Alginic Acid
Alginic acid, being insoluble in water, cannot act as a thickener or gelling agent on its own. To dissolve it in water, an alkali must be added to neutralize it.
When alginic acid forms salts with monovalent cations like sodium (Na) or potassium (K), it becomes soluble. However, it becomes insoluble when it forms salts with polyvalent cations such as calcium (Ca) or iron (Fe).
Though alginic acid doesn’t dissolve in water naturally, special processing methods can produce a type of alginic acid that readily absorbs water and swells.
This swelling type of alginic acid increases the apparent viscosity of the solution as it absorbs water, resembling starch paste in consistency. As a result, alginic acid can be categorized into two types: swelling and non-swelling.
Alginic acid is more heat-sensitive than sodium alginate and other alginate salts, causing its molecular weight (degree of polymerization) to decrease relatively quickly. To preserve its molecular weight, it should be stored at the lowest possible temperature.
Applications
Food Applications
Alginic acid is commonly used in wheat flour products such as bread and noodles to enhance product quality. It helps retain water in dough, resulting in a softer texture in the final baked goods.
Additionally, alginic acid interacts with starch and proteins in the flour, reinforcing the dough structure during cooking or baking.
Major Applications:
- Bakery products
- Instant noodles
- Confectionery
- Frozen noodles
Pharmaceutical Applications
Alginic acid is typically insoluble in water, but it becomes soluble when treated with an alkali. In pharmaceutical formulations, certain tablets are designed to remain intact in the stomach but dissolve in the intestines for proper release of the active ingredient. To achieve this controlled release, tablets often contain alginic acid, a disintegrant that swells upon contact with water.
While ingredients like starch are frequently used to form tablets, adding alginic acid alters their properties, offering a distinct behaviour compared to starch-based tablets.
These tablets are gastro-resistant due to the fact that alginic acid does not dissolve in the acidic environment of the stomach, allowing the tablet to pass through to the intestines. As the pH gradually increases in the intestines, alginic acid starts to dissolve, causing the tablet to break apart and release the active ingredient.
Alginic acid plays a critical role in the development of tablets that are insoluble in the stomach and designed to release their contents in the intestines.
Cosmetic Applications
Alginic acid is insoluble in water but becomes soluble when neutralized with alkali. In cosmetics, it is often used for its thickening and gelling properties, enhancing the texture and consistency of various products.
Alginic acid is commonly found in products like creams, lotions, and gels, where it helps to improve spread ability and provide a smooth, luxurious feel on the skin. It also acts as a stabilizing agent, preventing separation of ingredients in emulsions and suspensions. Due to its ability to absorb water and form a gel-like consistency, it is widely used in facial masks, moisturizers, and other skin care products for hydration and a smooth texture.
Its ability to form a film on the skin also makes it useful in products that need to provide a protective barrier or enhanced moisturization.
Industrial Applications
Alginic acid is insoluble in water but can be dissolved with alkali, making it highly versatile in various industrial applications.
In the paper and textile industries, alginic acid is valued for its ability to form films and gels, which are used in coating applications to provide smooth, durable surfaces. Additionally, it is employed in the production of biodegradable materials, offering an eco-friendly alternative to traditional synthetic polymers.
Alginic acid’s ability to gel, thicken, and stabilize makes it an invaluable material across a range of industrial sectors, from food production to pharmaceuticals to textiles.