Dietary Fiber Assay Kit

A simple and modified version of Prosky's method. Compared to conventional Prosky's method, it assures high measurement accuracy. Furthermore, enzyme treatment time is shortened.

Kit Contents

1. Thermostable alpha-Amylase Solution 1 vial x 20 mL


2. Protease Solution 1 vial x 20 mL


3. Amyloglucosidase Solution 1 vial x 20 mL


4. Diatomaceous Earth 1 vial x 100 g

Measurement Outline

1. Sample dissolved in MES/Tris buffer


2. Digestion with thermostable alpha-amylase


3. Digestion with protease and amyloglucosidase

for 30 minutes at pH 6.3 and 60 degrees C

4. Ethanol Precipitation

Leave 1 hour

5. Filtration


6. Wash with ethanol and acetone


7. Dry overnight


8. Kjeldahl Protein Determination and Ash Determination


9. Total Dietary Fiber Determination

1. Determination of total Dietary Fiber Contents

Digestible components in samples, such as starch and protein, are hydrolyzed
with alpha-amylase, protease, and amyloglucosidase, precipitate undecomposed residual macromolecule by adding quadruple volume 95% Ethanol, and then trapped with a glass filter crucible containing diatomaceous earth.
Total Dietary Fiber Contents are determined by deducting weight of protein and ash content from the dry weight of trapped residue on a glass filter crucible.

2. Fractional Analysis of Soluble Dietary Fiber Contents and Insoluble Dietary Fiber Contents

Digestible components in samples, such as starch and protein, are hydrolyzed with alpha-amylase, protease, and amyloglucosidase, then filtrated with a glass filter crucible containing diatomaceous earth.
Insoluble Dietary Fiber Contents are determined by deducting weight of protein and ash content from the dry weight of trapped insoluble residue on a glass filter crucible.
Meanwhile, add a quadruple volume 95% Ethanol into the filtrate, precipitate undecomposed residual soluble macromolecule, and trap with a glass filter crucible containing diatomaceous earth. Soluble Dietary Fiber Contents are determined by deducting weight of protein and ash content from the dry weight of the trapped precipitated residue on a glass filter crucible.
Total Dietary Fiber Contents are defined as the sum of Insoluble Dietary Fiber Contents and Soluble Dietary Fiber Contents.

3. Determination of Low-molecular Soluble Dietary Fiber

Specific Low-molecular Soluble Dietary Fibers, which are not precipitated even by addition of a quadruple volume of 95% Ethanol, are determined by high-performance liquid chromatography.
After digestible components such as starch and protein in samples are hydrolyzed with alpha-amylase, protease, and amyloglucosidase, the undecomposed residual macromolecule are precipitated by adding a quadruple volume of 95% Ethanol. Then filter it with a glass filter crucible containing diatomaceous earth.
Proteins, organic acids and inorganic salts in the filtrate are removed with ion-exchange resin, and then the solution is applied to high-performance liquid chromatography. Low-molecular Soluble Dietary Fiber Content is determined by the ratio of the peak area of the sample with that of glucose (internal standard) on the chromatogram.
Meanwhile, Insoluble and Soluble Macromolecule Dietary Fiber Content is determined by deducting weight of protein and ash content from the dry weight of the trapped precipitated residue on a glass filter crucible.
Total Dietary Fiber Contents is defined as sum of Low-molecular Soluble Dietary Fiber Contents and Insoluble and Soluble Macromolecular Dietary Fiber Contents.