Hydrocolloid

Hydrocolloids are a group of hydrophilic polymers that readily interact with water to form viscous solutions or gels. They are typically high molecular weight substances, including polysaccharides and some proteins, which, at sufficient concentration or with appropriate environmental conditions, develop a three-dimensional network that entraps water. Hydrocolloids are used to modify texture, viscosity, and stability in various products and processes.

Common natural hydrocolloids include agar, alginates (from brown seaweed), carrageenan, gelatin, pectin, xanthan gum, guar gum, and locust bean gum. Their gelling and thickening behavior depends on source, structure, concentration, temperature, pH, and the presence of ions such as calcium or potassium. They can form gels, thickened solutions, or emulsions.

Properties such as viscosity, gel strength, and temperature or ion sensitivity determine their industrial applications. Some, like gelatin, gel upon cooling; others, such as alginates, form gels in the presence of divalent cations. Many hydrocolloids exhibit shear-thinning behavior that aids processing and mouthfeel in foods.

Applications span food, cosmetics, and pharmaceuticals. In food, hydrocolloids function as thickeners, stabilizers, texturizers, and to control ice crystallization or phase separation. In medicines and cosmetics, they serve as excipients, suspending agents, or thickening agents. Hydrocolloid dressings are used in wound care to form protective gels in contact with wound exudate.

Regulatory status varies by jurisdiction. Most hydrocolloids used in foods and medicines are considered safe and are listed as approved additives (for example, many carry E numbers in the European Union). Some concerns have been raised about specific hydrocolloids, such as carrageenan, leading to ongoing evaluation and labeling requirements.