (45 to 60 milliliters) heavy cream and then using 3 to 4 egg yolks' worth of this mixture to thicken 1-quart (1 liter) of veloute. After the liaison has been added to the veloute, the sauce is then gently stirred until it naps the back of a spoon. The stability of the egg yolks will depend on the proportion of flour in the veloute, but most recipes do not risk curdling and warn against letting the sauce boil.

Cream

Heavy cream has long been used to finish cooking liquids and sauces, but only in recent years has reduced cream largely replaced roux as a thickener, becoming an almost universal base for white sauces. Because of its richness, chefs are beginning to use cream more judiciously, and many of the reduced cream-thickened sauces of the last two decades are being abandoned for lighter versions, in which only enough cream is used to contribute a smooth texture.

Heavy cream can be used to finish a sauce, to give it a smooth texture and a more subtle flavor, but it becomes effective as a thickener per se only when it is reduced. Heavy cream or crème fraiche can be reduced and used in two ways. They can be reduced alone and used as needed as thickeners for last-minute sauces, or the cream can be combined with the ,sauce base or cooking liquid and the two reduced together. The second method is best used for sauces made in advance. One of the most commonly used methods is to finish pan sauces with cream (see the recipe that follows).

Whichever method is used, several precautions should be followed when reducing cream. Always reduce cream in a saucepan three or four times its volume; if cream is allowed to boil for even a few seconds, it will boil over. Although it is not necessary to stir or whisk simmering cream continually, give the cream a quick whisking at least every 2 minutes while it is reducing. Cream that is allowed to sit unheeded over even a low flame will become granular and may break.

Always use a saucepan with a large enough diameter to accommodate a medium to high flame. If the pan is too small, the flame will wrap around the outside of it and cause the cream to brown along the pan's inside, discoloring the finished sauce. This is less of a problem on an electric range. Never cook cream covered. Water will condense on a lid or covering and drip down into the cream, causing it to become granular and eventually to break.

When using reduced cream as a thickener for wine sauces, be sure to reduce the wine thoroughly before adding the cream. Not only can the raw wine's acidity cause the cream to break, but an unpleasant flavor of uncooked wine will remain in the sauce.

The degree that heavy cream should be reduced can vary, from one-third to two-thirds its original volume, depending on its butterfat content and the desired thickness of the finished sauce. In other words, if 1 ½ cups (375 milliliters) of heavy cream were added to ½ cup (125 milliliters) of flavor base, the mixture could be reduced to ½ cup (125 milliliters) for a very thick sauce or to 1 cup ( 250 milliliters) for a lighter sauce.

When used alone, reduced cream is very rich and sometimes has a slightly chalky texture in the mouth. Thus, it is rarely used as the only thickener for sauces but is usually used in conjunction with butter, egg yolks, or flour. Butter is often used to finish reduced cream sauces to give them an appealing sheen and a smoother texture; it of course does nothing to attenuate the sauce's richness. Some chefs use roux as a preliminary thickener for the sauce base or add beurre manie at the end so that the sauce requires less reduction and is hence less rich (and expensive). Using flour to augment the thickening power of cream is almost the same as preparing a classic sauce supreme, except the approach is reversed.

Double Cream

European recipes often call for double cream or crème double. Double cream has an especially high butterfat content and is particularly useful as a sauce thickener because it requires less reduction. It is not marketed in the United States but can be prepared using homemade crème fraiche. To prepare double cream, line a large strainer with a wet napkin or a triple layer of cheesecloth, fill it with crème fraiche, tie it at the top, and suspend it overnight in the refrigerator. The whey drains from the cream, leaving the remaining cream with a higher butterfat content. The approximate butterfat content of the finished cream can be calculated by measuring the amount of liquid (whey) that drained off the cream (for example, if 1 quart (1 liter) of cream released 2 cups (500 milliliters) of whey-that is, half its volume-then the butterfat content can be doubled, to 70 percent, given that heavy cream is 35 percent butterfat).

Butter

Butter has long been used in classic French cooking to finish sauces thickened with flour and for certain simple pan-deglazed sauces. In recent year, it has become popular as a liaison for flourless sauces and in fact has become the thickener of choice for made-to-order brown sauces.

When you whisk butter is into a hot liquid, it forms an emulsion, similar to the action of egg yolks. The milk solids and proteins contained in the butter act as emulsifiers, which keep microscopic globules of fat in suspension and give butter sauces their characteristic sheen and consistency. Because the milk solids contained in the butter are what maintain the emulsion, sauces and cooking liquids cannot be thickened with clarified butter. In fact, cold butter, itself an emulsion, is preferable to warm butter that may have begun to turn oily. Emulsions based on butter alone are less stable than reduced-cream sauces, egg-yolk sauces, or sauces that contain flour. Until recently, butter was usually used in conjunction with other thickeners. Even today, many emulsified butter sauces are only made to order so they do not sit around and break.

Enriching Sauces with Butter (Monter au Beurre). Finishing sauces with butter has become one of the most important and widely used techniques in contemporary sauce making. The technique consists of swirling chunks of cold butter into a hot flavor base, usually just before serving.

Certain precautions should always be followed when using butter as a thickener. If too large, or too small, a proportion of butter is used for a given amount liquid the sauce will break. The proportion of butter used to thicken a given amount of liquid can vary from about 20 percent butter to almost ten times much butter as flavor base (for example, beurre blanc). If too small a proportion of butter is used, it tends to separate and float to the surface of the sauce unless the sauce is already an emulsion based on cream or egg yolks, or it contains flour. Large proportions of butter are used to finish intensely flavored liquids – beurre blanc is an example - but if too much butter is used, the taste of the flavor base is lost, the sauce takes on a thick, waxy appearance, and it may break.

Most chefs finish made-to-order sauces by eye and can quickly judge the correct amount of butter to add based on the sauce’s look and flavor. Even though many well-reduced flavor bases do not require a liaison because of the natural gelatin they contain. Butter is often added to soften the sauce's flavor and to eliminate the sticky consistency of highly reduced meat and fish sauces. When using butter to finish a flavor base, it is better to risk over reducing the flavor base before adding the butter. A butter sauce can easily be thinned, but thickening a sauce containing butter would require reduction, and boiling a butter- enriched sauce for any length of time will cause it to break and become oily As a general rule, a made-to-order butter sauce should contain about one third butter

In other words, ½ cup (125 grams) of butter should be used to finish 1 cup (250 milliliters) of liquid sauce base. These proportions will vary widely, depending on the thickness of the sauce base, the intensity of its flavor, the water content of the butter, and the desired consistency of the finished sauce. Because of the richness of butter-enriched sauces, many chefs are starting to use butter in combination with vegetable purees. Tomato and mushroom purees work especially well as a preliminary thickener for brown sauces. Much less butter is then required to give subtlety and a brilliant shine to the sauce.

Emulsification

Sauces can also be thickened by the process of emulsification, whereby un-mixable liquids such as oil and water are forced into a uniform, creamy state. Usually an emulsifying agent such as the lecithin found in egg yolks must be present to aid in the process. The action of stirring or whisking a sauce to incorporate the ingredients will produce an emulsion that is permanent, semi-permanent or temporary. A permanent emulsion, such as that formed when making mayonnaise, will last for several clays. A semi-permanent emulsion will last for a few hours. Hollandaise sauce is one example of a semi-permanent emulsion. A temporary emulsion will last very briefly and usually does not contain an emulsifying agent. Rather, vigorous whisking aerates the mixture, causing the temporary suspension of liquids. Such is the case when oil and vinegar are whisked together to make a simple salad dressing.

Sauce Finishing Techniques

Reduction

As sauces cook, moisture is released in the form of steam. As steam escapes, the remaining ingredients concentrate, thickening the sauce and strengthening the flavors. This process, known as reduction, is commonly used to thicken sauces because no starches or other flavor-altering ingredients are needed. Sauces are often finished by allowing them to reduce until the desired consistency is reached.

Straining

Smoothness is important to the success of most sauces. They can be strained through either a china cap lined with several layers of cheesecloth or a fine mesh chinois. As discussed later, often vegetables, herbs, spices and other seasonings are added to a sauce for flavor. Straining removes these ingredients as well as any lumps of roux or thickener remaining in the sauce after the desired flavor and consistency have been reached.

Monter Au Beurre

Monter au beurre is the process of swirling or whisking who le b utter into a sauce to give it shine, flavor and rich ness. Compound or flavored butters, discussed later, can be used in place of whole butter to acid specific flavors. Monter au beurre is widely used to enrich and finish small sauces.

Nappe

Nappe consistency is a French culinary term. It is a term that refers to the consistency of a sauce. Nappe consistency is achieved when the sauce reaches a thickness that allows it to coat the food evenly. It should not be too thick or too thin. How do you know then your sauce has reached the right consistency? Take a spoon, immerse it in the sauce and turn it over with the back of the spoon facing you. Run your index finger down the spoon (see image above). If you end up with a clean line down the middle, your sauce is ready. Some examples of sauces that nappe consistency applies to are: hollandaise, bearnaise and bechamel. Nappe consistency basically ensures that your sauce will have a velvety smooth texture, without any lumps.

The secret to achieving a perfect, silky, nappe consistency lies in two things: constant stirring (always use a metal whisk) and the right temperature. The stirring will prevent the proteins from separating while keeping a silky consistency. The constant temperature will prevent your sauce from thickening and creating “gruel” - for lack a better term.

Sauce Families

Leading or mother sauces are the foundation for the entire classic repertoire of hot sauces. The five leading sauces béchamel, veloute, espagnole (also known as brown), tomato and hollandaise can be seasoned and garnished to create a wide variety of small or compound sauces. These five leading sauces are distinguished principally by the liquids and thickeners used to create them.

Small or compound sauces are grouped into families based on their leading sauce. Some small sauces have a variety of uses; others are traditional accompaniments for specific foods. A small sauce may be named for its ingredients, place of origin or creator. Although there are numerous classic small sauces, we have included only a few of the more popular ones following each of the leading sauce recipes.

Mother Sauce	Liquid	Thickener
Béchamel	Milk	Roux
Veloute Veal veloute Chicken veloute Fish veloute	White Stock Veal stock Chicken stock Fish stock	Roux
Espagnole (brown sauce)	Brown stock	Roux (optional)
Tomato sauce	Tomato	Roux (optional)
Hollandaise	Butter	Egg Yolks