Alginate in the seaweed forms sea minerals and salts, filling the intercellular spaces in a gentle jelly-like state. Accounting for 30-60% of the dried seaweed, alginate can be described as a natural dietary fiber and be referred to as the "primary component of seaweed."
Sodium alginate, the neutral salt form of alginic acid, is created when sodium ions bind to the carboxyl groups of the alginate polymer. While alginic acid itself is water-insoluble, sodium alginate readily dissolves in both cold and hot water, forming a homogeneous viscous solution.
A key functional characteristic is its rapid gelation upon contact with calcium ions. This ionic cross-linking occurs instantaneously, with the gel formation rate being precisely controllable through calcium ion concentration regulation.
These distinctive physicochemical properties - water solubility, controlled gelation, and viscosity enhancement - make sodium alginate a valuable functional additive. It serves as an effective thickener, controllable gelling agent, and stabilizer across diverse industrial applications.
Sodium alginate is soluble in water but it becomes insoluble at low pH or at high concentrations of calcium as alginic acid or calcium alginate are formed.
Many foods are low in pH, such as fruit drinks, dressings, fermented foods, and calcium rich dairy products. Sodium alginate cannot be used successfully to thicken or stabilize these foods.
Propylene Glycol Alginate (PGA), it is made by esterification of the carboxyl groups in alginic acid. It is soluble in both cold and hot water and forms smooth and viscous solutions. It can be used in areas where sodium alginate does not work.
PGA becomes an acidic aqueous solution when dissolved in water. It can be dissolved even in acidic foods, resulting in thickening and stabilizing effects.It does not gel with polyvalent cations and remains stable within a pH range of 3–5. This makes it suitable as a thickener and stabilizer in foods containing calcium or acidic ingredients.
Key Applications of PGA:
Salad Dressings – PGA acts as an emulsion stabilizer, often combined with xanthan gum to enhance texture and consistency.
Acidified Milk Beverages – It functions as a dispersion stabilizer, preventing protein precipitation and maintaining a smooth texture.
Beer Foam Stabilization – A small amount of PGA added to fermented beer helps create and maintain a fine, stable foam when poured.
Bread & Noodles – PGA improves dough texture, leading to increased volume and enhanced elasticity in baked goods.
