Thickener , hydrocolloid

These are formulated as O/W or W/O emulsions with special surfactant systems and/or thickeners to give a viscosity profile similar to that of lotions, but with orders of magnitude greater viscosities. The viscosity at low shear rates (< 0.1 s ) can reach thousands of Pa s and they retain a relatively high viscosity at high shear rates (of the order of few hundred Pa s at shear rates > 1 s ). These systems are sometimes said to have a body , mostly in the form of a gel-network structure that may be achieved by the use of surfactant mixtures to form liquid crystalline structures. In some case, thickeners (hydrocolloids) are added to enhance the gel-network structure. 

Sodium alginate (algin) is one of the most widely used hydrocolloids for ice cream. It is supplied in several viscosity types. The lower viscosity material is recommended in order to prevent thick mixes. It is used at a level of 0.15 to 0.25%. It is added to mix at higher temperatures in order to minimize precipitation by calcium salts present in milk products. Sodium alginate is sensitive to high acidities often developed in some mixes and causes thickening. 

For a colloidal system containing a mixture of different biopolymers, in particular a protein-stabilized emulsion containing a hydrocolloid thickening agent, it is evident that the presence of thermodynamically unfavourable interactions (A u > 0) between the biopolymers, which increases their chemical potentials (thermodynamic activity) in the bulk aqueous phase, has important consequences also for colloidal structure and stability (Antipova and Semenova, 1997 Antipova et al., 1997 Dickinson and Semenova, 1992 Dickinson et al., 1998 Pavlovskaya et al., 1993 Tsap-kina et al., 1992 Semenova et al., 1999a Makri et al., 2005 Vega et al., 2005 Semenova, 2007). 

The addition of hydrocolloids (e.g. carrageenans, pectins or car-boxymethyl cellulose) as thickening agents will greatly increase the apparent viscosity of the product. The production of extracellular polysaccharides by certain bacteria will also increase the viscosity of milk products. 

Stabilizers and Thickeners. Many food products receive their textural properties from a group of compounds known as hydrocolloids. Hydrocolloids fall into Iwo classes polysaccharides and proteins. They include loeust bean gum. guar gum, gum arabic. carrageenan, xanthan gum. cellulose. agar, starch, pectin, alginates, and gelatin. See also Stablizer. 

Baines, Z. V. and Morris, E. R. 1987. Flavour/taste perception in thickened systems the effect of guar gum above and below c. Food Hydrocolloids 1 197-205. 

Xanthan gum is also used as a hydrocolloid in the food industry, and in cosmetics it has been used as a thickening agent in shampoo. 

The main factors to bind liquids and/or to influence the consistency of the dough are wheat glutens, pentosanes and mechanically damaged starch (through the grinding process of the com) or hydrocolloids (for example thickeners). 

Gelatin is a multifunctional ingredient used in foods, pharmaceuticals, cosmetics, and photographic films as a gelling agent, stabilizer, thickener, emulsifier, and film former. As a thermoreversible hydrocolloid with a narrower gap between its melting and gelling temperatures, both of which are below human body temperature. 

Frigesa . [GrOnau] Hydrocolloids thickener and stabilizer for desserts, ice cream, dressings. 

Gum Arabic acts as protective colloid and excellent emulsifier and the molecular aggregation can cause both shear thinning and time-dependent thickening behavior at low shear" Gum Arabic has the ability to create a strong protective film around oil droplets" and is compatible with the most other plant hydrocolloids, proteins, carbohydrates, and modified starches. The viscosity of a solution of a mixture of gum arabic and gum tragacanth tends to be lower than that of either constituent solution. 

---