| Home | Profile | Market Place | Sweeteners | Lab Methods | Glossary | Search |
| Master Index | Environment | Application | Starch | Statistics | Tables | Write us |
International Starch Institute
Science Park Aarhus, Denmark
ISI 14-2e Determination of Acetyl Content
| 1. Scope | The method is applicable to acetylated starch
|
KM Rev. LT 14 Sep 1999 |
| 2. Principle | Bound acetyl reacts with strong alkali and excess alkali is titrated
|
|
| 3. Apparatus | 3.1 Burette 3.2 Conical flask, Erlenmeyer 250 ml with stopper
|
|
| 4. Reagents | 4.1 Sodium hydroxide 0.1 N 4.2 Sodium hydroxide 0.45 N 4.3 Hydrochloric acid 0.2 N 4.4 Phenolphthalein: 1 g in 1 l ethanol 90%
|
|
| 5. Procedure | Weigh 5 g of sample to the nearest mg. Transfer to conical flask (3.2) and disperse in 50 ml distilled water. Add a few drops of indicator (4.4) and titrate with (4.1) to permanent pink colour. | |
Bound acetyl reaction |
Add 25.0 ml of NaOH 0.45 N (4.2). Stopper and shake vigorously for ½ hour | Use mechanical shaker |
Titration |
Flush stopper and neck of flask with a little distilled water and titrate excess alkali with 0.2N HCL to disappearance of pink colour. | |
Blank |
25.0 ml 0.45N NaOH (4.2) is titrated as a blank
|
|
| 6. Calculation | Calculate acetyl groups by averaging results of two samples with two
significant digits: Acetyl groups % of sample = ((b-s) * N * 0.043 * 100) / w ; where b = ml 0.2 N HCl used to titrate blank Correct eventually to acetyl groups % of sample dry matter |
Molecular weight of CH3CO = M = 43 |
| 7. Notes | Alternative determination of acetyl by enzymatic method ISO 11213
|
|
| 8. Reference | JECFA |
| Top of Page | LabIndex |
Copyright© 1999. Read Disclaimer notice.
All rights reserved. International Starch Institute, Science Park Aarhus, Denmark.
Keywords: laboratory method determination acetyl group starch