title: Structure of clusters and building blocks in amylopectin from African rice accessions.
abstract: Enzymatic hydrolysis in combination with gel-permeation and anion-exchange chromatography techniques were employed to characterise the composition of clusters and building blocks of amylopectin from two African rice (Oryza glaberrima) accessions-IRGC 103759 and TOG 12440. The samples were compared with one Asian rice (Oryza sativa) sample (cv WITA 4) and one O. sativa×O. glaberrima cross (NERICA 4). The average DP of clusters from the African rice accessions (ARAs) was marginally larger (DP=83) than in WITA 4 (DP=81). However, regarding average number of chains, clusters from the ARAs represented both the smallest and largest clusters. Overall, the result suggested that the structure of clusters in TOG 12440 was dense with short chains and high degree of branching, whereas the situation was the opposite in NERICA 4. IRGC 103759 and WITA 4 possessed clusters with intermediate characteristics. The commonest type of building blocks in all samples was group 2 (single branched dextrins) representing 40.3-49.4% of the blocks, while groups 3-6 were found in successively lower numbers. The average number of building blocks in the clusters was significantly larger in NERICA 4 (5.8) and WITA 4 (5.7) than in IRGC 103759 and TOG 12440 (5.1 and 5.3, respectively).
authors.affiliation: Department of Food Science, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada. Electronic address: jgayin@uoguelph.ca.
authors.forename: Joseph
authors.initials: J
authors.lastname: Gayin
authors.affiliation: Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, ON N1G 5C9, Canada. Electronic address: elsayed.abdelaal@agr.gc.ca.
authors.forename: El-Sayed M
authors.initials: el-SM
authors.lastname: Abdel-Aal
authors.affiliation: Department of Food Science, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada. Electronic address: mmarcone@uoguelph.ca.
authors.forename: Massimo
authors.initials: M
authors.lastname: Marcone
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: D000349:Africa; D000687:Amylopectin / Q000737:chemistry* / Q000378:metabolism; D001208:Asia; D003912:Dextrins / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis; D012275:Oryza / Q000737:chemistry*
chemical_list: D003912:Dextrins; D000687:Amylopectin
keywords: African rice; Amylopectin; Building blocks; Clusters; Starch