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International Starch Institute
Science Park Aarhus, Denmark
ISI 09-2e Determination of Fibre in Starch by Weight

1. Scope The method is applicable to native potato and cassava starch


LT 1994
Rev. LT 11. Dec. 1997
2. Principle Starch is hydrolysed and filtered. Fibre defined as non-soluble impurities are retained, dried and determined by weight.


Cornstarches do not filter properly.
3. Apparatus 3.1 Analytical balance weighing to the nearest 1 mg.

3.2 Shaking boiling water bath.

3.3 Büchner funnel or Sartorius 250 ml glass vacuum filter funnel.
Use a high flux filter. Do not use a glass frit filter support
4. Reagents 4.1 Dilute hydrochloric acid 0.1 N


5. Procedure 100.0 g (w1) sample is slurried in a 1000 ml conical flask with 600 ml acid (4.1)


Place flask in boiling water bath (3.2) for 30 min Shake min. until starch is gelatinised


Filter hot on filter (3.3). Flush flask and filter with 100 ml hot water. Increase hydrolysis parameters if flux too low
Dry filter at 105 oC over night - min 12 hours. Weigh filter to nearest 1 mg (m1)


10.0 g (w0) sample is slurried in a 100 ml conical flask with 60 ml acid (4.1). Hydrolyse and filter as above. Weigh filter to nearest 1 mg (m0)


6. Calculation Calculate fibre of sample by averaging results of two samples with two decimals.

Fibre % = 100 * ((m1 - m0) / (1 - w0 / w1)) / w1

Eventually correct to value on sample dry matter.


7. Notes Alternative: Substitute acid with heat stable alpha-amylase. It is essential to hydrolyse to obtain high flux through filter. Use a filter holder with a screen filter support or other non-clogging support. 


8. References Similar AOAC method for crude fibre may be applied as more specific for residual plant fibre. AOAC method detects lignin and cellulose
9. Image

filterholder.jpg (6607 bytes)

Sartorius  filter funnel(min 250 ml) with glass vacuum holder for 47 mm  filters with PTFE-coated steel screen filter support

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Keywords: laboratory method determination pulp fibre fiber starch