Amylopectin application

The viscosity of polymer solutions has been considered theoretically by Flory,130 but although this theory has been applied to cellulose esters,131 no applications have yet been made in the case of the starch components. Theoretical predictions of the effect, on [17], of branching in a polymer molecule have been made,132 and this may be of importance with regard to the viscometric behavior of amylopectin. 

Retrogradation is another important property of starch. It is generally accepted that retrogradation is involved in the staling of baked products such as bread. In particular it appears that retrogradation is the recrystallisation of the amylopectin present. Notably, retrogradation is still a subject of research. The application of techniques such as 13C NMR allows insights that older techniques do not provide. 

This paper will also assume that the reader has basic starch and cellulose knowledge and that it is not necessary to review the structure of the molecules. It is, however, important to know that starch from native, non-genetically selected sources, is a mixture of two molecules and not simply one compound. Amylose is an essentially linear molecule and differs from amylopectin, which has about 4-6%oC-(l—>6) branches, even though both molecules are mainly o4 -(1—>4) linked D -glucose. The differences in these two molecules and their chemical modifications are the basis of application technology and the reason for the growing importance of specialty starches. 

Monosubstitution of wheat starch by acetyl or hydroxypropyl groups27 without crosslinking yields products with a reduced pasting temperature, and yields pastes with enhanced clarity and viscosity but with increased stringiness (Table 10.14). The usefulness of this product is somewhat limited and requires special applications. Amylose has been found to be hydroxypropylated —20% more than amylopectin in corn and potato starches at a molar substitution level of 0.1 (3.5% hydroxypropyl).425,426... 

Carbohydrase (Bacillus acidopullulyticus) Produced as an off white to brown, amorphous powder or a liquid by controlled fermentation using Bacillus acidopullulyticus. Soluble in water (the solution is usually light yellow to dark brown), but practically insoluble in alcohol, in chloroform, and in ether. Major active principle pullulanase. Typical applications used in the hydrolysis of amylopectins and other branched polysaccharides. 

One of the more important applications of methyl sulfoxide as a sugar solvent is for n.m.r. spectral studies, where, in conjunction with acetone-de, it has been used because exchange reactions are suppressed191 (see the n.m.r. section, p. 124). Methyl sulfoxide dissolves both amylose and amylopectin,192 and these can then be separated by the judicious use of co-solvents after dissolution.193 Ultracentri-... 

A method of determining airborne iodine has also been reported.241 Here, iodine is absorbed into 5% aqueous KI and spectrophotometrically determined at 590 nm in the form of its complex with starch. This method is selective with respect to bromine and chlorine, and the sensitivity of this method is 0.25 mg of I2 per m3 of air. The concentration of the, 31I isotope in water can be determined by a method involving isotope exchange in the starch-iodine complex.242 Flow-injection determination of ascorbic acid (0.1-40 mg/mL) has been proposed.243 Iodine is generated in the flow system as I3- ions, which are in turn exposed to starch to produce a steady signal at 350 and 580 nm. Ascorbic acid provides inversed maxima which are measured. This method is recommended for analysis of ascorbic acid in fruit juice, jam, and vitamin-C preparations. Use of the blue complex has also been reported for determination of sodium dichloro-isocyanurate in air.244 Obviously the blue reaction is applicable in the determination of amylose, amylopectin, and starch,245-252 as well as modified starches.245,253-255... 

Statches ftom different plant sources differ in their amylose/ amylopectin ratio. For example, com starch contains about 27% amylose, potato starch about 22%, and tapioca statch about 17%. In contrast, waxy com statch contains almost entirely amylopectin, with no amylose. These diffetences modify the physical properties of the statches such that the various types may not be interchangeable in a given pharmaceutical application. For example, amylose-rich maize starch has been studied as a potential tablet film-coating ingtedi-... 

Kent and coworkers briefly reported the detection, after application of zone electrophoresis in barbiturate and other buffers, of a number of neutral polysaccharides, although no details of mobilities were noted. In a borate buffer at pH 8.0, amylopectin was observed to migrate toward the cathode and to be stained red with iodine, whereas amylose is stained blue and remains stationary. 

Both waxy maize and waxy sorghum are varieties recently developed they have a high content of amylopectin and find their major application in the food industry, in competition with tapioca and potato starches. 

Erlanderi has suggested an alternative theory, which accounts for the coexistence of a granular starch and a glycogen-type polysaccharide in sweet corn, and which is also applicable to all other plants. It is postulated that glycogen is synthesized first partial debranching then occurs, to yield amylopectin and short, linear chains of (1— 4)-linked a-D-glucose... 

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