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International Starch Institute
Science Park Aarhus, Denmark
ISI 11-1e Determination of pH and Acid Factor of Starch
| 1. Scope | The method is applicable to commercial native starch
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LT 02. Dec. 1964 Rev. LT 16. Dec. 1997 |
| 2. Principle | Titration of 40 g starch in slurry with acid to pH 3.0.
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| 3. Apparatus | 3.1 Analytical balance weighing to the nearest 0.1 mg. | |
| 3.2 pH meter
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| 4. Reagents | 4.1 Hydrochloric acid 0.1 N
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| 5. Procedure | Weigh 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)
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| 6. Calculation | Calculate 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. |
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| Eventually correct to value on sample dry matter. |
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Keywords: laboratory method determination pH acid factor starch