Maltodextrins, linear

Enzymatic preparation of radiolabeled linear maltodextrins and cyclodextrins 43... 

The first exaiqple is based on a survey of numerous crystal structures that contain different linear maltodextrins (20-26). 

Cyclodextrin glycosyltransferase catalyzes the breakdown of starch and linear maltodextrin substrates to produce CDs, while a-amylase converts starch into linear oligosaccharides, resulting in a rapid decrease in viscosity [37]. 

Optical rotation and refractometric detectors were combined to characterize a series of dextrins by gel permeation chromatography and high performance liquid chromatography (HPLC). Gel permeation fractionates according to the hydrodynamic volume when adsorption is avoided/ and for this reason separates isomaltodextrins from linear maltodextrins. Specific rotation power [a] is directly obtained and confirms the chemical structure. Elution of cyclodextrins is also tested and discussed. HPLC reverse phase chromatography separates the anomers as shown by optical rotation and allows good resolution in the range of low DP. 

Maltodextrins may be manufactured either by acid or by acid-enzyme processes. Maltodextrins produced by acid conversion of starch from dent com contain a high percentage of linear fragments, which may slowly reassociate into insoluble compounds causing haze in certain applications. 

It is the amylose component of starch that gives the blue color when KI/I2 solution is added. To study the iodine-iodide color of amyloses of different d.p. values, maltodextrin-amylose molecules, with various avg. d.p. values from 6 to 568 were prepared by Bailey and Whelan [62], using phosphorylase, a-D-glucopyranosyl-1-phosphate, and maltohexaose. The colors of the various sized maltodextrins (1 mg) were observed when 10 1 (w/w) KI/I2 solution was added. The first color to be observed was faint red for avg. d.p. 12 a red-purple color was observed for avg. d.p. 31 a purple color was observed for avg. d.p. 40 and a blue color was observed for avg. d.p. 45. The increase in the blue value was linear as a function of avg. d.p. up to avg. d.p. 60 the absorbance at 645 nm then slowly increased and reached a maximum at avg. d.p. of 400. The intensity of the iodine/iodide color in the low molecular weight range was dependent on the concentration of the iodine. When the concentration of the iodine was increased 10-fold, the intensity was increased 50% [62]. 

Starch-Modifying Enzymes Starch is one of the most abundant carbohydrates in terrestrial plants and the most important polysaccharide used by humankind. This polymer is normally processed and used in a variety of products such as starch hydrolysates, starch or maltodextrin derivatives, fructose, glucose syrups, and cyclodextrins [148, 149]. In addition, starch is widely used as a raw material in the paper industry, in polyol production, and as economic substrate for many microbial fermentations [149]. Starch consists of a large number of glucose units that can be linearly attached as hehcal amylose [ 99% a-(l-4) and 1% a-(l-6) bonds] or branched as amylopectin [ 95% a-(l-4) and 5% a-(l-6) bonds] [69]. In nature, four types of starch-converting enzymes exist (i) endoamylases (ii) exoamylases (iii) debranching enzymes and (iv) transferases. 

As usual, a linear dependency is obtained for log plotted as a function of the degree of polymerization (DP). Universal calibration for the oligosaccharides was established (Figure 3) for the maltodextrins by plotting log [i ] M against Kd (3). ... 

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