Hello, Feast-ga!
For anyone who loves to cook, sauces are a source of endless
fascination. There are few other places in the kitchen where the
gradations from "competent" to "exceptional" show themselves as
clearly as in saucemaking. In the classical French kitchen brigade,
as established by Escoffier, the saucier enjoyed status second only to
the chef himself (no need to be politically correct, here, it was
almost invariably "he"). I am saucier myself, at my fulltime job,
although my circumstances are considerably less exalted than those of
my counterpart in Escoffier's kitchen.
For the purposes of our discussion today, I will follow my own sense
of coherence, rather than an external logic of ordering examples by
course or by technique or ingredient. You strike me as being a
knowledgable person (culinary student, maybe?) so you may feel that
I'm occasionally talking below your level of understanding. This is
for the benefit of other readers who may not have a grounding in the
world of food service.
Before we begin our discussion of sauces, though, there is one
essential preliminary which I would like to address; settling on a
working definition of a "sauce." Wayne Gisslen's "Professional
Cooking," a standard text in many culinary programs, defines a sauce
as
"...a flavourful liquid, usually thickened, that is used to season,
flavour, and enhance other foods."
The text goes on to note that sauces add moisture, flavour, richness,
interest, and visual appeal to the dish.
Harold S McGee, in his seminal "On Food and Cooking," touches on most
of the same points in a more eloquent fashion at the beginning of his
corresponding chapter:
"Sauces are liquids that accompany the primary ingredient in a dish.
Their purpose is to enhance the flavour of that ingredient - a portion
of meat of fish or grain or vegetable - either by deepening and
broadening its own intrinsic flavour, or by providing a contrast or
complement to it. While the meat or grain or vegetable is always more
or less itself, a sauce can be anything the cook wants it to be, and
makes the dish a richer, more various, more satisfying composition.
Sauces help the cook feed our perpetual hunger for stimulating
sensations, for the pleasures of taste and smell, touch, and sight.
Sauces are distillations of desire."
It requires no great intuitive leap to guess which of these statements
comes from a textbook and which from a bestseller, does it?
In sum, then, sauces may be anything from your granny's gravy to the
condiments in our refrigerator doors or the ubiquitous bottle of soy
at the neighbourhood Chinese place. For the purposes of our
discussion, though, we will focus on the various sauces and techniques
which are encountered primarily in restaurants.
Some sauces are very simple, by design. "Red-eye gravy," a Southern
favourite, is a great example. Fry your ham steak in a pan; then when
it's done remove it and pour in some strong coffee. Stir the pan to
get up all the crusty, tasty bits from the bottom, and there's your
sauce.
Now this is a very rudimentary sauce, by any stretch, but it does
answer to the basic definition. In fact, it utilizes a classic
technique which lies at the heart of haute cuisine. Adding a liquid
to the hot pan ("deglazing") as a way to lift up and utilize the
crusty, flavourful bits stuck to the pan's bottom (the "fond," in
French culinary terminology) is every bit as useful for foie gras as
for our ham steak. Sauces created from the main ingredient's cooking
juices are generally termed "a la minute" in the professional kitchen,
meaning that they are completed to order rather than being prepared in
advance and held for service.
If we stopped at this stage, however, we would not necessarily have a
sauce of much finesse. It can (and very often will) have a suitably
concentrated flavour, but you'll note in our definition that adding
flavour is only the beginning of a sauce's duties. Therefore, most
sauces - even those finished a la minute - require a bit more work.
Generally there will be additional enhancements made to the sauce, by
way of various seasonings and flavourings, and it will almost always
be thickened or stabilized in one way or another.
Why is thickening a near-universal stage in saucemaking? Well, let us
reconsider the role of a sauce, as outlined above. A thickened sauce
will cling to a foodstuff where a thin sauce runs off; therefore a
thicker sauce is (counterintuitively) more effective at moistening the
food. A thickened sauce will pool attractively around the food, while
a thin sauce runs across the plate and slops onto the rim; therefore a
thicker sauce is more visually appealing. A thin sauce will have a
sharper, more immediate flavour; a thicker sauce will release its
flavours more slowly onto the palate (either of these effects may be
desirable, depending on the dish). Sauces are intended to add
richness and mouthfeel to a dish; and thickened sauces do this more
effectively than thin sauces.
In short, it is generally thought desirable to bring a sauce, by one
technique or another, to the stage at which it will enrobe the food
(this stage is referred to in French as "nappe") without being gummy
or sticky.
Before we proceed to elaborate on this process, it is well to stop
here and lay one additional piece of groundwork. We have already
decided what a sauce is, in the semantic sense. Now let us define
what a sauce is, in the physical sense.
Sauces consist of a variety of dissimilar substances, caught up
together in combinations of greater or lesser durability. What we
wish to accomplish is to turn such a combination into a stable
emulsion. An emulsion is, simply, a mixture of two or more substances
which would not normally combine. Consider oil and water, a very easy
example. They do not mix. Shake them vigourously and the oil will
break into small droplets, spreading throughout the water, but if you
let the combination sit it will disperse back into the two original
substances. Likewise, if you let the red-eye gravy sit in a glass,
you will see solids settle to the bottom, fat rise to the top, and the
liquids sit between them.
In an emulsion, we have the substance which is mixed in (the
"dispersed phase") and the substance which it is mixed into (the
"continuous phase"). For our purposes, the important detail is that
droplets of the liquid and droplets of the fat will, by their nature,
seek to rejoin and separate from the opposing substance. Our goal is
to stop this from hapening, by one or another technique. Note that I
am deliberately oversimplifying, here, since a real-life sauce seldom
contains only two substances.
This is by way of groundwork, and I won't be making much use of this
terminology; but it is useful to keep in mind what is going on "under
the hood" when we make sauces.
So, let us return to the simple example above - a hot pan deglazed by
a suitably-flavoured liquid - and begin our survey of ingredients and
techniques.
Reduction
=========
The simplest means of stabilizing or thickening a sauce is by letting
it reduce. The cooking liquids which come from any meat or vegetable
are mostly water, with various flavour compounds dispersed among the
water molecules. Simply evaporating some of the water (the continuous
phase) allows a greater concentration of flavour compounds (the
dispersed phase), simply because they will be less dispersed. This
also results in a thicker liquid, for the simple and intuitively
correct reason that it is less "watery."
This method requires nothing in the line of extra ingredients, and
could not be simpler to achieve. Just bring the sauce to a boil, and
wait. The resultant flavours should be clear, concentrated, and
insistent; making reduction a widely useful technique. There is some
potential downside, though. If reductions are seasoned too liberally
at the beginning of the process, some components (salt is particularly
troublesome) may become unhappily dominant. There is also a hazard in
over-reduction. Sauces which suffer from this fault often become
thick and gummy, which is easily remedied by adding more liquid; but
they also may gain a stale "cooked" flavour which cannot be so easily
concealed. Finally, in some cases, it is desirable to retain a clean
fresh flavour which long reduction/cooking would destroy.
While not universally, helpful, then, reduction is a powerful and
simple technique with wide applicability.
Emulsifications
===============
Although almost all sauces are, at some level, emulsifications, we may
also thicken them by deliberately changing the degree or kind of
emulsion. Let's begin this discussion by extending our basic pan
sauce a step further.
Butter: "Monter au beurre"
__________________________
One of the commonest instructions in French cookery is to "monter au
beurre," or "mount with butter." This is a simple enough process.
Having deglazed the pan and/or reduced it, as above, we simply add a
chunk or two of butter to the pan. As we whisk or swirl the pan, the
butter breaks down into droplets of fat which disperse throughout our
sauce. As the butter and liquids become more intimate with each
other, the sauce gains visibly in body and thickness.
In their collaborative book, "A Return to Cooking," the obviously
fascinated writer Michael Ruhlman describes chef Eric Ripert making a
sauce with just this method. Ripert added the butter in small chunks,
tossing the sauce in the pan as if it were a handful of vegetables.
He explained that he was listening for it to have the right sound. As
Ruhlman watched and marvelled, this simple sauce began to make a
distinctive wet "slap slap" noise in the pan, at which point Ripert
pronounced it ready.
It is important to note that this type of sauce is only a temporary
emulsion, designed to be made and served immediately. If permitted to
sit, the butter and pan juices will separate after only a few minutes.
Another example of this type is a basic vinaigrette, which needs to
be shaken up before use. Sauces like these are not suitable for
holding, and therefore may be self-limiting in the professional
kitchen. Not everyone has the luxury of making sauces individually to
order, a clear downside in a busy kitchen. In my next example, I'll
discuss a couple of ways in which temporary emulsions may be made to
last through an evening's usage.
Butter, then, is a useful but limited thickening agent. It not only
thickens but provides richness, flavour, sheen, and an imcomparable
mouthfeel. Although one of the costlier ingredients we will discuss,
it is relatively inexpensive and widely available, meaning that it is
found in almost all professional kitchens. On the downside, the
sauces it produces are only stable in the short term. Butter's star
has also faded in recent years because of health-related concerns.
Cream
_____
The classic French repertoire features a pair of wine and butter
sauces, known as "beurre blanc" and "beurre rouge" (made with,
respectively, white and red wine). These are very similar to the
above example. They are made by reducing the wine with various
flavourings, then whisking in butter to created a thick and creamy
sauce. Like other temporary emulsions, these sauces are prone to
"breaking" (ie, separating back into wine and butter). Unlike the
above sauce, though, it is common practice to make a batch of beurre
blanc (for example) to serve all evening with a fish course.
Now a classic beurre blanc will not usually last through three hours'
service without breaking, although careful attention to temperature
will help. It can be re-emulsified periodically by whisking
(lightweight immersion blenders are your friend, here) but that
becomes a bit of a distraction during a busy service period.
Cream is frequently employed to prolong the usable life of this type
of suspension. Cream reduced by half or three-quarters makes a very
thick liquid, almost like a starch-thickened sauce (which we'll get to
eventually). When added to a butter emulsion, the extra fat globules
of the cream help round out the emulsion and keep it stable longer.
One of the opening chapters of chef Tony Bourdain's crime novel "Bone
in the Throat" has cooks standing outside their restaurant arguing
this very practice. While cream is not a canonical part of beurre
blanc, it is a widely used "cheat," and given that butter and cream
are essentially identical there is little practical objection to using
it this way.
Because reduced cream is resistant to curdling it can be combined with
acidic ingredients (like, oh, wine for example) with relative
immunity. At my part-time job, a fine-dining restaurant, we
frequently use reduced cream (without going through the butter stage
first) to make sauces.
Like butter, cream is one of the costlier ingredients we will discuss,
but still relatively cheap and widely available. Like butter, it adds
much richness and mouthfeel to sauces. On the downside, like butter,
it still only yields a fairly short-lived sauce, and is the object of
health concerns.
Liaisons, and egg-thickened sauces
__________________________________
A further step towards stability may be made by using a "liaison"
rather than plain cream. A liaison is a mixture of egg yolks beaten
into cream; the hot sauce is then whisked carefully into the mixture
until incorporated. When heat is re-applied to the sauce, the
proteins in the egg yolks begin to bind up and immobilize the fat
globules in the butter/cream, making the sauce sturdier. Egg yolks
also contain other emulsifiers such as lecithin, which have a similar
effect.
Eggs are frequently used to thicken fat-based or dairy-based sauces.
Fat-based sauces might include mayonnaise and its variations; or hot
sauces such as the always-popular hollandaise and bearnaise.
Dairy-based sauces include a number of variations on bechamel (see
below), as well as any number of the custard-type sauces (ie, "creme
Anglaise") most often used for desserts.
Eggs, when purchased in commercial quantities, are extremely
inexpensive and are therefore a popular ingredient. A
liaison-thickened sauce has an even richer and silkier mouthfeel than
a butter or cream sauce; unfortunately it doubles the associated
health concerns. Egg-thickened sauces create a further complication
for the cook, as these sauces provide a marvelously nourishing
environment for food-borne bacteria. These potential pathogens are
held in check at temperatures above 140F, but unfortunately eggs
coagulate at about 160F, resulting in a failed ("broken") sauce. That
relatively narrow twenty-degree "window" leaves much to be desired,
given that steam wells and suchlike devices are seldom calibrated with
any degree of accuracy. This means it is difficult for a chef to
avoid the risk of food poisoning, on the one hand, or an unusable
sauce on the other.
Restaurants deal with this in one of three ways. The simplest is to
not use egg-thickened sauces at all. A second approach, common in
lower-end restaurants, is to use pre-made pseudo sauces, in which a
powder is whipped up with one or another liquid to approximate the
flavour of the genuine article. The third, used in better
restaurants, is to make the sauce in small batches which are discarded
after a preset time; and to monitor temperatures closely. In this
latter case, an additional level of safety may be gained by using
pasteurized eggs; which at least (when stored correctly) do not
*introduce* any significant quantity of pathogens to the sauce.
Cold sauces: eggs as emulsifiers
________________________________
While the proteins in egg yolks work effectively as emulsifiers in hot
sauces, they are also notably effective in cold sauces. This is
because, like butter and cream, egg yolks are themselves emulsions of
various substances. When agitated physically, in the presence of a
modest quantity of salt, the granules of egg yolk break down into low-
and high-density lipoproteins (the same LDL's and HDL's of cholesterol
counting notoriety), which are tremendously effective in preventing
fat globules from leaving an emulsion.
The classic egg-thickened cold sauce is mayonnaise, a mixture of egg
yolks and other water-based ingredients (vinegar, lemon juice, or
plain old cold water) with a quantity of vegetable oil whisked in to
make the emulsion.
The ups and downs of eggs in cold sauces are more or less as they
would be in a hot sauce. Temperature is less of a concern, as cold
sauces are typically held under refrigeration, where bacterial grown
is inhibited. Also, the acidic ingredients (and olive oil, if used)
provide antibacterial assistance. Even so, scratch-made mayonnaise
and its variations should be treated as a highly perishable item.
Other emulsifiers
_________________
A few other emulsifiers find their way regularly into our food, but
they typically arrive by way of commercially-prepared product, rather
than being made in the restaurant kitchen. These form part of the
polysyllabic fine print on the ingredients list of your tin or
package; and they may be classed into two types. One type, like the
lecithin in egg yolks, consists of a molecule which is attracted to
fats at one end and water at the other. These bind the two phases of
the emulsion like a policeman to a shackled suspect. The other type
are proteins, longer molecules with several areas of water-affinity
and oil-affinity; the proteins in egg yolks and the caseins in dairy
products are the best of these. Little wonder, then, that egg yolks
are so potent, given that they contain both types of emulsifiers!
The only other emulsifying agent that is widely used in the
professional kitchen is mustard. Mustard stabilizes a sauce much the
same way that starches do, by intervening between droplets which are
trying to cohere together and separate from the emulsion.
Additionally, mustard seeds release a gentle gum, or gelling agent,
when wetted.
Prepared mustards are also used as emulsifiers, to good effect. Not
only do they have the same properties as the freshly-ground seeds,
they also themselves are generally manufactured with emulsifying
agents to stabilize them, hence the prevalance of mustard as an
ingredient in mayonnnaise.
Mustard, whether dry or prepared, is readily available to the
commercial kitchen and is inexpensive. It makes a long-lasting,
stable emulsion, which is a good thing. It also, however, has a
potent and pungent flavour which is not always desirable in the end
product. It is, therefore, a popular and useful ingredient, though of
limited versatility.
This, then, leads us to...
Starches
========
Starches are certainly the most widely-used thickeners and stabilizers
in the culinary world. There are any number of them available to the
cook, although only a relatively small handful are in widespread use.
All of them have distinctive combinations of advantages and
disadvantages.
As discussed briefly above, starches work by interfering in the
emulsion. Ordinarily, the fat and the water phases of an emulsion are
always in flux. Like seeks like, in emulsions as elsewhere, and both
the water and the fat molecules will bind to each other if left to
their own devices. In the presence of starches, however, these
molecules tend to encounter the larger starch molecules rather than
each other.
Starches may be introduced into a sauce at many stages, but (broadly
speaking) in one of only two ways. Starch may be combined into a fat,
either cooked or uncooked; or it may be dissolved in a liquid and then
added. In either case, the preparatory technique is designed to allow
the starch to disperse evenly throughout the sauce before
gelatinizing. As many a novice cook has learned, adding starch to a
hot liquid directly is guaranteed to produce a bountiful harvest of
thick, sticky lumps.
Having said that, let's take a look at the most widely-used starches
and how they differ.
Flour
_____
Most of us, in North America at any rate, grew up on flour-thickened
gravies. Wheat flour has been arguably the single most widely-used
thickener in western cuisine over the last few centuries, and it has
been the backbone of many classic sauces.
To simplify, flour consists of two primary components: starches and
proteins. For the most part, it is the starches which concern us
here. The proteins will generally rise to the top of a sauce as it
cooks and form a skin, which will need to be skimmed off before
serving.
At home, flour is generally added by being mixed into a liquid. Flour
may be whisked into cold water to form a thin batter ("whitewash"),
which for example might then be added to a panful of drippings from a
roast in order to make gravy. Another approach to this, commonly used
in stew (essentially a self-saucing meat dish) is to toss or dredge
the pieces of meat in flour before cooking. In this instance the
surface moisture of the meat itself moistens the flour. When the pan
is deglazed, the starch molecules of the flour are well-browned on the
pan and the surface of the meat, and will thicken up the sauce quite
acceptably.
In the commercial kitchen, two different techniques are more common.
Both employ fat as the "anti-clumping" ingredient. The first, and
best known, is roux. To make a roux, the flour is added to a pan of
fat (usually, but not always, butter) and cooked out while stirring
vigorously. The fat coats the starch molecules, preventing them from
clumping when they encounter the hot liquid. If cooked long enough,
the roux will reach a high enough temperature for the starches to
coagulate; which in turn will shorten the time required for thickening
and finishing the sauce.
Hot liquid may be added to a cold roux, or cold liquid may be added to
a hot roux; either way the sauce will be whisked vigorously to
disperse the roux throughout the body of the sauce. After that it
will be left to simmer until it arrives at the proper velvety texture,
and until the skin of proteins has been thrown to the surface and
skimmed off. Until the starches have fully gelatinized, the sauce
will taste noticeably "starchy" or "floury," a clearly undesirable
trait.
A second option is a technique known as "beurre manie," or kneaded
butter. Essentially it is an uncooked roux: butter and flour are
kneaded together without heating, and stored until needed. Beurre
manie is added at the end of the saucemaking process in order to
achieve the desired consistency. As with roux, the sauce must be
simmered until the starches are fully cooked and the protein has risen
to the surface and been removed.
Wheat flour is as cheap and widespread an ingredient as can be
conceived, and is found in almost all commercial kitchens. Sauces
thickened and stabilized with flour can be held and reheated for days,
as long as proper care is taken with refrigeration and standard food
safety practices. As with most starch-thickened sauces, they will
"set" to a thicker consistency when cold, and loosen back to a thinner
consistency when reheated. They may require some thinning with extra
liquid. Sauces thickened with starches should be reheated carefully,
as they will lose some thickening ability if reheated to a full boil.
Flour-thickened sauces have an agreeably smooth mouthfeel, which is a
good thing. On the downside, flour makes sauces opaque, which is not
always desirable. Also, the relatively long cooking-out time can be a
limitation in a busy kitchen. Finally, the distinctively substantial
nature of flour-thickened starches has fallen into disfavour in
today's top restaurants. Overall, though, flour is one of the most
versatile and cost-effective options at a cook's disposal.
Rice starch
___________
Rice starch has very fine particles indeed, the smallest of starches
in fact, and gives a very silky mouthfeel. It is little seen or used
in Western cooking. Finished sauces made with rice starch are similar
to flour-based sauces, in that they are rather opaque and rather
substantial, in comparison to sauces thickened with other starches.
Rice starch is seldom seen in the North American commercial kitchen,
and is correspondingly hard to find and higher in price. It may be
located in cities with larger Asian communities.
Cornstarch
__________
Cornstarch, in North America at least, is second only to flour in
culinary usage. While culinary traditionalists still adhere to the
use of roux, Escoffier himself looked forward confidently to the day
when purer starches like cornstarch and arrowroot would supplant flour
in the kitchen. Even he had limited patience for cooking out a roux!
Cornstarch does not have the admixture of protein molecules that we've
seen in flour. A pure starch, it is generally added to a sauce by
being whisked into a cold liquid (ie, a "slurry). The slurry is then
whisked into the hot liquid. The result is an almost-immediate
thickening effect, requiring only (and this is important) that the
liquid come to a boil.
Sauces thickened with cornstarch may attain to a truly beautiful
clarity and transluscence, an especially popular characteristic in
Asian cooking. The downside is that cornstarch-based sauces may have
a less-pleasant mouthfeel, becoming downright gummy if overthickened.
Cornstarch sauces are best if served fairly soon, as prolonged heating
makes the thickening break down. Another potential issue with
cornstarch is the need to come to a boil, which makes it unsuitable
for applications in which eggs are used (the eggs will curdle), or
sauces in which the cook wishes to preserve the flavour of the fresh,
raw ingredient.
One specific requirement which is problematic with cornstarch is
freezing. A cornstarch-thickened sauce which is frozen and thawed
will tend to "weep" liquid, a profound shortcoming in this
application. To meet that requirement, manufacturers have developed
"modified" cornstarch (also referred to as "waxy maize") which is not
subject to that failing.
Cornstarch is cheap, widely available, and widely used. Cornstarch
sauces, unless frozen or overheated, hold beautifully for days.
Arrowroot
_________
Arrowroot is derived from a Caribbean plant, Maranta arundinacea. Its
characteristics are similar to those of cornstarch, including the need
for high temperature (bad) and the beatiful clarity of the resulting
sauces (good). Arrowroot gives a more pleasant mouthfeel than
cornstarch.
Although widely used in Latin America and Europe, arrowroot is less
common (and therefore more expensive) in North America. Sauces
thickened with arrowroot are very stable.
Potato Starch
_____________
Potato starch was the first of the refined starches to become widely
available, and it is still important in Europe despite its
limitations. The particles of starch are, themselves, larger than any
of the other widely-used thickeners, which means that the finished
sauces tend to have a slightly grainy character. Potato starch
thickens quickly, and then will loosen somewhat under prolonged
cooking. Unlike most other starches, potato starch will resist
congealing as it cools, resulting in sauces which are more pourable
when refrigerated. This in turn means that they reheat more easily,
with a lesser risk of scorching (ever-present, with most
starch-thickened sauces).
Potato starch results in a clear sauce, but on the downside it does
add a recognizable flavour (as with wheat flour). Potato starch is
seldom used in North America, and would be most commonly found in
ethnic restaurants and/or markets. As with other less-common items,
the cost would be higher.
Tapioca
_______
Tapioca is most often used in puddings, although avant-garde chefs
have become more interested in it of late (Thomas Keller of the French
Laundry uses it, for example). Tapioca starch is made up of rather
long molecules, and when used as a powder tends to become unpleasantly
stringy. Because of this, it is usually employed in the form of small
spheres ("pearls") of varying sizes.
Tapiocal yields a transluscent end product, which is stable unless
overcooked. It has an especially neutral flavour, which makes it
useful in special applications. Although primarily utilized in
dessert applications, tapioca's lack of inherent flavour leaves the
door open to some innovation with savoury dishes. Tapioca is not
expensive, but is not widely found in restaurant kitchens except at
the higher levels.
Other Starches
______________
As noted above, there are any number of starches utilized in various
corners of the world, but only a small handful are generally found in
the Western kitchen. You may occasionally find others used in various
ethnic restaurants or enclaves. Starches derived from millet, water
chestnuts, sweet potatoes/yams, ginger, lotus root, or kudzu tubers
are used in Asia, for example, but the likelihood of encountering them
anywhere but an ethnic restaurant or market are very low.
Gels and Proteins
=================
The long molecules of proteins immobilize water in a rather simple
way. Essentially, they behave like a logjam. As the molecules
straighten and lengthen in the presence of heat and moisture, they
begin to collide with each other and form tangled masses, which
essentially immobilize the water by blocking its path (imagine a river
diverted into a system of weirs, if you wish). The resulting
substance is referred to as a "gel," something which is not quite
liquid *or* solid.
Many gels, and the proteins which produce them, have culinary
importance. I will start with the most fundamental, gelatin.
Gelatin
_______
A large percentage of sauces in the classic repertoire are derived
from stocks. Stocks are flavourful liquids created by simmering a
combination of bones and meat with aromatics such as onions, celery,
parsley stems, and peppercorns (there are an infinite number of
variations, as always). A successful stock demonstrates a rich, clean
flavour, derived from the meat; and a rich mouthfeel, or body, derived
from the bones (and sometimes additional items such as calves' or
pigs' feet).
The property which gives the stock its body is the one we're after,
here. A type of connecting tissue known as collagen is contained in
the bones, joints, skin, and connective tissue of animals and fish.
When collagen molecules, when heated in a liquid, unwind from their
normal helix shape and dissolve into the liquid to become individual
chains of proteins. We refer to these chains as gelatin.
These molecules of gelatin, then, are what thicken and enrich the
stock, providing its impression of body and its mouthfeel. To make a
very rudimentary sauce, it is necessary only to reduce a stock to the
point that it thickens to a desired degree. These tend to be rather
bland, though, which is why the classical repertoire contains so many
hundreds of ways to augment the basic stock.
In any case, stock and its reductions (such as demi-glace or glace de
viande, varying concentrations of basic stocks) provide the basis for
a wide variety of sauces; most of which will be finished by means of
one or another of the methods given above. In a higher-end restaurant
of the old school, a stock-based sauce might be mounted with butter;
in a lower-end restaurant it might be finished with a cornstarch
slurry.
Stocks are made in-house in a large percentage of restaurants, but
glace and demi-glace are less common, because of the investment in
time and labour they represent. For this reason, they are frequently
purchased. While not cheap, they are usually cheaper than tying up a
stove and a cook for a large number of hours.
Gelatin may, of course, be purchased as a separate product, and
utilized independently of the meat broth from which it derives. In
practice, gelatin is primarily utilized in desserts and dessert
sauces, because it has the unfortunate characteristic of breaking back
down into a liquid when heated. Cold applications, therefore, are the
best use for gelatin-based sauces. It may seem strange to think of a
gel as a sauce, but is still essentially a liquid (if an immobile one)
which may be used to enrobe a foodstuff. Traditionally gelatin-based
sauces such as aspic and chaud-froid are used in buffet settings,
where they protect the food from drying up and provide a clean, glossy
finish.
When purchased separately, gelatin is an inexpensive ingredient. It
does not affect the flavour of a dish, though of course its influence
on texture is profound and occasionally disagreeable. Gelatin is
found in a high percentage of kitchens, though most usually those with
a focus on desserts or (like hotels) a booming banquet business.
Other Protein thickeners
________________________
The role of egg yolks as a thickener/stabilizer has already been
discussed; these are gelatin's only real rival for widespread use.
Having said that, there are a few other protein-based thickeners which
have application within the kitchen.
Liver is occasionally used in Europe as a sauce ingredient, in
applications where its strong flavour is an asset rather than a
liability. It is not an especially convenient thickener to use, as
the proteins in question are locked away within the liver cells. This
means the cook must puree the liver and then strain out the connective
tissues, before use. Given the inconvenience and limited versatility,
you are unlikely to encounter liver as a thickener in North Ameria.
Blood, likewise, is used in many countries as a thickener or as a
foodstuff in its own right. Blood is traditionally used to thicken
coq au vin, for example, and many European game dishes. Again, you
are unlikely to see this in North America (especially beef blood, in
the wake of the BSE crisis).
Various shellfish, such as lobster and sea urchins, yield tissues
(eggs, liver, etc) which may be used to thicken sauces. These make a
fragile sauce, and are usually added after the dish has been removed
from the heat.
All of these are uncommon in North America, with the seafood tissues
being the one you'll find most often. These thickeners are relatively
expensive, and will not normally be found outside of the fine-dining
realm.
Dairy Thickeners
================
Dairy products, on the other hand, are not so rare. Milk-derived
thickeners are technically, proteins, but are distinctive enough to
justify their own category. We have already discussed the use of
cream, in an earlier section, so I will not reiterate that here.
Yogurt
______
Yogurt is a significant sauce ingredient from the Middle East through
Central Asia and into India. The proteins in yogurt are already
coagulated by an acidic bacterial culture, so they do not thicken a
sauce in the same way as gelatin, by binding up the free liquids
directly. Instead, yogurt lends its own thickness as it is stirred
into the sauce; essentially forming a sauce of flavoured diluted
yogurt rather than thickened liquid. Most recipes from these regions
specify yogurt which has been drained of its whey by hanging overnight
in a cloth bag (or by purchasing the commercial equivalent). These
work better, for the simple and sufficient reason that they are
thicker.
Yogurt is only moderately satisfactory as a stabilizer for a sauce.
It is limited to temperatures well below boiling, as it will otherwise
"break" and spoil the sauce. This may be dealt with in two ways;
either by adding the yogurt afer a dish is finished, or by adding
cornstarch or egg whites to the cold yogurt as a secondary
stabilization. Yogurt sauces are best eaten immediately, rather than
held or reheated.
Yogurt (like other dairy products) has a clear impact on the colour
and flavour of a sauce. While the tanginess of yogurt unsuits it for
some applications, dishes are generally constructed around it with
complementary flavours. The colour, likewise, will be pale and
sometimes murky. Yogurt works best in conjunction with ingredients
(saffron, turmeric, tomato) which provide a strong enough colour to be
appealing in the end result.
Yogurt is widely available and, though more expensive than starch
thickeners, is still reasonable. Its use is not common outside ethnic
restaurants, though some chefs are beginning to experiment with it
more.
Sour Cream and Creme Fraiche
____________________________
Sour cream and creme fraiche are very similar products. Both are made
from heavy cream, "set" to a thick consistency by a bacterial culture.
The difference is that the bacteria used in sour cream created a
tangy, more acidic end product. Both add a significant degree of
richness and body to a sauce, although as with yogurt the colour and
flavour are immediately affected.
Sour cream, like yogurt, will "break" at temperatures below boiling.
Generally, then, it will be added after a dish is removed from the
heat. Sauces made in this way do not hold well, and are best eaten
immediately rather than being held or reheated. Sour cream tends to
be used most in the cuisine of Eastern Europe, with Beef Stroganoff
being perhaps the best-known example.
Creme fraiche is a more versatile sauce ingredient, for two reasons.
One is that it lacks the distinctive tanginess of sour cream, making
it more neutral and therefore more versatile. The other is that it
does not curdle or "break" when heated, meaning it can be cooked into
a sauce. Creme fraiche thickens primarily by dilution, like yogurt or
sour cream, although its proteins provide a small quantity of
conventional thickening as well. It is used both in savoury and sweet
applications, though its use in sauces is more common on the savoury
side.
Sour cream is relatively cheap and widely available. Creme fraiche is
less so, in North America, being found in specialty or "gourmet"
retailers and wholesalers at a correspondingly higher price (though I
was dumfounded, just now, to find it at my local convenience
store...). Sour cream, as noted above, is found primarily in
restaurants of the Central and Eastern European variety; while creme
fraiche is common to fine-dining restaurants everywhere.
Cheeses
_______
Cheeses are closely related to yogurt and sour cream, in that they are
all cultured milk products. In the case of cheeses, we actually have
three different styles which are used in different ways (and again, I
am oversimplifying to a grotesque degree...but there are only three
broad classes which need concern us).
The first type of cheeses are the "fresh" cheeses, commonly known as
farmer cheese, queso fresco, and so on. These are simply fine curds
from which the whey has been drained, a product very similar to the
drained yogurt mentioned above. Fine-textured cheeses like these (and
our old supermarket friend, cream cheese) are the best thickeners,
because their relatively small grains of coagulated protein disperse
relatively well throughout a sauce without forming large unsightly
strings (beautiful on a pizza, annoying in a sauce).
Like yogurt or sour cream, these make unstable sauces which are not
suited for long periods of holding at service temperature. They are
also tricky for reheating on the stovetop, but may sometimes be used
in baked dishes to great effect. Sauces of this type have a mild,
rich flavour which lends itself well to vegetable dishes.
These cheeses tend to be harder to find than most, and therefore
pricier, with the exception of mass-market cream cheese.
The second type of cheeses are what we may term, for our purposes,
"slicing" cheeses. This includes soft (Brie), semisoft (Port Salut)
and hard (Cheddar) cheeses. I group them, despite their wide range of
differences, because they are used in much the same way.
These cheeses are seldom the sole thickener in a sauce. They will
more often be added to a base sauce (typically Bechamel, a
starch-thickened milk-based white sauce) in order to provide a more
flavourful and full-bodied end product. This is the cheddar sauce
used in our beloved macaroni and cheese, for example; or the Sauce
Mornay of the classic repertoire (when Gruyere is used instead).
These sauces have excellent body and flavour, since the cheese is a
flavouring ingredient as well as a (modest) thickener; though they are
correspondingly less versatile in their usage. These are especially
heat-sensitive, the cheese must be added after the sauce has been
removed from the heat and permitted to cool slightly. Otherwise, they
may form the long cheesy strings mentioned above.
Again, these sauces are best when served immediately. They may also be
held for days under careful refrigeration, then gently reheated
(again, baked dishes are ideal here). These are the most widespread
of cheeses, and run the gamut of pricing from generic bulk cheddar
(dirt cheap, and deservedly so) to the finest and costliest of
artisanal product. It is a rare restaurant indeed that does not have
at least one of these cheeses on hand.
The third type of cheese is the hard, dry "grating" cheeses.
Representative examples are Asiago, Dry Jack, and the king of them
all, Parmigiano-Reggiano. In practice, these are used identically to
the "slicing" cheeses mentioned above, but there are differences. The
most important is that these cheeses, because of their dryness,
provide additional thickening power. The process is simple; by
absorbing liquid from the sauce they concentrate the remainder. These
cheeses also have some of the strongest and most pungent flavours,
increasing their desirability but limiting their versatility.
Sauces deriving from these cheeses have similar attributes to those
given above, which I will not reiterate. While some of these cheeses
are rare and hard to find, others are widespread. Cost will vary
widely, with bulk industrial "parmesan" representing the low end of
the price spectrum and Parmegiano-Reggiano the high end.
Non-Protein Gels
================
Having departed from gels for a time, in order to round out our
discussion of protein thickeners, we will now to return to gels and
consider those which are not proteins. There are a number of them,
which find varying degrees of use in the professional kitchen.
Agar Agar
_________
Agar is a thickening ingredient derived from several forms of red
algae common in Asia, where solid chunks of it are often simply sliced
and used as an ingredient in salads or served on its own with a sauce.
Because it is plant-derived, agar is widely used by those who for
personal/ethical/dietary reasons (vegetarians, vegans), or for
religious ones (Jews, Muslims), eschew pork-derived commercial
gelatin.
Agar is used by soaking in cold water, and then bringing to a boil.
When cooled, agar will set nicely at about 110F. Unlike gelatin,
though, which sets and remelts at about the same temperature, agar
will only remelt at about 185F. This has distinct ramifications for
its use in the kitchen. First, agar gels will not melt in the mouth
and must be chewed. Secondly, leading chefs (most notably
trendsetting Catalan chef Ferran Adria) are now using this
characteristic to make gels which become part of a hot dish, lending
textural interest.
Agar gels are not as clear as gelatin gels, having a slight degree of
opacity, and are firmer. Like refined gelatin, it is seldom used in
conventional sauces, but may be used in desserts or the traditional
buffet applications where gelatin would normally be used.
Pseudo-aspics and chaud-froids of this type are often used when
catering to mixed crowds, in order to avoid "pork issues."
Agar is not difficult to find in most urban centres, and although more
expensive than conventional gelatin it is still not unreasonably
priced.
Carageenan
__________
Carageenan is a thickening ingredient derived from a seaweed, commonly
known in the English-speaking world as "Irish Moss." In its natural
form, the seaweed has been used for centuries to thicken soups (China)
or to make milk-based puddings (UK). You will not find this in many
restaurants, although there is certainly scope to experiment with it.
One suspects that somewhere, even as we speak, an ambitious young
molecular gastronomer is hunched over a pot in his kitchen...
Irish Moss is seldom seen in its native state outside of the areas in
which it is harvested. It should be possible to find, in our
'net-connected world, for any chef who wishes to order it; the cost
would vary with shipping. Carageenan in this form makes a soft gel,
depending how much seaweed you use, and is well-suited to dessert
sauces.
Commercially-extracted carageenan is used primarily in industrial
applications, where it can be formulated to provide gels ranging from
from very soft to downright brittle. Its use "in the field," if you
will, is limited at best.
Alginates
_________
Alginates are, like carageenan, derived from various seaweeds. They
have the interesting characteristic of forming gels only in the
presence of calcium (in milk or cream, for example). These are
little-used in the commercial kitchen, and are correspondingly
expensive. They do have the potential for some interesting effects,
however. Some avant-garde chefs have created calcium-free solutions
of suitable flavour and colour, and then dripped them into a calcium
solution, thereby creating small spheres or strings of gels.
Alginates are decidedly an avant-garde product, seldom seen outside of
commercial applications or kitchens devoted to molecular gastronomy.
Pectin
______
Pectin is a gelling carbohydrate found in varying concentrations in
fruits and vegetables. While it is rare to find a sauce in the
savoury kitchen which uses pectin (the lack of sugar means that pectin
in vegetable purees provides only a mild thickening effect), the
fruit-based "coulis" used for many desserts are thickened this way.
Pectin forms a gel when it is heated to a boil in the presence of
certain proportions of sugar and acidity, and then allowed to cool
somewhat. Fortunately, those proportions of sugar and acidity
generally correspond to what we humans find palatable!
Fruit-based, pectin-thickened sauces may be made in two ways. If we
are starting with fruits which are high in pectin (apples, quinces,
cranberries, raspberries), we may simply add sugar and cook them until
we reach the desired consistency. If using fruits with less natural
pectin (peaches, say) we must add pectin to them, either in the form
of a fruit with a complementary flavour or in the form of
commercially- refined pectin. This, then, will be balanced with a
suitable quantity of sugar and/or acidity, and then cooked down as
previously stated.
Because gels set with pectin quickly become liquid when warmed, these
sauces are generally utilized when cold. Typically we would find
these on dessert plates, though occasionally they may be utilized in
savoury dishes for their complementary flavour and colour. Pectin
gels tend to be as clear as the fruit source; opaque for crushed fruit
and crystalline for clarified fruit juices. Pectin has no discernible
flavour, although if over-used the texture may become unpleasant to
some.
Fruits themselves vary widely in price, but are generally available to
any restaurant at a reasonable price. Commercially-prepared pectin is
also inexpensive.
Miscellaneous Techniques and Ingredients
========================================
Having now worked our way through the major families of thickeners and
stabilizers, we are now entering into the homestretch of our
discussion. Here at the end, I'll discuss a grab-bag of techniques
and ingredients which have not fallen into the previous categories.
I'll begin with three of the oldest styles of thickening, in
decreasing order of obsolescence.
Bread
_____
Bread-thickened sauces are the mainstay of the oldest European
cookbooks, dating from the late Middle Ages and early Renaissance.
Typically, stale bread would be moistened and then wrung dry, and
placed in a large mortar. The liquid ingredients of the sauce would
then be dribbled slowly into the mortar, while the pestle was plied
energetically (by one's apprentice, it is to be hoped) until the
desired consistency was reached.
There are relatively few survivals of this technique in today's
kitchen, although a few persist in the Mediterranean regions. A
garlicky Spanish version of mayonnaise, alioli, is made in this way;
as are a few soups in Portugal and Italy. Bread is, of course, cheap
and widely available. Sauces thickened this way would be opaque and
be clearly flavoured by the bread; therefore it is to be suspected
that this technique would be used (if at all) either for deliberate
effect, or in a traditional European preparation such as those listed
above.
Nuts
____
Nut-thickened sauces have been used for longer than we've been making
cookbooks, so their origins are lost. Their European heyday occurred
during the Middle Ages, when almond-based sauces in particular were
popularized by the Moorish conquerors in Spain, and the Arabs in
Sicily. Ground nuts (and sometimes seeds) thicken a sauce both by the
emulsion of their oils, and by absorption of liquid into their dry
particles.
Almonds are still widely used for this purpose in classic
Mediterranean sauces such as romesco and picada, while pumpkin seeds
may give body to a Mexican mole and coconut serves the same purpose in
many tropical dishes. Although none of these are widely prepared in
North American restaurants, your chances of seeing a nut-thickened
sauce are considerably higher than those of seeing a bread-thickened
sauce.
Nuts, of course, do not make a clear sauce. For this reason, they are
best used in highly coloured sauces (romesco, mole). Their flavours
also are a direct component in the end result, increasing their
desirability while reducing their versatility. Nuts are easily
obtained anywhere across North America, and although more costly than
most thickeners are not usually exorbitant in price.
Two other nut-based thickeners deserve mention here. One is almond
milk, a milk-like substance obtained by steeping ground almonds in hot
water and then straining it off. The rich liquid obtained by this
method was a widely-used substitute for milk on fast days during the
middle ages. Its proteins will coagulate and thicken in much the same
way as those in cream. Almond milk is typically used now in desserts,
although there is no reason not to use it (creatively) in savoury
dishes. Almond milk is not difficult to make, but can be purchased if
necessary. It is not easy to find as a retail product, and is used in
few kitchens.
The second of these thickeners is nut butters, of which peanut butter
is the most widely-used. These thicken partly by lending their own
thickness to the sauce (like yogurt or creme fraiche), and also by the
emulsification of their oils. Peanut butter is often used to make
asian-styled sauces and marinades, such as satay sauce. Sesame butter
(tahini)is widely used in the Middle East, in sauces such as tarator.
In each case, the nut butter will yield a substantial and opaque sauce
with a pronounced flavour. Common butters such as peanut butter and
tahini are inexpensive and easily obtained.
Spices
______
Many cuisines around the world use spices as a thickener in sauces.
We have already discussed the virtues of mustard seeds as a thickener,
but most dried spices will make a contribution if used in quantity.
It will come as no surprise, then, that spice-heavy cuisines tend to
derive much of their thickening from this source. Turmeric, cinnamon,
cumin, and coriander are all capable thickeners. Chili peppers are
especially so, given their high pectin content. Fenugreek seeds,
much-loved in Indian and Yemeni cooking (for example) exude a
thickening gum when heated and moistened. File powder, made of ground
sassafrass leaves, thickens and flavours Louisiana gumbo. Paprika is
a common factor in Spanish and Hungarian sauces.
As thickeners, spices are limited in a number of ways. Generally they
are not capable of thickening a sauce completely on their own, and are
reinforced with other thickeners. They also, of course, add pungent
flavours and (sometimes) vigourous colours. This is not necessarily a
liability, but spices must be handled with care; obviously not every
sauce is a candidate for this technique.
Spices are widely available, and in general are not especially
effective. They are used in restaurants at all levels.
Purees
______
Purees are another widely-used thickening ingredient. Purees of fruit
are often utilized as dessert sauces, while pesto (at once a puree, an
emulsion with olive oil, a nut-thickened sauce, and a cheese-thickened
sauce) is a paste made primarily of fresh basil leaves.
For our purposes, though, we will mainly consider the use of cooked
vegetable purees. Many vegetables contain useful quantities of starch
or pectin. Chili peppers, as mentioned above, are high in pectin, and
jalapeno jelly (to pick just one example) has become a popular
condiment.
Purees tend to make grainy and rustic sauces. Often this effect is
accentuated by leaving chunks of the main ingredient for textural
contrast; applesauce is an easy example of this. Overall, most purees
thicken by adding solids, much like a river loaded with silt. It is
not an elegant technique, but it can be effective. Starchier
vegetables, like winter squash, may rise to a degree of smoothness
when judiciously mixed with cream or a Bechamel sauce.
Purees of legumes (lentils, split peas, etc) are a common feature in
the sauces of India, especially. Indian cuisine boasts a staggering
repertoire of dishes (dhals) in which the base is one or another
legume cooked or pureed to a thicker or thinner paste, and served as
part of a full meal with rice or bread.
Tomato puree and paste are the most widely-used examples of purees in
North America, being a common ingredient in any number of sauces.
They thicken by dispersion of particles, like any other puree, and
also because of a significant quantity of soluble pectin.
Purees in general are inexpensive, at least if they are made in-house
and use seasonal ingredients. They will have a profound effect on the
colour and flavour of the sauce, and the sauce will be entirely
opaque. As previously mentioned, this suits purees best to rustic or
ethnic preparations. Purees are widely used in restaurants of all
types.
Foams, Traditional and Modern
_____________________________
The final means of thickening we will discuss is thickening by way of
foaming, or bubbles. Bubbles are a rather odd approach to thickening;
the introduction of air bubbles interferes with the movement of water
molecules in the same way that particles of starch or puree would do.
We are all familiar with many foam-thickened preparations. Whipped
cream, anyone? Meringue? These are familiar in every home, and you
may not think of them as sauces, but they do answer fairly well to the
definition laid out above. More formal sauces, such as
sabayon/zabaglione, utilize much the same principle.
Foam sauces are, by their nature, more or less ephemeral (literally!).
For anything other than immediate use, they require stabilization.
Most of the stabilizers we've discussed above are applicable,
including starch, pectin, and gelatin. Egg yolks are trickier,
because of their fat content: fat is a foam-killer under ordinary
circumstances. Anyone who's ever tried to whip egg whites which have
gotten yolk in them will attest to that. However, if the yolks are
previously emulsified (into a custard, for example), they work just
fine. This is, in fact, exactly how souffles are made.
In recent years, less traditional foams have become commonplace.
First popularized by Ferran Adria, foams are now made of almost any
ingredient imaginable - cod, asparagus, foie gras - and spooned onto
the plate or added to an existing sauce. Any water-based liquid or
semisolid may be used in this technique: just whisk or "blenderize"
the liquid until it froths, and spoon off the froth. This is,
obviously, a sauce to be used a la minute, as its lifespan is only a
few minutes.
Foam-based sauces may be fragile (Adria-style foams) or durable
(sabayon) as desired. The ingredients are generally inexpensive and
readily available to any chef.
=====================================================================================
This concludes my discussion of the various thickeners available for
use in today's commercial kitchen. Although I've tried to be
comprehensive, I have surely missed a few; I will cheerfully address
any specific examples you wish to bring up. By the same token, if I
wake up tomorrow and ask myself "How did I forget 'X'," I will append
it to this answer.
====================================================================================
Resources
In this particular instance, I relied almost entirely on printed resources.
On Food and Cooking: The Science and Lore of the Kitchen, Harold S
McGee, revised (2004) edition
This is the motherlode for anyone interested in the science of food.
All 800+ densely-packed pages are pure gold to any cook. His
discussion of sauces is much lengthier and more detailed than mine,
and should yield much information of considerable interest to you.
The original 1984 edition sparked the current "molecular gastronomy"
movement.
Professional Cooking, Wayne Gisslen, John Wiley & Sons, 5th (Canadian) ed. 2003
For a more pragmatic discussion of sauces and their characteristics,
this textbook or one of its counterparts is a valuable mine of
ingredients and technique.
A Return to Cooking, Eric Ripert & Michael Ruhlman, Artisan, 2002
Although I've only paraphrased one reference from this book, it may be
of some interest to you. Ruhlman, as an interested observer, follows
Ripert through a year of cooking to please himself (something the
executive chef seldom gets to do). There are many insights to be
gleaned, and Ruhlman has enough kitchen experience to report
accurately on what he sees.
A Drizzle of Honey, David M Gitlitz and Linda Kay Davidson, St
Martin's Griffin, 1999
A reconstruction of the cuisine of the converted Jewish community in
Spain, at the time of the Inquisition's rise. This is a serious
treasure trove of vintage recipes in modern language and measures,
including many nut-thickened sauces. A good red, in its own right.
The Saucier's Apprentice, Raymond Sokolov, Knopf, 1976
Although I did not draw on it in constructing this answer, there are
few better introductions to saucemaking in the French tradition.
Finally, for ongoing insight into the evolution of ingredients and
techniques, there are few tools better than a good online forum of
like-minded individuals. As mentioned in the previous answer I'd
completed for you, I spend much of my online time at
http://www.egullet.org
Thank you again for an interesting (if exhausting) question, and a
further opportunity to talk about my favourite subject. If you
require further detail or amplification of any point, by all means
just ask.
-Chromedome |
