Water-dispersible gums

Wattle gum Water-soluble or water-dispersible gum obtained from the Australian acacia tree. 

Soothing of gastrointestinal irritation—Mucilagenous types of fiber, such as the water-dispersible gums present in psyllium seed, okra, carob, and quince seed, coat and soothe irritated areas, particularly mucous surfaces. 

The in situ process is simpler because it requires less material handling (35) however, this process has been used only for resole resins. When phenol is used, the reaction system is initially one-phase alkylated phenols and bisphenol A present special problems. As the reaction with formaldehyde progresses at 80—100°C, the resin becomes water-insoluble and phase separation takes place. Catalysts such as hexa produce an early phase separation, whereas NaOH-based resins retain water solubiUty to a higher molecular weight. If the reaction medium contains a protective coUoid at phase separation, a resin-in-water dispersion forms. Alternatively, the protective coUoid can be added later in the reaction sequence, in which case the reaction mass may temporarily be a water-in-resin dispersion. The protective coUoid serves to assist particle formation and stabUizes the final particles against coalescence. Some examples of protective coUoids are poly(vinyl alcohol), gum arabic, and hydroxyethjlceUulose. 

Starches. Starch (qv) granules must be cooked before they wiU release their water-soluble molecules. It is common to speak of solutions of polysaccharides, but in general, they do not form tme solutions because of their molecular sizes and intermolecular interactions rather they form molecular dispersions. The general rheological properties of polysaccharides like the starch polysaccharides are described below under the discussion of polysaccharides as water-soluble gums. Starch use permeates the entire economy because it (com starch in particular) is abundantly available and inexpensive. Another key factor to its widespread use is the fact that it occurs in the form of granules. 

Locust bean gum also has excellent water-holding properties. It is cold water-dispersible, but complete hydration is accomplished only after pasteurization. This precludes its use in HTST systems. As with CMC, it causes mix separation which may be eliminated by its use with Irish moss extract. 

Natural gums Sodium alginate Anionic 1-5 Water-dispersible 4-10 or 4-11.5 Pseudoplastic Incompatible with heavy-metal ions and sensitive to acids and ethanol in greater than 5%... 

Any hydrophilic plant material, or derivative, that forms a viscous dispersion or solution with water. Example gum arabic (acacia gum) is derived from Acacia trees and is used in paints, inks, adhesives, and textiles. 

The classical thermodynamic and kinetic model is that of a rigid sphere impenetrable by water. A spherical geometry has been observed in many polysaccharide systems, notably hyaluronic acid-protein complexes (Ogston and Stainer, 1951), dispersed gum arabic (Whistler, 1993), and spray-dried ungelatinized starch granules (Zhao and Whistler, 1994). Spherulites of short-chain amylose were obtained by precipitation with 30% water-ethanol (Ring et al., 1987), and spherulites of synthetic polymers were obtained... 

Figure 4-42 Values of Yield Stress of Starch-Xanthan Dispersions Relative to those of the Starch-Water Dispersions (YSA SO) and Relative Mean Granule Diameters (D/DO) Plotted against Values of c[j) of Xanthan Gum waxy maize (WXM), cross-linked waxy maize (CWM), and cold water swelling (CWS).

Achayuthakan et al. (2006) studied vane yield stress of Xanthan gum-stareh dispersions. The intrinsic viscosity of Xanthan gum was determined to be 112.3 dl/g in distilled water at 25°C. In addition, the size of the granules in the dispersions of the studied starches waxy maize (WXM), cross-linked waxy maize (CWM), and cold water swelling (CWS) were determined. The values of yield stress of the starch-xanthan dispersions relative to those of the starch-water dispersions (YSA"S0) and relative mean granule diameters (D/DO) plotted against values of c[ ] of xanthan gum are shown in Figure 4-42. With the values of YS/YSO being less than 1.0, there was no synergism between CLWM starch and xanthan gum. 

Solubility practically insoluble in organic solvents. In cold or hot water, guar gum disperses and swells almost immediately to form a highly viscous, thixotropic sol. The optimum rate of hydration occurs at pH 7.5-9.0. Finely milled powders swell more rapidly and are more difficult to disperse. Two to four hours in water at room temperature are required to develop maximum viscosity. 

Microcrystalline cellulose is water dispersible and has properties similar to water soluble gums. Microcrystalline cellulose is used as a bulking agent, as a fat replacer in emulsion based food products, and is used to add creaminess to drinks, e.g. chocolate drinks. Decreasing particle size of microcrystalline cellulose increases its water retention capacity. 

Next, with another of his students, he turned to editing the book Industrial Gums. Now in its third edition, Industrial Gums is a praetieal book that deseribes the chemistry, properties, and applications of water-soluble or water-dispersible polysaccharides and polysaccharide derivatives with commereial value or potential. In the introductory chapter of this book, Professor Whistler presented important concepts about the relationships of structure to properties of polysaeeharides, an area he championed after it had been introduced by D. A. Rees. 

Among water-soluble or water-dispersible binders are dextrins, gum arabic, casein, and animal hide glue. The latter has received great attention from the match manufacturers as well as from other industries. Hide glue is marketed in a great variety of viscosi-... 

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