Hydrocolloids
The term hydrocolloids (from the Greek hydro “water” and kolla “glue”) encompasses a large group of polysaccharides and proteins that dissolve in water as colloids and show a high ability to form gels .
origin
Almost all hydrocolloids come from nature:
- Land plants: starch flour , cellulose , pectins (E 440), gum arabic (E 414), galactomannans such as guar gum (E 412), carubin (E 410) from the carob tree and konjac (E 425) from the devil's tongue and many others
- Algae: agar (E 406), carrageenan (E 407), alginates (E 400 – E 404)
- Animals: gelatine , caseinates and many more.
- Bacteria: xanthan (E 415), dextrans , scleroglucan .
Hydrocolloids are obtained using different processes and are often additionally modified in order to specifically control their properties.
Features and functions
With hydrocolloids, for example pentosans and guar gum, the water content in the dough can be increased and the retrogradation of the starch can be disrupted.
viscosity
Due to their size and intermolecular interaction, the hydrocolloids are able to increase the viscosity of a solution, ie to reduce its “mobility”. The extent of the increase in viscosity depends essentially on the concentration and the chemical nature of the hydrocolloid.
The increase in viscosity enables the use of the hydrocolloids as thickeners , e.g. B. to be able to permanently foam pudding dishes or as a "filler" in diet products.
Gel formation
Under certain conditions, hydrocolloids form gels. Three-dimensional, disordered networks of linked hydrocolloids are created in which the solvent is enclosed. The extent of gel formation and the gel properties depend not only on the hydrocolloid and its concentration, but mostly also on temperature , pH value , foreign substances and coagulation time.
Gel formation is used in the production of puddings , jellies , gummy bears, jams and many more. utilized.
solubility
Despite their size and surface, hydrocolloids can usually be dissolved in water in large quantities. The reason for this is mainly the presence of electrical charge carriers and large hydrate shells on the hydrocolloid. These properties not only stabilize the hydrocolloid itself in aqueous solution, but also make it possible for other substances to dissolve that would otherwise fail .
This property of the hydrocolloids as a stabilizer is used in many dairy products.
use
Hydrocolloids are mainly used in food technology. They are also used in the manufacture of cosmetics or safety fuel paste for fondue burners. In medicine, hydrocolloids provide valuable services as hydrocolloidal wound dressings in wound treatment .
Hydrocolloid is also used in dentistry as an impression material , for impressions of body parts on living people, of technical objects, for death masks and in the preparation and museum areas.
In 1926 the hydrocolloid impression material “Negocoll” was first invented in Switzerland by the doctor Alfons Poller . In 1936 Alfons Schmidt developed the hydrocolloid impression compound “Formalose” in Germany .
literature
- Handbook of Hydrocolloids ; Woodhead Publishing Ltd., Abington, Cambridge 2000
- Trueb, LF: Vegetable natural products. How plant products shape our everyday life. Stuttgart, 2015. ISBN 978-3-443-01084-3