Content and molecular-weight distribution of dietary fiber components in whole-grain rye flour and bread.
Content of dietary fiber and dietary fiber components in whole-grain rye (n = 18) were analyzed. The average total content, when fructan was included, was for dietary fiber 19.9% (range of 18.7-22.2%) and for extractable dietary fiber 7.4% (range of 6.9-7.9%). Arabinoxylan was the main dietary fiber component, with an average total content of 8.6%, followed by fructan (4.1%). During baking of whole-grain rye bread, only small changes in total content of arabinoxylan, arabinogalactan, and beta-glucan occurred, while the content of resistant starch increased and the content of fructan decreased in a baking-method-dependent manner. The molecular-weight distribution of extractable arabinoxylan in the flour was analyzed with a new method and ranged from 4 x 10(4) to 9 x 10(6) g/mol, with a weight average molecular weight of about 2 x 10(6) g/mol. During crisp bread making, only a limited degradation of arabinoxylan molecular weight was detected, while a notable degradation was observed in sour-dough bread. The molecular weight of extractable beta-glucan in the whole-grain rye flour ranged from 10(4) to 5 x 10(6) g/mol, with a weight average molecular weight of 0.97 x 10(6) g/mol. During bread making, the molecular weight of the beta-glucan was substantially degraded.
Andersson
Roger
R
Department of Food Science, Swedish University of Agricultural Sciences (SLU), Post Office Box 7051, SE-750 07 Uppsala, Sweden. roger.andersson@lmv.slu.se
Fransson
Gunnel
G
Tietjen
Markus
M
Aman
Per
P
D001939:Bread / Q000032:analysis*; D004043:Dietary Fiber / Q000032:analysis*; D005433:Flour / Q000032:analysis*; D008970:Molecular Weight; D012434:Secale / Q000737:chemistry*; D014990:Xylans / Q000032:analysis; D047071:beta-Glucans / Q000032:analysis
D004043:Dietary Fiber; D014990:Xylans; D047071:beta-Glucans; C085118:arabinoxylan