Journal of AOAC International · 1995 · 438 citations · 0 references
AgricultureBiochemistryFood ScienceFood AnalysisFood ChemistryHuman NutritionCarbohydrate AnalysisCarbohydrates In FoodsDietary Fiber AnalysisDietary Fiber In CerealsFood CompositionProtein AnalysisCarbohydrate Hydrolysis By Alpha-amylaseDietary Fiber CharacterizationDietary Fiber ExtractionFiber Composition AnalysisNonstarch PolysaccharidesPolysaccharide CharacterizationTotal Dietary FiberUronic Acid Content
The study aimed to determine the dietary fiber content and composition of various foods using the Uppsala method. The Uppsala method combines enzymatic digestion, ethanol precipitation, acid hydrolysis, GC analysis of neutral polysaccharides, colorimetric uronic acid measurement, and gravimetric Klason lignin determination, with total dietary fiber calculated as the sum of non‑starch polysaccharides and lignin, and was applied by nine laboratories to eight dried products. Across the nine laboratories, total dietary fiber ranged from 4.6 % to 84.3 % (average RSDR 8.4 %), neutral polysaccharides from 3.8 % to 64.1 % (average RSDR 7.5 %), individual sugars and uronic acids >1 % showed RSDR 3.3–22.8 %, Klason lignin had excellent RSDR only for a high‑content wheat bran sample, and the method has been adopted by AOAC International.
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 alpha-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.