Amylopectin chain length distribution

Table 10.8 Chain-length distributions of amylopectins determined after debranching3...

The A plus Bj chains dominate the chain length distributions in amylopectins both by weight (58-74%) and by number (85-93%), compared with the sum of the long B chains (see Table 10.8). The A and Bj chains are believed to occur within one cluster, while the B2 and B3 chains transverse two and three clusters, respectively. The B4 chains and beyond are small in number and were not detected by the end group labeling protocol. However, the weight-percent of B4 chains with DPn above —50 (DPW —80) is measurable.217,224,225... 

Table 12.6 Chain length distribution of components from amylopectin debranching33...

There were differences between oat varieties in chain lengths and chain length distributions of amylopectin. The degree of multiple branching decreased when the starch-lipid and amylose contents increased.31 The intrinsic viscosity of amylopectin has also been determined (Table 15.2). In another investigation, values ranging from 170 to 207 mL/g were reported.7... 

Figure 3.246 Chain length distributions of amylopectins of different origin after depolymerization. Separator column Carbo-Pac PA1 eluent (A) 0.15 mol/L NaOH, (B)...

The major constituent of starch, amylopectin, can also be analyzed after depolymerization [186]. As can be seen from the chromatogram in Fig. 3-187, information on the chain length distribution of amylopectin derived from rice, for example, can be obtained in less than 40 minutes. 

Several models have been proposed for amylopectin structure (2), but cxily the cluster models (3 4) have been accepted widely. The cluster model shown in Figure 1 has been presented based on the chain-length distributions of some amylopectins (5.). The chains are named as A, B, and C by Peat et al. ( ) that is, A chains link to... 

Silverio J, Fredriksson H, Andersson R, Ehasson AC, Aman P. The effect of temperature cycling on the amylopectin retrogradation of starches with different amylopectin unit-chain length distribution. Carbohydr Polym 2000 42 175-184. 

FIGURE 5.1 Cluster model of amylopectin. A and B denote nomenclature of branch chains, 0=reducing end, c.l. = chain length in degree of polymerization. Reprinted from Carbohydrate Research, Vol. 147, Hizukuri (1986), Polymodal distribution of the chain lengths of amylopectin, and its significance, Pages 342-347, with permission from Elsevier. 

Hizukuri, S. (1986). Polymodal distribution of the chain lengths of amylopectin, and its significance. Carbohydr. Res. 147,342-347. 

Hizukuri, S. (1985). Relationship between the distribution of the chain length of amylopectin and the crystalline structure of starch granules. Carbohydr. Res., 141,295-306. 

Most potato starches are composed of a mixture of two polysaccharides, a linear fraction, amylose, and a highly branched fraction, amylopectin. The content of amylose is between 15 and 25% for most starches. The ratio of amylose to amylopectin varies from one starch to another. The two polysaccharides are homoglucans with only two types of chain linkage, a-(l 4) in the main chain and a-(l 6)-linked branch chains. Physicochemical properties of potato and its starch are believed to be influenced by amylose and amylopectin content, molecular weight, and molecular weight distribution, chain length and its distribution, and phosphorus content (Jane and Chen, 1992). 

The average branch chain length of amylopectin has a bimodal distribution that differs from the single modal distribution of that of glycogen.257 The average branch chain... 

DISTRIBUTION OF CHAIN LENGTHS OF AMYLOPECTINS FROM DIFFERENT SOURCES"... 

---