Total Dietary Fiber Determined as Neutral Sugar Residues, Uronic Acid Residues, and Klason Lignin (The Uppsala Method): Collaborative Study

Abstract

A joint AOAC/American Association of Cereal Chemists (AACC) collaborative study was conducted to determine by the Uppsala method the dietary fiber content and its composition in various foods. The method includes preparation of a residue by treatment with thermostable α-amylase and amyloglucosidase and then ethanol precipitation of solubilized dietary fiber components while leaving low-molecular weight carbohydrates in solution. After acid hydrolysis of residue, neutral polysaccharide residues are determined as alditol acetates by gas-liquid chromatography, uronic acid residues are determined by colorimetry, and ash-free acid-insoluble residue (Klason lignin) is determined gravimetrically. Total dietary fiber, including enzyme-resistant starch, is calculated as the sum of nonstarch polysaccharide residues and Klason lignin. Nine laboratories completed the study, analyzing in duplicate 8 unknown dried products that included 4 cereal products, green peas, potato fiber, carrots, and apples. Total dietary fiber contents of products tested ranged from 4.6 to 84.3%, with an average RSDR value of 8.4% (range, 4.8–11.1%). Total neutral polysaccharide residues ranged from 3.8 to 64.1%, with an average RSDR value of 7.5% (range, 5.4–10.5%). Individual neutral sugars (rhamnose, arabinose, xylose, mannose, galactose, and glucose) and uronic acid residues present at more than 1% generally had good RSDR values (3.3– 22.8%), whereas, as expected for Klason lignin, only the wheat bran sample with a high content (16%) had an excellent RSDR value (5.0%). The gas chromatographic-colorimetric-gravimetric method (Uppsala method) for determination of total dietary fiber (as neutral sugar residues, uronic acid residues, and Klason lignin) has been adopted first action by AOAC INTERNATIONAL.

Expression of an apoplast‐localized BURP‐domain protein from soybean (GmRD22) enhances tolerance towards abiotic stress

“…For each sample, 30 to 40 seedlings of A. thaliana or rice were pooled and the aerial parts were ground into fine powder in liquid nitrogen before measurement. Pectin assay was performed as previously described (Theander et al 1995;AOAC 2000b). Approximately 200 mg of the lyophilized powder was used for each sample.…”

Maize Stem Tissues: Impact of Development on Cell Wall Degradability

“…At the conclusion of incubations, the entire contents of the centrifuge tubes were frozen at 2208C and lyophilized before analysis of the nondegraded residual cell wall material. Dried residues from the in vitro incubations were analyzed for remaining cell wall polysaccharide components (glucose, xylose, arabinose, galactose, mannose, rhamnose, fucose, and uronic acids) by the Uppsala Dietary Fiber procedure (Theander et al, 1995). Glucuronic acid was used as the standard for the colorimetric determination of uronic acids (Ahmed and Labavitch, 1977).…”

Lignin and Etherified Ferulates Affect Digestibility and Structural Composition of Three Temperate Perennial Grasses

“…The concentration of NDF was determined using the procedure of Van Soest et al (1991), omitting the sodium sulfite, a-amylase, and ash-correction steps. Klason lignin concentration was measured as the ash-free residue remaining after cell wall polysaccharide hydrolysis (Theander et al, 1995). The Klason lignin procedure was used to remain consistent with our previous work on selection and breeding for lignin and etherified ferulate (Casler and Jung, 1999;Jung and Casler, 1991), and because it provides a more accurate estimate of total lignin in the cell wall Lowry et al, 1994;Jung et al, 1999).…”