Polysaccharides rheological properties

The search for a low-cost, effective mobility control agent is currently focused on dilute aqueous solutions containing partially hydrolyzed polyacrylamides or polysaccharides. Rheological properties have been studied, including the effects of polymer concentration, shear rate, electrolyte concentration, and type of electrolyte. 

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. 

In this system, the high molecular weight polysaccharide polymer, is used to extend the rheological properties of bentonite. 

Stabilizing agents are used to maintain drilling fluid rheological properties at highly elevated downhole temperatures. Chromium and chromium-free lignosulfonates, polyglycol ethers, sodium polystyrene sulfonate-co-maleic anhydride), and a melanin polymer have been used in this application. Additives such as sodium diethyldi-thiocarbamate have been used to stabilize aqueous polysaccharides such as xanthan gum (18). 

Emphasis in the initial phase of our work was placed on sulfated polysaccharides that are antiviral. Not only were the desired rheological properties and long-term stability achieved in DCE formulations, the activity of the dextran sulfate or N9 were not compromised. DCE formulations containing DS display strong anti-HIV activity in vitro in comparison with negative (not shown) and positive controls (Figure 2). This is an important first step in the screening process towards clinical effectiveness. 

Grant, J., Cho, J., Allen, C. (2006). Self-assembly and physicochemical and rheological properties of a polysaccharide-surfactant system formed front the cationic biopolymer chitosan and nonionic sorbitan esters. Langmuir, 22,4327- 4335. 

The term food colloids can be applied to all edible multi-phase systems such as foams, gels, dispersions and emulsions. Therefore, most manufactured foodstuffs can be classified as food colloids, and some natural ones also (notably milk). One of the key features of such systems is that they require the addition of a combination of surface-active molecules and thickeners for control of their texture and shelf-life. To achieve the requirements of consumers and food technologists, various combinations of proteins and polysaccharides are routinely used. The structures formed by these biopolymers in the bulk aqueous phase and at the surface of droplets and bubbles determine the long-term stability and rheological properties of food colloids. These structures are determined by the nature of the various kinds of biopolymer-biopolymer interactions, as well as by the interactions of the biopolymers with other food ingredients such as low-molecular-weight surfactants (emulsifiers). 

Cui, W., Eskin, N. A. M., and Biliarderis, C. G. (1993). Water-soluble yellow mustard (Sinapis alba L.) polysaccharides partial characterization, molecular size distribution and rheological properties. Carbohydr. Polym. 20 215-225. 

S. Geresh, I. Adin, E. Yarmolinsky, and M. Karpasas, Characterization of the extracellular polysaccharide of Porphyridium sp. Molecular weight determination and rheological properties, Carbohydr. Polym., 50 (2002) 183-189. 

Millan, A., Nieto, M., Baudin, C. et al., Thermogelling polysaccharides for aqueous gelcasting—Part II influence of gelling additives on rheological properties and gelcasting of alumina, J. Eur. Ceram. Soc., 22, 2217, 2002. 

Rheological properties. Viscosity, an important physicochemical property of many foods, can be modified by proteins or polysaccharides. The caseins form rather viscous solutions, a reflection of their rather open structure and relatively high water-binding capacity. While the high viscosity of caseinate may be of some importance in casein-stabilized emulsions, it causes production problems for example, due to very high viscosity, not more than about 20% protein can be dissolved even at a high temperature. The low protein content of caseinate solution increases the cost of drying and results in low-density powders which are difficult to handle. 

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