Structure of the amylopectin fraction of amylomaize

✍ Scribed by Chieno Takeda; Yasuhito Takeda; Susumu Hizukuri

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 589 KB
• Volume: 246
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(93)84039-9

✦ Synopsis

The amylopectin fraction (Ap-fraction) from three amylomaize starches (amylose content, 36, 41, and 59%) was fractionated into three amylopectin components (having different molecular size) and a short-chain component by gel-permeation chromatography. The content of the largest amylopectin component was relatively low in a high-amylose maize starch and it had an iodine affinity (i.a., g/100 g) of 1.94-2.50 and average chain length @I of 29-30. Both values increased with decrease of molecular size (La. < 7.23, a < 41). The proportion of long side chains [weight-average dp cair,) 99-1101 increased with decrease of molecular size, whereas that of short side chains t&,, 17-22) decreased. This is the reason why a smaller component had a larger i.a. and a. Very long @&, 400-690) and medium-size (d& 45-48) side chains were present in similar proportions, regardless of molecular size. The short-chain component was slightly branched (number of chains, 1.9-2.1 on average) and had an i.a. of 8.20-9.57, d& of 120, and number-average dp of 92-95. A large amount of the short-chain component (27% of the Ap-fraction, by weight) was found in the high-amylose (59%) maize starch.