The hydrocolloids They are a large, heterogeneous group of polymeric substances that mainly include polysaccharides and some proteins. Its name derives from the Greek term hydro, which means water, and kolla, glue.
Among the carbohydrates or polysaccharides are hydrocolloids such as starch, agar, numerous gums, among others. There are also those of a protein nature of high commercial interest, such as soy protein, casein or caseinate, gelatin and egg white proteins, among others..
Hydrocolloids can have different sources: natural of vegetable origin, animal, algae, and even some synthesized by microorganisms. They can also be semi-synthetic, such as cellulose derivatives.
Hydrocolloids form viscous microscopic dispersions or gels on contact with water; that is, they are hydrophilic, which is why they are also called hydrophilic colloids. They trap water within their branched, polymeric structure.
In this way, they generate different textures, viscosity and elasticity, properties that are used in the food, pharmaceutical, medical and research industries in general..
Article index
-In their molecular structure they present a large number of hydroxyl groups (-OH. This causes them to establish hydrogen bonds with water; hence, they are hydrophilic and form colloidal dispersions when in contact with it..
-Similarly, hydrocolloids can form gels due to ionic or temperature changes..
-Due to their gel-forming, thickening, texturizing properties, among others, hydrocolloids are widely used as additives in the food industry..
-They can increase the thickness or texture of food; they serve to control the formation of ice crystals; allow varying the opacity and flavor of food.
-Hydrocolloids can be used alone and in some cases mixtures are used that offer synergistic behavior in their characteristics or properties, which increases their usefulness..
Hydrocolloids can be classified considering several criteria, such as their chemical structure, their origin, their properties, among other characteristics..
Hydrocolloids can be classified into two large groups as polysaccharides or proteins. Between polysaccharides they can be linear, like cellulose, alginates; or branched, such as starch and dextran, among others.
In addition, depending on the type of monosaccharide that makes up the polysaccharide, they can be homopolysaccharides or heteropolysaccharides.
Between the homopolysaccharides Mention may be made of starch, which is made up of long branched chains of glucose, that is, it contains the same type of monosaccharide.
Between the heteropolysaccharides or carbohydrates formed by more than one type of monosaccharides, there are hydrocolloids such as agar, gum arabic, among many others.
The group of casein, gelatin and egg white proteins, among others, are naturally protein.
According to their origin, hydrocolloids can be classified as natural -the vast majority-, as they are obtained from plants, animals, algae and microorganisms. There are some derived from natural or chemically modified derivatives, as specified below.
From the extracts of various parts of the plants, one can mention cellulose, pectin, starch, the great variety of gums such as arabic, tamarind gum, among others..
There is gelatin, casein, egg white protein, soy protein.
Of different types of algae you have for example agar, carrageenans, alginate.
Like xanthan, dextran, curdlán, swarm, among others.
Such as methylcellulose, ethylcellulose, carboxymethylcellulose, propylene glycol alginate, modified starches, among others.
Hydrocolloids are used in the food industry as thickening and gelling additives. These modify the properties such as viscosity and texture of food.
Depending on the hydrocolloid used, its concentration, the pH, the temperature and the foods in which it is used, the shelf life is increased, the quality of the food is improved and different sensations are induced in the mouth of the diners..
As thickeners for soups, sauces, toppings and salad dressing among other foods, various types of gum are used such as arabica, guar or guaran and carob, among others. Xanthan and starch are also thickeners.
Hydrocolloids such as pectin, alginate, agar, gellan and carrageenan are used as gelling agents or gel formers, mainly in jellies, jams, gelatins with little sugar and ice cream, among other foods..
There are hydrocolloids, such as agar agar, which is used in cooking by vegans to avoid the use of conventional gelatin, which contains substances of animal origin in its preparation.
Hydrocolloids such as agar are used in the preparation of different types of microbiological culture media. It constitutes the base that will give a different texture to these media, which withstand the sterilization temperatures without modifying.
As a means to carry out different chromatography and gel filtration processes, the hydrocolloid Sephadex is used, generally used in columns. This allows the separation or purification of proteins and other biomolecules based on their different size or molecular weight..
In dentistry under specific conditions, alginate and agar hydrocolloids are good materials for making dental impressions..
In medicine, hydrocolloids such as dextran, hydroxyethyl starch, gelatin, among others, are used in infusion fluids and volume expander solutions for the treatment of hypovolemia..
Hydrocolloids such as gums are used in the manufacture of bioadhesives for surgical bandages, dressings or coverings applied for the treatment of pressure ulcers and wounds..
Agar like cellulose cannot be digested by the digestive system of the human body, therefore it does not provide energy, but it serves as a fiber that retains water, which allows its use in medicines such as laxatives.
There are many examples of hydrocolloids that have been mentioned in the previous sections, among which the following can be expanded in more detail:
-The polysaccharide dextran. It is branched or cross-linked, and is formed by a large amount of glucose, used in sephadex, a gel with a spherical three-dimensional structure that has pores inside.
These spheres show variations in the crosslinking of the organic chains that make them up, obtaining different types of sephadex. The higher the crosslinking, the smaller the pore size of the sphere..
-The carrageenans, which are several types derived from galactose, include furcelarans, and are obtained from red algae of different genus and species.
-Among the variety of rubbers, it is worth highlighting as an example gum arabic, obtained from a resin extracted from various types of acacia.
-And finally among those derived from cereals are arabinoxylans, the inulin, among many other examples.
Yet No Comments