Recovery of soluble dietary fiber is dependent on the method of analysis.
The effects of different methods on the distribution of total neutral sugars (TNS), uronic acids (UA), and beta-glucans (beta G) between the soluble (S) and insoluble (I) fractions of dietary fiber (DF) were determined for peas, kidney beans, oat bran, rice, and macaroni. Incorporation of a protease step into the Theander method "A" modestly increased, and addition of a pepsin digestion further increased the proportion of total fiber recovered in the S fraction. The effect of extraction method on the distribution of TNS, UA, and beta G between the S and I fractions varied with the food. The three methods measured the same total DF in a food and 1-3% starch in the I fraction of peas and kidney beans. Use of dimethyl sulfoxide to solubilize starch, or elevated temperature to extract S components, had no effect on the distribution of DF between S and I fractions of peas and macaroni. Incomplete protein hydrolysis did not always lower Klason lignin and excluding lignin from the fiber complex did not always substantially increase the S fraction.
Marlett
J A
JA
Department of Nutritional Sciences, University of Wisconsin-Madison 53706.
Chesters
J G
JG
Longacre
M J
MJ
Bogdanske
J J
JJ
D004040:Dietary Carbohydrates / Q000032:analysis; D004043:Dietary Fiber / Q000032:analysis*; D004121:Dimethyl Sulfoxide; D005504:Food Analysis; D005936:Glucans / Q000032:analysis; D006868:Hydrolysis; D011506:Proteins / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013696:Temperature; D014574:Uronic Acids / Q000032:analysis
D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D005936:Glucans; D011506:Proteins; D014574:Uronic Acids; D013213:Starch; D004121:Dimethyl Sulfoxide