FOOD THICKENING AGENTS
Thickening agents, or thickeners, are substances
which, when added to an aqueous mixture, increase its viscosity without
substantially modifying its other properties, such as taste. They provide body,
increase stability, and improve suspension of added ingredients.
Examples of thickening agents include:
polysaccharides (starches, vegetable gums, and pectin), proteins (eggs,
collagen, gelatin, blood albumin) and fats (butter, oil and lards).
All purpose flour is
the most popular food thickener, followed by cornstarch and arrowroot or tapioca. All
of these thickeners are based on starch as the thickening agent.
Cornstarch -- Cornstarch is actually a flour. It is the endosperm
of corn kernels that has been dried and ground. Corn starch is used as a
thickening agent in soups and liquid-based foods, such as sauces, gravies and
custard. It is sometimes preferred over flour because it forms a translucent
mixture, rather than an opaque one.
Potato starch -- Potato starch is not potato flour. Potato flour is
dehydrated potatoes ground into powder and is much heavier and denser. Potato
starch is the result of an extraction process removing the starch only from the
potato.
Tapioca --Tapioca is a starch extracted from the ground, dried
root of the cassava plant, which grows in the tropics. Tapioca does not lose
it's quality even on reheating and freezing. When tapioca starch is used as a
thickening agent, it becomes clear and completely dissolves.
Arrowroot --Arrowroot is like other pure starches, however,
arrowroot is almost pure carbohydrate and devoid of protein, thus it does not
equal wheat flour nutritionally.
Arrowroot thickens at a lower temperature than
does flour or cornstarch, is not weakened by acidic ingredients, has a more
neutral taste, and is not affected by freezing.
Rice flour-- (also rice powder) is a form of flour made from finely
milled rice. It is distinct from rice starch, which is usually produced by
steeping rice in lye. Rice flour is a particularly good substitute for wheat
flour, which causes irritation in the digestive systems of those who are gluten-intolerant.
THER POLYSACCHARIDE THICKENERS
Polysaccharides as a thickener food includes the starches, vegetable
gums and pectin. Food starch is a flavourless powder in which comes the
cornstarch, potato starch, katakuri starch.
NATURAL (VEGETABLE) GUMS
Vegetable Gums are all polysaccharides of natural origin, capable of
causing a large viscosity increase in solution, even at small concentrations.
In the food industry they are used as thickening agents, gelling agents,
emulsifying agents, and stabilizers.
Agar --Agar or agar-agar is a gelatinous substance derived from
a polysaccharide that accumulates in the cell walls of agarophyte red algae.
Historically and in a modern context, it is chiefly used as an ingredient in
desserts throughout Asia and also as a solid substrate to contain culture
medium for microbiological work.
Pectin Pectin is a kind of polysaccharide (Polymer of D-Galacturonic
Acid) that is obtained from plant such as citrus fruit peel, apple peel etc.
Pectin is a vegetable gum and food thickener that is used to make gel. In human
digestion, pectin goes through the small intestine more or less intact.
PROTEINS AS THICKENING AGENTS
Egg yolks --Egg yolks are the most efficient protein
thickeners in part because they are so concentrated with protein, have a rich
flavor and offer a velvety smooth texture. The difficulty in using egg yolks is
the small window of temperature needed to thicken the sauce or soup but not
allow the egg to set.
Collagen --a protein found in nearly all connective tissue,
when cooked it will dissolve and thicken sauces.
Gelatin - a protein produced by partial hydrolysis of collagen
extracted from the boiled bones, connective tissues, organs and some intestines
of animals.
Yogurt--Yogurt is popular in Eastern Europe and Middle East for
thickening soups
FATS AS THICKENING AGENTS
Butter is the best thickener to use for wine
and stock based sauces. Make sure that the butter is whisked in off the heat or
the emulsion can separate.