ANNEX II U.K.METHODS OF ANALYSIS RELATING TO THE COMPOSITION OF EDIBLE CASEINS AND CASEINATES

METHOD 1 U.K.

DETERMINATION OF MOISTURE CONTENT U.K.

1. SCOPE AND FIELD OF APPLICATION U.K.

This method determines the moisture content in:

• acid caseins

• rennet caseins

• caseinates

2. DEFINITION U.K.

The moisture content of caseins and caseinates: the loss of mass as determined by the method specified.

3. PRINCIPLE U.K.

The residual mass of a test portion is determined after drying at atmospheric pressure in an oven at 102 ^oC ± 1 ^oC to constant mass. The loss of mass is calculated as a percentage by mass of the sample.

4. APPARATUS U.K.

4.1. Analytical balance U.K.

4.2. Dishes, flat-bottomed and of material non-corrodible under the conditions of test e.g. nickel, aluminium, stainless steel or glass. The dishes must have lids which fit tightly but which can readily be removed. Suitable dimensions are: diameter 60 to 80 mm and depth about 25 mm. U.K.

4.3. Atmospheric pressure drying oven, well ventilated, thermostatically controlled with temperature regulation (at 102 ^oC ± 1 ^oC). The temperature should be uniform throughout the oven. U.K.

4.4. Desiccator, containing freshly activated silica gel with a water content indicator or an equivalent desiccant. U.K.

4.5. Suitable device for handling dishes, e.g. laboratory tongs. U.K.

5. PROCEDURE U.K.

5.1. Preparation of the test sample U.K.

As described in Section 1.2 of the General Provisions.

5.2. Preparation of the dish U.K.

5.2.1. Heat the uncovered dish and its lid (4.2) in the oven (4.3), controlled at 102 ^oC ± 1 ^oC, for at least one hour. U.K.

5.2.2. Place the lid on the dish, transfer the covered dish to the desiccator (4.4), allow to cool to the temperature of the balance room and weigh to the nearest 0,1 mg (m₀). U.K.

5.3. Test portion U.K.

Place 3 to 5 grams of the test sample (5.1) into the dish, cover with the lid and weigh to the nearest 0,1 mg (m₁).

5.4. Determination U.K.

5.4.1. Uncover the dish and place it with its lid in the oven (4.3), controlled at 102 ^oC ± 1 ^oC, for four hours. U.K.

5.4.2. Replace the lid on the dish, transfer to the desiccator, allow to cool to the temperature of the balance room and weigh to the nearest 0,1 mg. U.K.

5.4.3. Uncover the dish and heat it again, with its lid, in the oven for one hour. Then repeat operation 5.4.2. U.K.

5.4.4. If the mass obtained in 5.4.3 is less than the mass obtained in 5.4.2 by more than 1 mg, repeat operation 5.4.3. U.K.

If an increase in mass occurs, use the lowest recorded mass in the calculation (6.1).

Let the final weight recorded be m₂g. The total drying time should not normally exceed six hours.

6. EXPRESSION OF RESULTS U.K.

6.1. Method of calculation U.K.

The loss of mass on drying of the sample, expressed as a percentage by mass, is given by:

×

m₀

=

mass, in g of the dish and its lid after process 5.2;

m₁

=

mass, in g of the dish, its lid and the test portion before drying (process 5.3);

m₂

=

mass, in g of the dish, its lid and the test portion after drying (process 5.4.3 or 5.4.4).

Calculate the loss on drying to the nearest 0,01 %.

6.2. Repeatability U.K.

The difference in results between two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst, under the same conditions, shall not exceed 0,1 g of moisture per 100 grams of product.

This repeatability interval should be achieved in 95 % of the times that the method is carried out.