Amphiphilic compounds (surfactants and emulsifiers) promote the formation of emulsions by lowering the interfacial free energy (surface tension y) between the two phases, thus facilitating the subdivision of the internal phase into droplets of smaller diameter. They may be nonionic (monoglyceride), anionic (sodium lauryl sulfate), amphoteric (phosphatidyl choline), or cationic (cetyltrimethyl-ammonium bromide); cationic surfactants are not used as food additives.

Emulsifiers stabilize emulsions by preventing the contact between the droplets that would lead to coalescence. This may occur by three mechanisms: (2) establishing electrostatic charges on the droplet surfaces, (2) generating a layer of bound water (in oil-in-water emulsions) around the surface of the droplet, and (3) forming a solid film at the interface.

Materials that stabilize foams usually perform both functions. They lower the surface tension between the liquid and air phases and also stabilize the thin liquid film between the occluded air bubbles. For food purposes, effective foaming agents are usually proteins (egg white and gelatin), but certain whipping agents can enhance this functionality.

Compounds that act as thickeners or bodying agents function in one of two ways. They may increase the viscosity of the aqueous phase, or they may form a gel network within that phase. Viscosity builders are usually gums or modified starches, while gelling agents can be gums, modified starches, or proteins. Some solid materials (eg, micro-crystalline cellulose) increase the viscosity in a formulated product by adsorbing water and thus increasing the ratio of internal phase (solids, oil) to external phase (mobile water).

Nutrition Essentials

Nutrition Essentials

Get All The Support And Guidance You Need To Be A Success At Understanding Nutrition. This Book Is One Of The Most Valuable Resources In The World When It Comes To Exploring The Correct Way To Eat For Weight Loss And Maintenance.

Get My Free Ebook

Post a comment