ISI 11-1e Determination of pH and Acid Factor of Starch

ISI 11-1e Determination of pH and Acid Factor of Starch


1. ScopeThe method is applicable to commercial native starch

 

LT 02. Dec. 1964
Rev. LT 16. Dec. 1997
2. PrincipleTitration of 40 g starch in slurry with acid to pH 3.0.

 

3. Apparatus3.1 Analytical balance weighing to the nearest 0.1 mg.
3.2 pH meter

 

4. Reagents4.1 Hydrochloric acid 0.1 N

 

5. ProcedureWeigh 40.0 g sample to the nearest 100 mg in a 250 ml beaker
Add 100 ml distilled water and stir.

pH

Note pH of slurry

Titration

Titrate with burette and (4.1) to pH = 3.0

V = ml (4.2). N = normality of (4.2)

 

6. CalculationCalculate acid factor of sample by averaging results of two samples with one decimal.

Acid factor = 10 N V

Report pH of starch slurry as pH of starch with one decimal.

Eventually correct to value on sample dry matter.

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