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International Starch Institute
Science Park Aarhus, Denmark
ISI 05-2e Determination of Dry Matter in Oven at 105 oC

1. Scope The method is applicable to starch, dextrose - anhydrous and monohydrate - and total sugar.

 

LT 15. Dec- 1964
Rev. LT 21. Nov. 1997
2. Principle The sample is dried at 105 oC

 

3. Apparatus 3.1 Analytical balance weighing to the nearest 1 mg.
3.2 Dish of aluminium or glass with tight-fitting lid
3.3 Electrically heated oven.
3.4 Desiccator with dry drying agent

 

4. Procedure Dry dish (3.2) 1/2 hours in oven (3.3) at 105 oC.
Cool dish in desiccator (3.4) to room temperature and weigh on balance (3.1) to nearest 1 mg. Weight = w0 Cool 40 min
Weigh 2 g of sample in dish to the nearest 1 mg. Weight = w1. Take 5 g total sugar
Dry dish and sample over night (min. 16 hours) in vacuum at 105 oC With one dying step only time may be extended
Close lid and cool in desiccator for 1 hour. Weigh immediately after removal from desiccator to nearest 1 mg. Weight=w2

 

Possibly re-heat to constant weight
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 Alternative method: Drying at 70 oC or 100 oC in vacuum.

The European Pharmacopoeia 4 specifies for potato and wheat starch drying at 130 oC for 90 min and for maize and rice starch drying at 100-105 oC to constant weight.

7. Reference International Standard: ISO 1741

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Keywords: laboratory method determination dry matter substance starch oven drying