You may have come across many food additives, out of which you sometimes are not aware of. Mostly the foods we buy consist of some kind of preservatives or additives to make them usable for a long time. One of the most popular food additives is Carrageenan, which is found in a variety of food products that you use in your day to day life.
The viscosity of all carrageenan solutions is evaluated under certain conditions where there is no susceptibility for the solution to begin gelling. In case of a hot (carrageenan) solution is allowed to cool, the viscosity increases slowly until the right gelling temperature is attained. As the gel begins to shape, the viscosity increases substantially and therefore in case of carrageenan solutions, the viscosity should be measured at high temperatures like 75 degrees Celsius to prevent the gelation effect.
Commercial carrageenans are normally available in some specific viscosities which range between 5-800 cps. The viscosity depends on temperature, concentration, existence of other solutes and the kind of carrageenan with its molecular weight. In case of a higher molecular weight the viscosity tends to change rapidly or higher concentration in solutions. Viscosity decreases with the rise in temperature and vice versa.
Carrageenan solutions are stable at alkaline pHs or neutral pHs. At all lower pHs the stability decreases like at high temperatures. With decrease in pH, hydrolysis of the polymer takes place, ending up in with a loss of gelling capacity and viscosity.
That is why, upon the formation of the gel, even when the pHs is low, hydrolysis will not take place and the gel will remain stable. If you are using it for practical applications, make sure you know the carrageenan limitations under particular acid conditions. So, avoid processing solutions with carrageenan at high temperatures and at low pHs.