Amylopectin polymeric structure

Figure 2. Schematic of amylose and amylopectin polymeric structure before and after degradation by bacteria or enzymes...

Potato starch exhibits different granular stmcture and composition, as opposed to cereal starches, which are responsible for the variation in functional behavior of these starches. Cereal starches exhibit the t5 ical A type X-ray crystalline pattern, whereas potato starch shows the B-form, andlegumesthe mixed state pattern C . The A, B, and C patterns are the different polymeric forms of starch that differ in the packing of amylopectin double helices. The structure of potato starch is discussed in more detail in Chapter 4. 

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. 

Chemically, starch is a combination of two polymeric polysaccharides called amylose and amylopectin in which glucose monomers are joined to one another head-to-tail by a- 1 4) linkages. Linearly combined units constitute amylose, while branched imits constitute the amylopectin (see Figure 10.7). Structurally, the starch forms clusters of linked linear polymers, where the o -(1 4) linked chains form columns of glucose units which branch regularly at the a-(1 6) links (Figure 10.7). 

---