Commission Regulation (EC) No 273/2008 (repealed)Show full title

ANNEX XIX (Article 15)

DETERMINATION OF MOISTURE IN ACID BUTTERMILK POWDER

1. SCOPE

To determine the moisture content of acid buttermilk powder originally intended for animal feedingstuffs.

2. PRINCIPLE

The sample is dried under vacuum. The loss of mass is determined by weighing.

3. APPARATUS

3.1. Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg

3.2. Dishes of non-corrodible metal or of glass with lids ensuring airtight closure; working surface allowing the test sample to be spread at about 0,3 g/cm²

3.3. Adjustable electrically heated vacuum oven fitted with an oil pump and a mechanism for introducing hot air dried through a tower containing for example calcium oxide or calcium sulphate (containing moisture indicator)

3.4. Desiccator with an efficient drying agent

3.5. Drying oven ventilated, thermostatically controlled, at 102 ± 2 °C.

4. PROCEDURE

Heat a dish (3.2) with its lid in the oven (3.5) for at least one hour. Place the lid on the container, immediately transfer to a desiccator (3.4) allow to cool to room temperature and weigh to the nearest 1 mg, recording the mass to 0,1 mg.

Uncover the dish and transfer about 5g of sample into the dish and weigh to the nearest 1 mg, recording the mass to 0,1 mg. Place the dish with its lid in the vacuum oven (3.3) preheated to 83 °C. To prevent the oven temperature from falling unduly, introduce the dish as rapidly as possible.

Bring the pressure up to 100 Torr (13,3 kPa) and leave to dry to constant weight (approximately 4 hours) at this pressure in a current of hot dry air.

Reckon drying time from the moment when the oven returns to 83 °C. Carefully bring the oven back to atmospheric pressure. Open the oven, place the lid on the dish immediately, remove the dish from the oven, leave to cool for 30 to 45 minutes in a desiccator (3.4) and weigh to the nearest 1 mg recording the mass to 0,1 mg. Dry for an additional 30 minutes in the vacuum oven (3.3) at 83 °C and reweigh. Repeat the heating and weighing procedure until the mass of the dish with its lid decreases by 1 mg or less, or increases between two successive weighings. Take for the calculation the lowest mass recorded.

5. CALCULATION

% Moisture = (m₁ – m₂) / (m₁ – m₀) × 100 %

Where:

m₀

is the mass of the dish and the lid;

m₁

is the mass of the dish, the lid and the test portion before drying;

m₂

is the mass of the dish, the lid and the test portion after drying.

Record the result to the nearest 0,1 g / 100 g.

6. PRECISION

6.1. Repeatability limit

The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of the cases be greater that 0,4 g water/ 100 g buttermilk powder.

6.2. Reproducibility limit

The absolute difference between two independent single test results, obtained using the same method on identical test material in different laboratories by different operators using different equipment will in not more than 5 % of cases be greater than 0,6 g water/100 g acid buttermilk powder.

6.3. Source of precision data

The precision data were determined from an experiment conducted in 1995 involving eight laboratories and 12 samples (6 blind duplicates).