Thickening agent
From Freepedia
Thickening agents, or thickeners, are substances which, when added to the mixture, increase its viscosity without substantially modifying its other properties, like eg. taste. They provide body, increase stability, and improve suspending action. Thickening agents are often food additives.
Thickeners are frequently based on polysaccharides (starches or vegetable gums) or proteins (egg yolks, demi-glaces, collagen).
Common examples are agar, alginin, arrowroot, collagen, cornstarch, fecula, gelatin, guar gum, katakuri, locust bean gum, pectin, roux, tapioca, and xanthan gum.
Flour is often used for thickening gravies, gumbos and stews. Roux, a mixture of flour and fat, is used for gravies and stews. Cereal grains (oatmeal, couscous, farina...) are used to thicken soups. Yoghurt is popular in Eastern Europe and Middle East for thickening soups. Soups can also be thickened by grated starchy vegetables. Egg yolks have rich flavor and offer velvetty smooth texture, but are tricky to use. Pectin is used as gelling agent for jams and jellies. Other thickeners used by cooks are nuts, or glaces made of meat or fish.
For acidic foods arrowroot is better choice than cornstarch, which loses thickening potency when mixed with acids. Cornstarch is also worse choice than tapioca or arrowroot when the food is to be frozen, as frozen cornstarch becomes spongy.
Avoid overcooking. Some starches, when cooked for too long or at too high temperature, degrade and lose thickening potential.
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