ISI 09-2e Determination of Fibre in Starch by Weight

ISI 09-2e Determination of Fibre in Starch by Weight


1. ScopeThe method is applicable to native potato and cassava starch

 

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

 

Cornstarches do not filter properly.
3. Apparatus3.1 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. Reagents4.1 Dilute hydrochloric acid 0.1 N

 

5. Procedure100.0 g (w1) sample is slurried in a 1000 ml conical flask with 600 ml acid (4.1)

 Hydrolysis

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

 Filtration

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)

Blind

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. CalculationCalculate 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. NotesAlternative: 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. ReferencesSimilar AOAC method for crude fibre may be applied as more specific for residual plant fibre.AOAC method detects lignin and cellulose
9. Image


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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