Cereal Chem. 71:263-268   |  VIEW ARTICLE


Structure and Properties of Amylose, Amylopectin, and Intermediate Materials of Oat Starches.

L. Z. Wang and P. J. White. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

Starches isolated from three types of oats (Avena sativa L.) with a range of lipid contents (6.2, 8.0, and 11.2%) were fractionated into amylose (AM), amylopectin (AP), and intermediate materials (IM) by using 1-butanol precipitation. The structures and physicochemical properties of AM, AP, and IM were characterized by using iodine affinity (IA), blue value, maximum absorbance wavelength, limiting viscosity number, and high-performance size-exclusion chromatography before and after debranching with isoamylase for AM and after debranching for AP and IM. The IA values of AM were 18.4-18.9 g/100 g. The weight-average degree of polymerization (DPw) and apparent DPw distribution of AM ranged from 939 to 1,208 and from 392 to 2,920 glucose units, respectively. These values tended to be smaller than those of corn (Zea mays L.) and rice (Oryza sativa L.) starches reported in literature. The AP had IA values ranging from 0.30 to 0.58 g/100 g. The chain lengths of AP ranged from 204 to 181, 32 to 31, and 20 to 17, by weight of glucose units, for high, intermediate, and low molecular weight fractions, respectively. The chain lengths and chain-length distribution of AP showed differences among oat starch types, with a decreased degree of multiple branching of AP accompanying increased starch-lipid and amylose contents. All structures and properties of IM suggested that the IM contained less highly branched molecules than did AP.