title: Unit and internal chain profile of African rice (Oryza glaberrima) amylopectin.
abstract: High-performance anion-exchange chromatography was used to study the unit chain profiles of amylopectins and their φ,β-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 × 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 ∼ 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 (Bfp-chains), which in the φ,β-limit dextrins have a degree of polymerization (DP) 3-7. The African rice starches and NERICA 4 had higher levels of Bfp-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.
authors.affiliation: Department of Food Science, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1. Electronic address: jgayin@uoguelph.ca.
authors.forename: Joseph
authors.initials: J
authors.lastname: Gayin
authors.affiliation: Guelph Food Research Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON, Canada N1G 5C9. Electronic address: elsayed.abdelaal@agr.gc.ca.
authors.forename: El-Sayed M
authors.initials: EM
authors.lastname: Abdel-Aal
authors.affiliation: Grain Quality Laboratory, Africa Rice Center, 01 B.P. 2031, Cotonou, Benin. Electronic address: J.Manful@cgiar.org.
authors.forename: John
authors.initials: J
authors.lastname: Manful
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave, St Paul, MN 55108, USA. Electronic address: eric.bertoft@abo.fi.
authors.forename: Eric
authors.initials: E
authors.lastname: Bertoft
mesh_terms: D000687:Amylopectin / Q000737:chemistry*; D004548:Elasticity; D006358:Hot Temperature; D012275:Oryza / Q000737:chemistry*; D014783:Viscosity
chemical_list: D000687:Amylopectin
keywords: African rice; Amylopectin; Internal chain distribution; Unit chain distribution