Thickening agent

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Potato starch slurry Potato starch slurry.jpg
Potato starch slurry
Roux Roux bianco.JPG
Roux

A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. Edible thickeners are commonly used to thicken sauces, soups, and puddings without altering their taste; thickeners are also used in paints, inks, explosives, and cosmetics.

Contents

Thickeners may also improve the suspension of other ingredients or emulsions which increases the stability of the product. Thickening agents are often regulated as food additives and as cosmetics and personal hygiene product ingredients. Some thickening agents are gelling agents (gellants), forming a gel, dissolving in the liquid phase as a colloid mixture that forms a weakly cohesive internal structure. Others act as mechanical thixotropic additives with discrete particles adhering or interlocking to resist strain.

Thickening agents can also be used when a medical condition such as dysphagia causes difficulty in swallowing. Thickened liquids play a vital role in reducing risk of aspiration for dysphagia patients. [1]

Many other food ingredients are used as thickeners, usually in the final stages of preparation of specific foods. 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.

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 better choice 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 to be frozen, tapioca or arrowroot are preferable over cornstarch, which becomes spongy when frozen.

Types

Food thickeners frequently are based on either polysaccharides (starches, vegetable gums, and pectin), or proteins.

Starches

This category includes starches as arrowroot, cornstarch, katakuri starch, potato starch, sago, wheat flour, almond flour, tapioca and their starch derivatives.

A flavorless powdered starch used for this purpose is a fecula (from the Latin faecula, diminutive of faex, "dregs").

Other polymers

Other sugar polymers include vegetable gums such as pectin from Citrus peel, guar gum from the guar bean, and locust bean gum from the carob bean.

Agar, alginin and carrageenan are polysaccharides extracted from algae, xanthan gum is a polysaccharide secreted by the bacterium Xanthomonas campestris , and carboxymethyl cellulose is a synthetic gum derived from cellulose. Proteins used as food thickeners include collagen, egg whites, and gelatin. Other thickening agents act on the proteins already present in a food; for example sodium pyrophosphate, which acts on casein in milk during the preparation of instant pudding.

Gelling agents

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

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

Examples are:

Commercial jellies used in East Asian cuisines include the glucomannan polysaccharide gum used to make "lychee cups" from the konjac plants, and aiyu or ice jelly from the Ficus pumila climbing fig plant.

Agar-agar produces a very clear gel with light residual taste. Gelatin sheets disperse easily with no residual taste, but powdered form may have some taste. Kappa carragreenan may include potassium chloride to improve the gelling process and produces a clear product with very little aftertaste. Iota carrageenan contains sodium chloride which improves gel formation. Sodium alginate produces a medium viscosity gel but may have some aftertaste. High-methoxy pectin is one of the most widely used gelling agents in food processing. It reacts with some sugars and acids and sometimes includes minerals to improve gelling process. Low-methoxy pectin reacts with calcium, and is used for the preparation of low sugar jams. [2]

Flours

Functional flours are produced from specific cereal variety (wheat, maize, rice or other) conjugated to specific heat treatment able to increase stability, consistency and general functionalities. These functional flours are resistant to industrial stresses such as acidic pH, sterilisation, freeze conditions, and can help food industries to formulate with natural ingredients. For the final consumer, these ingredients are more accepted because they are shown as "flour" in the ingredient list.

Flour is often used for thickening gravies, gumbos, and stews. The most basic type of thickening agent, flour blended with water to make a paste, is called whitewash. [3] It must be cooked in thoroughly to avoid the taste of uncooked flour. Roux, a mixture of flour and fat (usually butter) cooked into a paste, is used for gravies, sauces and stews. Cereal grains (oatmeal, couscous, farina, etc.) are used to thicken soups. Yogurt is popular in Eastern Europe and Middle East for thickening soups. Soups can also be thickened by adding grated starchy vegetables before cooking, though these will add their own flavour. Tomato puree also adds thickness as well as flavour. Egg yolks are a traditional sauce thickener in professional cooking; they have rich flavor and offer a velvety smooth texture but achieve the desired thickening effect only in a narrow temperature range. Overheating easily ruins such a sauce, which can make egg yolk difficult to use as a thickener for amateur cooks. Other thickeners used by cooks are nuts (including rehan) or glaces made of meat or fish.

In cooking

Many thickening agents require extra care in cooking. Some starches lose their thickening quality when cooked for too long or at too high a temperature; on the other hand, cooking starches too short or not hot enough might lead to an unpleasant starchy taste or cause water to seep out of the finished product after cooling. Also, higher viscosity causes foods to burn more easily during cooking. As an alternative to adding more thickener, recipes may call for reduction of the food's water content by lengthy simmering. When cooking, it is generally better to add thickener cautiously; if over-thickened, more water may be added but loss of flavour and texture may result.

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

Mechanical and thixotropic agents

Fumed silica and similar products form stiff microscopic chains or fibers which interlock or agglomerate into a mass, holding the associated liquid by surface tension, but which can separate or slide when sufficient force is applied. This causes the thixotropic or shear-thinning property (also frequently exhibited by gels), where the viscosity is non-Newtonian and becomes lower as the shearing force or time increases; their usefulness is primarily that the resulting increase in viscosity is large compared to the quantity of silica added. Fumed silica is generally accepted as safe as a food additive [4] and is frequently used in cosmetics. Additives such as precipitated silica, fine talc, or chalk also meet the definition of thickening agent in that they increase viscosity and body while not affecting the target property of a mixture.[ citation needed ]

Cosmetics

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

Paint and printing thickeners

One of the main use of thickeners is in the paint and printing industries, which depend heavily on rheology modifiers, to prevent pigments settling to the bottom of the can, yielding inconsistent results. Water based formulas would be nearly impossible with the exception of India ink and the few other water-soluble pigments, but these would have very little coverage and at best would stain wood slightly. All modern paints and inks will have some pigment added at the factory for opacity and to control the specularity of the finish, from matte to high gloss, dependent on thickener used, but more so on the size of the particles added as opacity modifier. Particle sizes of 1  µm and below will be the limit of high gloss, probably confined to luxury automotive coatings, and about 100 µm particulates will make a bumpy surface on the microscopic scale, which scatters light and makes the surface appear matte.[ citation needed ]

Rheology modifiers in common use:

All of the above rheology modifiers are used in the 0.2% to 2.0% range

Petrochemistry

In petrochemistry, gelling agents, also called solidifiers, are chemicals capable of reacting with oil spills and forming rubber-like solids. [6] The gelled coagulated oil then can be removed from the water surface by skimming, suction devices, or nets. Calm or only moderately rough sea is required.

Flame fuel thickening compounds

Napalm gel concentration and rheology - Napalm thickener is an impure hydroxyaluminum di-soap. Napalm gel concentration and rheology.png
Napalm gel concentration and rheology - Napalm thickener is an impure hydroxyaluminum di-soap.

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

Many fuels used in incendiary devices require thickening for increased performance. Aluminium salts of fatty acids are frequently used. Some formulations (e.g. Napalm-B) use polymeric thickeners. Thickened pyrophoric agent, a pyrophoric replacement of napalm, is a triethylaluminium thickened with polyisobutylene.

Fuel thickeners are mostly composed of the same thickeners as polar liquids (water), due to the fact that they are "bipolar", that is, they have a polar and an apolar group. The only change is in the orientation of these groups. In the non-polar medium reverse micelle formation occurs.

Because the hydrocarbon-hydrocarbon type intermolecular interactions are the weakest, the reverse micelle is much more unstable than the normal micelle. The main gelled fuel precursors are commonly derived from weak acids and strong or weak bases.

See also

Related Research Articles

<span class="mw-page-title-main">Agar</span> Thickening agent used in microbiology and food

Agar, or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from "ogonori" (Gracilaria) and "tengusa" (Gelidiaceae). As found in nature, agar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta phylum. The processing of food-grade agar removes the agaropectin, and the commercial product is essentially pure agarose.

<span class="mw-page-title-main">Gelatin dessert</span> Dessert made with gelatin

Gelatin desserts are desserts made with a sweetened and flavoured processed collagen product (gelatin). This kind of dessert was first recorded as jelly by Hannah Glasse in her 18th-century book The Art of Cookery, appearing in a layer of trifle. Jelly is also featured in the best selling cookbooks of English food writers Eliza Acton and Isabella Beeton in the 19th century.

<span class="mw-page-title-main">Polysaccharide</span> Long carbohydrate polymers such as starch, glycogen, cellulose, and chitin

Polysaccharides, or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes as catalyst, which produces constituent sugars. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch, glycogen and galactogen and structural polysaccharides such as cellulose and chitin.

Rheology is the study of the flow of matter, primarily in a fluid state, but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. Rheology is a branch of physics, and it is the science that deals with the deformation and flow of materials, both solids and liquids.

<span class="mw-page-title-main">Guar gum</span> Vegetable gum from the guar bean, Cyamopsis tetragonoloba

Guar gum, also called guaran, is a galactomannan polysaccharide extracted from guar beans that has thickening and stabilizing properties useful in food, feed, and industrial applications. The guar seeds are mechanically dehusked, hydrated, milled and screened according to application. It is typically produced as a free-flowing, off-white powder.

<span class="mw-page-title-main">Dietary fiber</span> Portion of plant-derived food that cannot be completely digested

Dietary fiber or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by their solubility, viscosity, and fermentability, which affect how fibers are processed in the body. Dietary fiber has two main components: soluble fiber and insoluble fiber, which are components of plant-based foods, such as legumes, whole grains and cereals, vegetables, fruits, and nuts or seeds. A diet high in regular fiber consumption is generally associated with supporting health and lowering the risk of several diseases. Dietary fiber consists of non-starch polysaccharides and other plant components such as cellulose, resistant starch, resistant dextrins, inulin, lignins, chitins, pectins, beta-glucans, and oligosaccharides.

<span class="mw-page-title-main">Pectin</span> Structural carbohydrate in the cell walls of land plants and some algae

Pectin is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal chemical component of pectin is galacturonic acid which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from citrus fruits for use as an edible gelling agent, especially in jams and jellies, dessert fillings, medications, and sweets; and as a food stabiliser in fruit juices and milk drinks, and as a source of dietary fiber.

<span class="mw-page-title-main">Carrageenan</span> Natural linear sulfated polysaccharide

Carrageenans or carrageenins are a family of natural linear sulfated polysaccharides that are extracted from red edible seaweeds. Carrageenans are widely used in the food industry, for their gelling, thickening, and stabilizing properties. Their main application is in dairy and meat products, due to their strong binding to food proteins. In recent years, carrageenans have emerged as a promising candidate in tissue engineering and regenerative medicine applications as they resemble native glycosaminoglycans (GAGs). They have been mainly used for tissue engineering, wound coverage, and drug delivery.

<span class="mw-page-title-main">Xanthan gum</span> Polysaccharide gum used as a food additive and thickener

Xanthan gum is a polysaccharide with many industrial uses, including as a common food additive. It is an effective thickening agent and stabilizer that prevents ingredients from separating. It can be produced from simple sugars by fermentation and derives its name from the species of bacteria used, Xanthomonas campestris.

<span class="mw-page-title-main">Breyers</span> Ice cream brand

Breyers is a brand of ice cream started in 1866 by William A. Breyer in Philadelphia, Pennsylvania.

<span class="mw-page-title-main">Alginic acid</span> Polysaccharide found in brown algae

Alginic acid, also called algin, is a naturally occurring, edible polysaccharide found in brown algae. It is hydrophilic and forms a viscous gum when hydrated. With metals such as sodium and calcium, its salts are known as alginates. Its colour ranges from white to yellowish-brown. It is sold in filamentous, granular, or powdered forms.

<span class="mw-page-title-main">Gellan gum</span> Gelling and thickening agent

Gellan gum is a water-soluble anionic polysaccharide produced by the bacterium Sphingomonas elodea. The gellan-producing bacterium was discovered and isolated by the former Kelco Division of Merck & Company, Inc. in 1978 from the lily plant tissue from a natural pond in Pennsylvania. It was initially identified as a gelling agent to replace agar at significantly lower concentrations in solid culture media for the growth of various microorganisms. Its initial commercial product with the trademark as Gelrite gellan gum, was subsequently identified as a suitable agar substitute as gelling agent in various clinical bacteriological media.

<span class="mw-page-title-main">Carboxymethyl cellulose</span> Cellulose derivative grafted with carboxymethyl groups

Carboxymethyl cellulose (CMC) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodium salt, sodium carboxymethyl cellulose. It used to be marketed under the name Tylose, a registered trademark of SE Tylose.

<i>Tara spinosa</i> Species of legume

Tara spinosa, commonly known as tara (Quechua), also known as Peruvian carob or spiny holdback, is a small leguminous tree or thorny shrub native to Peru. T. spinosa is cultivated as a source of tannins based on a galloylated quinic acid structure. This chemical structure has been confirmed also by LC–MS. It is also grown as an ornamental plant because of its large colorful flowers and pods.

<span class="mw-page-title-main">Modified starch</span> Thickening agent

Modified starch, also called starch derivatives, is prepared by physically, enzymatically, or chemically treating native starch to change its properties. Modified starches are used in practically all starch applications, such as in food products as a thickening agent, stabilizer or emulsifier; in pharmaceuticals as a disintegrant; or as binder in coated paper. They are also used in many other applications.

<span class="mw-page-title-main">Hydroxyethyl cellulose</span> Chemical compound

Hydroxyethyl cellulose is a gelling and thickening agent derived from cellulose. It is widely used in cosmetics, cleaning solutions, and other household products. Hydroxyethyl cellulose and methyl cellulose are frequently used with hydrophobic drugs in capsule formulations, to improve the drugs' dissolution in the gastrointestinal fluids. This process is known as hydrophilization.

<span class="mw-page-title-main">Stabiliser (food)</span> Food additive

A stabiliser is an additive to food which helps to preserve its structure. Typical uses include preventing oil-water emulsions from separating in products such as salad dressing; preventing ice crystals from forming in frozen food such as ice cream; and preventing fruit from settling in products such as jam, yogurt and jellies. Some of these food additives may promote the growth of specific microorganisms in the gastrointestinal tract that can ferment them. The following hydrocolloids are the most common ones used as stabilisers:

<span class="mw-page-title-main">Instant pudding</span>

Instant pudding is an instant food product that is manufactured in a powder form and used to create puddings and pie filling. It is produced using sugar, flavoring agents and thickeners as primary ingredients. Instant pudding can be used in some baked goods.

<span class="mw-page-title-main">Sour cream</span> Fermented dairy product

Sour cream is a dairy product obtained by fermenting regular cream with certain kinds of lactic acid bacteria. The bacterial culture, which is introduced either deliberately or naturally, sours and thickens the cream. Its name comes from the production of lactic acid by bacterial fermentation, which is called souring. Crème fraîche is one type of sour cream with a high fat content and less sour taste.

References

  1. Glassburn, Devon L.; Deem, Jodelle F. (1998). "Thickener Viscosity in Dysphagia Management: Variability among Speech-Language Pathologists". Dysphagia. 13 (4): 218–222. doi:10.1007/PL00009575. PMID   9716753. S2CID   37019709.
  2. A Chef's Guide to Gelling Thickening and Emulsifying Agentsing and Emuls. CRC Press.
  3. "The Science of Thickening Agents — The Culinary Pro". Theculinarypro.com. Retrieved 2022-05-08.
  4. "Fumed Silica MSDS". Cabot Corporation. Retrieved 20 June 2016.
  5. "Hydrolyzed Collagen". Yahoo. Retrieved 19 June 2016.
  6. Jadhav, S. R.; Vemula, P. K.; Kumar, R.; Raghavan, S. R.; John, G. (2010). "Sugar-Derived Phase-Selective Molecular Gelators as Model Solidifiers for Oil Spills". Angew. Chem. 122 (42): 7861–7864. Bibcode:2010AngCh.122.7861J. doi:10.1002/ange.201002095. PMID   20632425.