Unit and internal chain profile of African rice (Oryza glaberrima) amylopectin

High-performance anion-exchange chromatography was used to study the unit chain profiles of amylopectins and their phi,beta-limit dextrins from two African rice (Oryza glaberrima) accessions-TOG 12440 and IRGC 103759. The samples were compared with two Asian rice (Oryza sativa) samples (cv Koshihikari and cv WITA 4) and one O. sativa x O. glaberrima cross (NERICA 4). The ratio of short:long chains ranged between 12.1 and 13.8, and the ratio of A:B-chains was similar to 1.0 in all samples. A significant difference was observed in the distribution of internal chains with regards to the proportion of short fingerprint B-chains (B-fp-chains), which in the phi,beta-limit dextrins have a degree of polymerization (DP) 3-7. The African rice starches and NERICA 4 had higher levels of B-fp-chains, but the major group of short B-chains (DP 8-25) was similar to that of the Asian rice samples. The average chain length (CL), internal chain length (ICL), and total internal chain length (TICL) were similar in all samples. However, the external chain length (ECL) was longer in the African rice samples and NERICA 4. ECL correlated positively and significantly (p <0.05) with gelatinization transition temperatures and enthalpy suggesting differences between the two rice types in cooking properties. (C) 2015 Elsevier Ltd. All rights reserved.