Amylopectin chemical structure

Most starches are composed of two kinds of polysaccharides, a linear o -(1 4) linked glucan, called amylose, and an o -(1 4) linked glucan with 4.2 to 5.9% a-(l 6) branch linkages, called amylopectin. See O Fig, 1 for the chemical structure of a segment of amylose and a segment of amylopectin and O Table 1 for the percent branching in amylopectin for several different starches. 

Although the essential features of the structural modifications undergone by amylose on pyrolysis are now established, full investigations of the dextrinization of the more complicated, amylopectin component have yet to be attempted. The most useful approach in this aspect of the field is to correlate the changes in such physical properties as molecular size with alterations in chemical structure. 

Figure 4.1 Chemical structures of (a) amylose, (b) amylopectin and (c) the architecture of amylopectin, according to Robin and Mercier [14],...

Use of MALDI-TOF-MS allows relatively straightforward separation and identification of oligosaccharides with DPs up to 30. This feature makes it possible to identify products from enzymatic debranching of amylopectin. Richardsson et al. employed MALDI-TOF-MS and ESI-MS for enzyme-aided structure analysis of cationic potato amylopectin. " By MALDI-TOF-MS, identification of the oligosaccharides with DP 6-20 obtained from hydrolysis with pullulanase could be performed. Use of ESI-MS", on the other hand, provided detailed information on the chemical structure of oligosaccharides with DP <5. However, the lack of suitable standards prevented quantification by MALDI-TOF-MS and ESI-MS. 

Figure 9.8. Simplified chemical structures of amylose a) and amylopectin b)...

Starch is another widely available natural polymeric biomaterial, which is generally isolated from corn, wheat, potato, tapioca, rice, etc. The major carbohydrate reserve in the plants is in the form of starch. It mainly consists of two glucosidic macromolecules 20%-30% of linear molecule amylase and 70%-80% of branched molecule amylopectin. The chemical structure of starch is given in Figure 53.2. 

Fig. 4.1 Chemical structures and physical schematic representation of a amylopectin starch, and b amylose starch...

Dextrins are produced by a severe thermohydrolytic action in conditions of low moisture (1-5%), acid pH and very specific ranges of temperature and time. Under appropriate conditions, two main chemical reactions occur the hydrolysis of the 1,4 glucosidic bond and the rearrangement (or transglucosi-dation) of the 1,4 bond to 1,3 or 1,2 or 1,6 bonds. This rearrangement produces an amylopectin-like structure that is responsible for the superior viscosity stability of dextrins compared to the thinned products. 

FIGURE 28.2 Chemical structures and compositions of (a) amylose and (b) amylopectin. 

Figure 14 Chemical structure of starch, specifically, amylose and amylopectin.

Fig. 2.34 The chemical structures of guar gum and starch components amylose and amylopectin.

Figure 4A.11 Chemical composition of amylose and amylopectin. (a) Structure of amylose (b) Structure of amylopectin. ((a) and (b), Adapted from BeMillerJN, Whistler RL. Carbohydrates. Food Chemistry. 3rd ed. New York Marcel Deker 1996. pp. 157-223)...

The starch component of the Fantesk starch-oil composite can vary in its chemi-cal/structural properties (amylose, amylopectin, waxy) as well as in the type of crop source (corn, potato, rice, etc). Likewise, the oil component of the Fantesk starch-oil composite can have a variety of chemical/structural properties, compositions, and end uses. Over the years, Fantesk starch-oil composites of various combinations of starch and oil have been prepared and investigated for a variety of food and nonfood applications, including cosmetics, pharmaceuticals, polymers, coatings, and lubricants [4, 30-33]. 

Fig. 2.9. Chemical structure of starch. Below amylopectin molecule...

Cereal starches consist of about 25% amylose and 75% amylopectin (cf. Table 4.20). The chemical structures of these polysaccharides are presented in 4.4.4.14.3 and 4.4.4.14.4. Starch granules in some cultivars, for instance waxy corns, contain only amylopectin, while some cultivars... 

Chemical Composition. Along with additives such as plasticizers and moisture content, the chemical structure of the macromolecules used as agropolymers also affects their mechanical properties. For starch, the amylopectin... 

The ratio of amylose and amylopectin varies according to starch source. Chemical structures of starch, such as molecular sizes of amylose, branch-chain lengths... 

FIGURE 3.1 Chemical structure and composition of linear amylose and branched amylopectin.85... 

---