Gelling Agents

Functional Biopolymer Particles: Design, Fabrication, and Applications

“…Biopolymer particles can be formed by disrupting a macroscopic gel, or by promoting biopolymer association at a concentration below the level required for macroscopic gel formation. The interactions that form gel networks can be grouped into 2 main categories: physical and chemical (Totosaus and others 2002; Williams 2007). Physical gels are typically held together by hydrogen bonding, hydrophobic, and divalent ion cross‐linking (see below), while chemical gels are covalently bonded via inherent (for example, disulfides) or added substances (see below).…”

“…The ability of polysaccharides to self‐associate and form gels has important implications for biopolymer particle formation. In an excellent review by Williams (2007), gelling biopolymers are categorized by their gel formation mechanism: cooling (for example, carrageenan); heating (methyl cellulose); ion addition (alginate); and retrogradation (amylopectin). Physical interactions in polysaccharides are largely based on hydrogen bonding and, among ionic species, electrostatic interactions (often via divalent ions).…”

“…The addition of oppositely charged ions to the system can promote biopolymer association by screening the electrostatic interactions, or by acting as a salt bridge. For example, calcium ions (Ca 2+ ) are frequently used to cross‐link anionic polysaccharides such as pectins, alginates, or carrageenans (Williams 2007). Potassium ions (K + ) are used to cross‐link anionic carrageenans through the formation of an “egg‐box” structure (Williams 2007).…”

“…For example, calcium ions (Ca 2+ ) are frequently used to cross‐link anionic polysaccharides such as pectins, alginates, or carrageenans (Williams 2007). Potassium ions (K + ) are used to cross‐link anionic carrageenans through the formation of an “egg‐box” structure (Williams 2007). Mineral ion addition may be used to cross‐link biopolymer particles in various ways (Burey and others 2008).…”

Structured biopolymer-based delivery systems for encapsulation, protection, and release of lipophilic compounds

“…The cross-links formed may be either chemical or physical in nature, which often plays an important role in determining the reversibility of the system. Chemical cross-linking involves the formation of covalent bonds between polymers, while physical cross-linking involves the formation of non-covalent bonds, such as hydrogen bonding, hydrophobic association, and ion bridging (Williams, 2007). Both proteins and polysaccharides are capable of gelation although the gelation mechanism and properties of these two types of gels are often quite different (Renard, van de Velde, & Visschers, 2006).…”