ISI 01-1e Determination of Dry Matter in Starch by Oven Drying at 130 oC

1. Scope The method is applicable to starch in native or modified form.
LT 15 Dec. 1964
Rev.: LT 21 Nov. 1997

2. Principle The sample is dried to constant weight.

3. Apparatus 3.2 Dish of aluminium or glass with tight-fitting lid
3.3 Electrically heated constant-temperature oven.

3.4 Desiccator with dry drying agent

4. Procedure An empty dish (3.2) is dried 1/2 hour in oven (3.3) at 130 oC. Cool dish in desiccator (3.4) to room temperature and weigh on balance (3.1) to the nearest 1 mg. Weight = w0  
Let cool 40 min

Distribute 5 g of sample in a uniform layer in dish. Close lid and weigh to the nearest 1 mg. Weight = w1
Place the open dish with sample in oven preheated to 130 oC. Dry 90 minutes after oven has once again reached 130 oC.
Close lid and cool in desiccator for 30 to 45 minutes. Weigh immediately after removal from desiccator to the nearest 1 mg. Weight=w2

Dry starch absorbs atmospheric moisture rapidly. Therefore; close lid fast and keep desiccator in perfect condition.

Drying too long affects starch

5. Calculation Dry matter (DM) in percent of sample (average results of two samples to one decimal) =
DM % = 100 x (w2 - w0) / (w1 - w0)

6. Notes Dry matter determination by infrared drying to constant weight of sample placed directly on a laboratory balance gives comparable results. It is a reliable alternative without the risk of unintended moisture re-absorption associated with the oven drying method.
Alternative method is drying at 105 oCover night (min. 16 hours).

7. Reference International Standard: ISO 1666

Comments

Post a Comment

Popular posts from this blog

ISI 19-6e Determination of Viscosity of Starch by Brabender

Return 1. Scope The method is applicable to starch   LT 08.12.1966 Rev. LT 7. Feb. 2000. 2. Principle Viscosity of native and modified starch is measured during controlled heating and cooling   Dynamic viscosity 3. Apparatus 3.1 Brabender viscograph, 700 cmg cartridge. Bowl rotational speed: 75 rpm. Starting temperature: 45  o C. Subsequent rate of temperature increase and decrease: 1½  o C/min. Use standardisation kit for calibrating. Starting temperature = Start of test. 3.2 Beaker, 1000 ml 3.3 Laboratory scale   4. Procedure Weigh starch sample eq...
Read more

ISI 27-1e Determination of Reducing Power and DE by Lane and Eynon's method.

Return 1. Scope The method is applicable to all starch hydrolysis products.   LT 7/12 1966 Rev.: LT 3. May 1999 2. Principle The Lane and Eynon constant titre method. Mixed Fehling's solution is titrated with sample using methylene blue as indicator.   3. Reagents 3.1 Fehling stock solution A. Dissolve 69.3 g copper (II) sulphate pentahydrate (CuSO 4 , 5H 2 O) in distilled water to 1000.0 ml. 3.2 Fehling stock solution B. Dissolve 346 g potassium sodium tartrate tetrahydrate (KNaC 4 H4O 6 , 4H 2 O) and 100.0 g sodium hydroxide (NaOH) in distilled water to 1000,0 ml. Decant solution from sediment if necessary ...
Read more

ISI 14-2e Determination of Acetyl Content

  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. Calculatio...
Read more