Determination of Water Content in Anhydrous milk fat Using Karl Fischer Titration

Product Group

Foodstuffs

General Information concerning the product group

Foodstuffs

Foodstuffs encompass the most diverse products. Depending on whether carbohydrate-rich, fatty or proteinrich substances are under investigation, different working techniques are favourable. Complex matrices that dissolve slowly, or where the water can only be slowly extracted, necessitate the use of solubilisers. In addition, titration under heating and the application of a homogeniser to accelerate water release are expedient.

Special Information concerning the sample and the methods

The solubility of anhydrous milk fat in methanol is rather poor. Titration has to be performed with special KF solvents for oils or fats. Alternatively solubilisers, like chloroform or alkylacetate, can be added. The use of a titrant with a factor of 2 mg/mL is recommended, in order to reduce the sample size. Titration under warm conditions (40 - 50 °C) increases the release of water. Alternatively, the use of a homogeniser is favourable.

Titration one component system

Reagents:

Titrant
188005 Aquastar™ - CombiTitrant 5 - One component reagent for volumetric Karl Fischer titration, 1 mL = approx. 5 mg water
or
188002 Aquastar™ - CombiTitrant 2 - One component reagent for volumetric titration, 1 mL = appr. 2 mg water

Solvent
60 mL 188021 Aquastar™ - CombiSolvent fats - Solvent for volumetric Karl Fischer titration with one component reagents for fats
or
50 mL / 10 mL 188021 / 102445 Aquastar™ - CombiSolvent fats / chloroform - solvent mixture for one component titration

Titration Parameters:
Extraction time: 180 sec. (or 60 sec. with homogeniser)
Temperature: 50°C
Default titration settings, e.g.:
I(pol) = 20 - 50 µA, U(EP) = 100 - 250 mV
Stop criterion: drift < 20 µL/min

Sample size:
1.0 - 2.0 g

Procedure:
The titration medium is first placed into the cell . After heating up to 50 °C, the solvent is titrated dry by means of the titrant. Then the sample is added (exact sample weight determination before and after addition) and the titration is started. For complete dissolution of the sample a stirring time of 180 seconds is recommended. If a homogenizer is used, titration can be performed at room temperature.

Materials

     
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