Commission Regulation (EC) No 273/2008 (repealed)Show full title

5. PROCEDURE

5.1. Preparation of the test sample

5.1.1. Concentrated butter

Melt the sample in an oven at approximately 45 °C.

5.1.2. Butter

Melt the sample in an oven at approximately 45 °C and filter a representative portion through a filter containing about 10 g of anhydrous sodium sulphate (4.3) in an environment shielded from strong natural and artificial light and maintained at 45 °C. Collect a suitable amount of butterfat.

5.2. Determination

Weigh, to the nearest 1 mg approximately 1 g of concentrated butter (or extracted butterfat (5.1.2)), (M). Transfer quantitatively to a 20 ml (V) volumetric flask using petroleum spirit (4.2), make up to the mark and mix thoroughly.

Transfer an aliquot to a 1 cm cell and measure the absorbance at 440 nm, against a petroleum spirit blank. Obtain the concentration of apo-carotenic ester in the solution by referring to the obtained standard curve (C μ/ml).

5.3. Calibration

Pipette 0, 0,25, 0,5, 0,75 and 1,0 ml of apo-carotenic ester standard solution (4.1.2) into five 100 ml volumetric flasks. Dilute to volume with petroleum spirit (4.2) and mix.

The approximate concentrations of the solutions range from 0 to 2 μg/ml and are calculated accurately by reference to the concentration of the standard solution (4.1.2) (W × P) / 10 mg/ml. Measure the absorbances at 440 nm against a petroleum spirit (4.2) blank.

Plot the values of absorbance on the y axis against apo-carotenic ester concentration on the x axis. Calculate the equation of the standard curve.