Wapedia - Wiki: Thickening agent

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"Thickener" redirects here. For a separation method see gravity separation.

Thickening agents, or thickeners, are substances which, when added to an aqueous mixture, increase itsviscosity without substantially modifying its other properties, such as taste. They provide body, increasestability, and improve suspension of added ingredients. Thickening agents are often used as food additivesand in cosmetics and personal hygiene products. Some thickening agents are gelling agents, forming a gel.The agents are materials used to thicken and stabilize liquid solutions, emulsions, and suspensions. Theydissolve in the liquid phase as a colloid mixture that forms a weakly cohesive internal structure.

Contents:1. Food2. Cosmetics3. Paint and Printing thickeners4. Petrochemistry5. Explosives and incendiaries6. See also7. External links

1. Food

Food thickeners frequently are based on either polysaccharides (starches, vegetable gums, and pectin), orproteins. A flavourless powdered starch used for this purpose is a fecula (from the Latin faecula, diminutiveof faex meaning "dregs"). This category includes arrowroot, cornstarch, katakuri starch, potato starch, sago,and tapioca. Vegetable gums used as food thickeners include alginin, guar gum, locust bean gum, andxanthan gum. Proteins used as food thickeners include collagen, egg whites, furcellaran, gelatin. Sugarsinclude agar and carrageenan. Other thickening agents act on the proteins already present in a food. Oneexample is sodium pyrophosphate, which acts on casein in milk during the preparation of instant pudding. Itexists authentic food thickener such as functional flours These functional flours are produced from specificcereal variety (wheat, maize, rice or other) conjugated to specific heat treatment able to increase stability,consistency and general functionalities. These functional flours are resistance to industrial stresses: acidic pH,sterilisation, freeze conditions, and can help food industries to formulate with natural based ingredients. Forthe final consumer, these ingredients are more accepted because they are declared as "flour" in theingredient list

Different thickeners may be more or less suitable in a given application, due to differences in taste, clarity,and their responses to chemical and physical conditions. For example, for acidic foods, arrowroot is a betterchoice than cornstarch, which loses thickening potency in acidic mixtures. At (acidic) pH levels below 4.5,guar gum has sharply reduced aqueous solubility, thus also reducing its thickening capability. If the food is tobe frozen, tapioca or arrowroot are preferable over cornstarch, which becomes spongy when frozen.

Many other food ingredients are used as thickeners, usually in the final stages of preparation of specificfoods. These thickeners have a flavor and are not markedly stable, thus are not suitable for general use.However, they are very convenient and effective, and hence are widely used.

Flour is often used for thickening gravies, gumbos, and stews. It must be cooked in thoroughly to avoid thetaste of uncooked flour. Roux, a mixture of flour and fat (usually butter) cooked into a paste, is used forgravies, sauces and stews. Cereal grains (oatmeal, couscous, farina, etc.) are used to thicken soups. Yogurtis popular in Eastern Europe and Middle East for thickening soups. Soups can also be thickened by addinggrated starchy vegetables before cooking, though these will add their own flavour. Tomato puree also addsthickness as well as flavour. Egg yolks have rich flavor and offer a velvety smooth texture but can prove tobe difficult to use. Other thickeners used by cooks are nuts (including rehan) or glaces made of meat or fish.

Many thickening agents require extra care in cooking. Some starches lose their thickening quality whencooked for too long or at too high a temperature, and thickened food may burn more easily during cooking.As an alternative to adding more thickener, recipes may call for reduction of the food's water content bylengthy simmering. When cooking, it is generally better to add thickener cautiously; if over-thickened, morewater may be added but loss of flavour and texture may result.

Wapedia - Wiki: Thickening agent

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Gelling agents are food additives used to thicken and stabilize various foods, like jellies, desserts andcandies. The agents provide the foods with texture through formation of a gel. Some stabilizers andthickening agents are gelling agents.

Typical gelling agents include natural gums, starches, pectins, agar-agar and gelatin. Often they are basedon polysaccharides or proteins.

Examples are:

Alginic acid (E400), sodium alginate (E401), potassium alginate (E402), ammonium alginate (E403),calcium alginate (E404) - polysaccharides from brown algaeAgar (E406, a polysaccharide obtained from red seaweeds)Carrageenan (E407, a polysaccharide obtained from red seaweeds)Locust bean gum (E410, a natural gum from the seeds of the Carob tree)Pectin (E440, a polysaccharide obtained from apple or citrus-fruit)Gelatin (E441, made by partial hydrolysis of animal collagen)

Extracts of plants such as konjac and Ficus pumila are also commonly made into jellies and used in manyEast Asian cuisines.

Food thickening can be important for people facing medical issues with chewing or swallowing, as foods witha thicker consistency can reduce the chances of choking, or of inhalation of liquids or food particles, whichcan lead to aspiration pneumonia.

2. Cosmetics

Thickening agents used in cosmetics or personal hygiene products include polyethylene glycol, syntheticpolymers such as carbomer (a trade name for polyacrylic acid) and vegetable gums. Some thickening agentsmay also function as stabilizers when they are used to maintain the stability of an emulsion. Someemollients, such as petroleum jelly and various waxes may also function as thickening agents in an emulsion

3. Paint and Printing thickeners

One of the main use of thickeners in the paint and printing industries, for example ( acrylic thickener ) is themain item used in both textile printing with water base and also in the water base paints. Also polyvenyle co-polimer and homopolimer is one thickener that can be used in the paint industries

4. Petrochemistry

In petrochemistry, gelling agents, also called solidifiers, are chemicals capable of reacting with oil spills andforming rubber-like solids. The gelled coagulated oil then can be removed from the water surface byskimming, suction devices, or nets. Calm or only moderately rough sea is required.

5. Explosives and incendiaries

Various materials are used to convert liquid explosives to a gel form. Nitrocellulose and other nitro esters areoften used. Other possibilities include nitrated guar gum[1].

Many fuels used in incendiary devices require thickening for increased performance. Aluminium salts of fattyacids are frequently used. Some formulations (e.g. Napalm-B) use polymeric thickeners, namely polystyrene.Hydroxyl aluminium bis(2-ethylhexanoate) is also used. Thickened pyrophoric agent, a pyrophoricreplacement of napalm, is a triethylaluminium thickened with polyisobutylene.

6. See also

Wapedia - Wiki: Thickening agent

http://wapedia.mobi/en/Gelling_agent[11/10/2010 11:23:00 AM]

Mucilage

7. External links

Cook's Thesaurus: Thickeners

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modified: 2010-10-17 13:26:37