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International Starch Institute
Science Park Aarhus, Denmark
ISI 12-1e Determination of Acidity
| 1. Scope | The method is applicable to starch milk and hydrolysates
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LT 12. Dec. 1966 Rev. LT 16. Dec. 1997 |
| 2. Principle | Titration with NaOH to pH 8.3.
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| 3. Apparatus | 3.1 Burette | |
| 3.2 pH meter | ||
| 3.3 Volumetric flask 50 ml
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| 4. Reagents | 4.1 Sodium hydroxide 0.1 N | |
| 4.2 Phenolphtalein: 1 g in 1 l ethanol 90%
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| 5. Procedure | Fill volumetric flask (3.3) with liquid sample. Transfer to 300 ml conical flask. | |
Titration |
Add 1 ml (4.2) and titrate with (4.1) to faint persistent pink | or use pH meter to 8.3 |
| V = ml (4.2). N = normality of (4.2)
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| 6. Calculation | Calculate acidity as normality N of sample by averaging results of two
samples with one decimal. N = N V / 50
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| 7. Notes | J. Assoc. Off. Anal. Chem. 66 (1983) no. 6, 1395-1399 recommend pH 6.0 as end point, but AOAC limits this method to HFCS. | |
| Ph. EUR 4ed acidity test for starch. Add 10 g sample to 100 ml of alcohol (70 per cent V/V) R previously neutralised to 0.5 ml of phenolphthalein solution R and shake for 1 h. Filter and take 50 ml of the filtrate. Not more than 2.0 ml of 0.1 M sodium hydroxide is required to change the colour of the indicator. | ||
| 8. Reference | AOAC Official Methods of Analysis (15th edition) |
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Keywords: laboratory method determination acidity starch hydrolysate