Sodium alginate is soluble in both cold and hot water and it produces a colloidal solution. The viscosity of this solution is measured by a viscometer.
Viscosity is affected by the molecular weight of the sodium alginate polymer. Viscosity changes are dependent on the degree of polymerization of the uronic acid units, the molecules which comprise alginic acid. When the molecular weight is high, the viscosity is high even at low concentrations. The viscosity decreases as the molecular weight decreases.
Aqueous sodium alginate solution exhibits smooth flow properties; the closest to Newtonian behavior amongst the natural hydrocolloids.
These flow properties can also be adjusted to thixotropic behavior by the addition of a small amount of calcium salt.
Sodium alginate is used as a thickener in various foods by combining these behaviors.
When contacting a calcium salt with a sodium alginate solution, it forms a gel instantly. By utilizing this function, jelly molded into spherical or spindle-shapes can be created and these are used to make imitation foods such as salmon roe or shark fin.
Calcium ions can be chelated with phosphates to delay the reaction with sodium alginate or, conversely, acid can be used to accelerate the reaction by promoting the ionization of calcium ions.
By adjusting the ionization of calcium in this way, the reaction time and the shape of the solid can be freely designed.
Gels made by reacting sodium alginate with calcium salts are heat stable and, unlike other gelling agents such as gelatin, carrageenan, and agar, do not dissolve when heated (heat irreversible).
This is a unique property of sodium alginate compared with other natural hydrocolloids.
Since many processed foods are heated for cooking and sterilization purposes, the shape of food can be difficult to maintain using gelling agents that are vulnerable to heat.
Heat resistance is achieved by using a gel of sodium alginate and a calcium salt or adding these to other gelling agents.
- Before heating
- After heating
By combining the thickening and gelling functions, sodium alginate is used as a stabilizer to maintain the physical properties of foods and increase the commercial value.
One of the most popular applications is the stabilizing of ice cream. When frozen, ice cream contains a lot of fine bubbles. By adding sodium alginate, it improves overrun and gives a smooth and soft mouthfeel.
Sodium alginate reacts with calcium in milk to form a loose gel network in ice cream.
As a result, ice cream containing sodium alginate has increased heat shock resistance, making it a stable product which is not altered during storage and distribution.
- Ice cream
- Bakery filling
- Food binding (Onion ring, Olive pimento)
- Imitation food (Artificial salmon roe, Artificial shark fin)
- Heat resistance
Alginic acid and its salts are evaluated by JECFA, and ADI (Acceptable Daily Intake) is not specified*.
As sodium alginate is derived from natural seaweed, our products are safe to use and BSE-free, GMO-free and pesticide-residues-free.
*Alginic acid and its salts are regarded as safe materials and they are evaluated as alginic acid in “Group ADI”.
Sodium alginate is extracted and clarified from natural seaweed. In the industrial area, the major application is textile printing.
The viscosity of the aqueous sodium alginate solution assists the dye penetration of the fabric resulting in a uniform, precise and controllable dyeing process.
Sodium alginate, which is soluble in cold water, has an excellent position in the textile printing field because it has good desizing after dyeing, and its high biodegradability reduces the load on wastewater treatment systems.
Also, sodium alginate is used in a wide range of fields, such as paper sizing agents, binders for welding rods, and gelling agents for pet foods.
Fine Chemical Applications
Highly purified sodium alginate is used for fine chemical applications such as pharmaceuticals and cosmetics. Research using sodium alginate is being conducted in regenerative medicinal fields and many interesting research results are being released.
Functional Material Applications
Sodium alginate is natural dietary fiber. Appropriate intake of sodium alginate improves bowel movements.
Low molecular weight sodium alginate has also been used as a food for specific health uses, such as the effective excretion of cholesterol from the body.
Grades of KIMICA’s sodium alginate product are classified by the viscosity of a 1% solution.
Ultra low viscosity products (ULV series) are classified by a 10% solution viscosity.
In addition to viscosity, they are also classified according to gel strength (M/G ratio), purity, quality control specifications, etc.
As we have a range of products, the choice of a suitable grade depends on the application.
For more information, please contact us.