Polydextrose Solution

Polydextrose was the first of the new generation , healthier speciality carbohydrates to be used in soft drinks. In the 1980s, Otsuka in Japan launched Fibermini, which was in effect a flavoured polydextrose solution aimed at the health drink market as a fibre supplement. 

Polydextrose Solution occurs as a clear, straw-colored liquid. It is a 70% to 80% water solution of polydextrose. 

In tableting, polydextrose solutions are used as binders in wet-granulation processes. Polydextrose is also used in the manufacture of directly compressible tableting excipients. Polydextrose solutions may also be used, in conjunction with other materials, as a film and tablet coating agent. 

Viscosity (dynamic) polydextrose solutions behave as Newtonian fluids. Polydextrose has a higher viscosity than sucrose or sorbitol at equivalent temperatures. This characteristic enables polydextrose to provide the desirable mouthfeel and textural qualities that are important when formulating syrups and viscous solutions. See Figure 2. 

Figure 2 Viscosity of polydextrose solutions at 25°C at various concentrations.

Polydextrose was developed by Pfizer and is now marketed by Danisco under the Litesse brand. Polydextrose is produced from glucose, sorbitol and citric acid and, under tightly controlled processing conditions, a randomised glucose polymer is produced. It is soluble in water, neutral in taste and is available in liquid (70% solution) or dry format, as an amorphous powder or agglomerated granule. It is extremely stable to extremes of pH and temperature. 

Polydextrose (Appi, 1991) is a synthetic, randomly bonded, amorphous, condensation heterooligomer of glucose, sorbitol, and citric acid, with M not exceeding 5000 Da and a solution pH of 2.5-3.5. Its solution viscosity is slightly higher than that of sucrose at similar concentrations, and it forms a clear melt above 130°C. 

Anhydro-D-glucose, Glucose and Sorbitol Transfer 30 mg of sample, accurately weighed, into a screw-cap vial, and add about 2 mL of pyridine. While flushing the vial with a stream of dry air or nitrogen, heat at 80° to 90° until the solution volume is reduced to 0.2 to 0.5 mL. Add a second portion of pyridine, and repeat the evaporation procedure. Continue as directed in the monograph for Polydextrose. Nickel Determine as directed under Nickel Limit Test, Appendix IIIB. 

These are both commercially available in forms suitable for direct compression with good flow and binding properties. The former is a water-granulated product of microcrystalline aggregates.A similar form of xylitol is available, and in the case of xylitol, there are also products pregranulated with either polydextrose or carboxymethyl cellulose. Both substances are highly soluble in water with negative heats of solution. 

Solubility completely miscible in water. Sparingly soluble to insoluble in most organic solvents. Polydextrose has a higher water solubility than most carbohydrates and polyols, allowing the preparation of 80% w/v solutions at 20°C. Polydextrose is soluble in ethanol and only partially soluble in glycerin and propylene glycol. 

Polydextrose may be partially reduced by transition-metal catalytic hydrogenation in aqueous solution. It may be neutralized with any food-grade base and/or decolorized and deionized for further purification. 

Many other suggestions have been made regarding the intermediate steps in the conversion of dextrose into alcohol and carbon-dioxide and the nature of the intermediate products. Buchner and Meisenheimer, B. (1905), 38 620, suggested that lactic acid is the first product of the action of zymase on dextrose since it is known that this acid is formed in muscle tissue by the oxidation of glycogen, which is a polydextrose. They added to this theory the assumption of a second enzyme, lactacidase, which carries on the decomposition of the lactic acid into ethyl alcohol and carbon dioxide cf. Bio. Z. (1922), 128 144 and 132 165. This suggestion was based on the observation that a concentrated solution of dextrose when treated with alkali yields about 3% of alcohol on exposure to sunlight. Under similar conditions a more dilute solution gives a 50% yield of lactic acid. 

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