Production and characterisation of two wheat-bran fractions: an aleurone-rich and a pericarp-rich fraction.
Wheat bran is a good source of dietary fibre in the form of cell walls, but contains a number of different cell types. We describe a large-scale procedure for the production of an aleurone-rich and a pericarp-rich fraction from hard, Australian wheat. The fractions were characterised by field-emission scanning electron microscopy, by using a range of bright-field stains, colour reagents, and fluorochromes, and by chemical analysis of the walls. The aleurone fraction included the seed coat with its cuticle. Only the pericarp walls showed a histochemical reaction for lignin. The concentrations of ester-linked ferulic acid and (1-->3),(1-->4)-beta-glucans were greater in the aleurone-rich fraction than in the pericarp-rich fraction. The results are consistent with the arabinoxylans in the walls of the pericarp-rich fraction being more highly substituted with arabinose than those in the walls of the aleurone-rich fraction. When the fractions were fed as a dietary supplement to rats and walls were isolated from the faeces, it was found that the pericarp walls were not degraded, but the aleurone walls were partially degraded.
Harris
Philip J
PJ
School of Biological Sciences, The University of Auckland, Auckland, New Zealand. p.harris@auckland.ac.nz
Chavan
Ramesh R
RR
Ferguson
Lynnette R
LR
D000818:Animals; D002473:Cell Wall / Q000737:chemistry / Q000648:ultrastructure; D003373:Coumaric Acids / Q000032:analysis; D004043:Dietary Fiber / Q000032:analysis; D005243:Feces; D005260:Female; D006651:Histocytochemistry; D008855:Microscopy, Electron, Scanning; D009005:Monosaccharides / Q000032:analysis; D011422:Propionates; D051381:Rats; D017208:Rats, Wistar; D012639:Seeds / Q000648:ultrastructure*; D014908:Triticum / Q000648:ultrastructure*
D003373:Coumaric Acids; D004043:Dietary Fiber; D009005:Monosaccharides; D011422:Propionates; C004999:ferulic acid; C495469:p-coumaric acid