EN 1131-1994 pdf download.Fruit and vegetable juices – Determination of the relative density.
This EN 1131 specifies a method for the determination of the relative density d2°c,0 c of fruit and vegetable juices and related products.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. ISO 5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. Iso :3696:1987, Water for analytical laboratory use — Specification and test methods.
3 Definition
For the purposes of this standard, the following definition applies:
3.1
relative density, d2ooc,)Qc
the mass of a known volume of the test sample at 20 °C divided by the mass of an equal volume of air-free water at 20 °C (pure number without units)
4 Principle
The relative density is determined using a pykno meter.
5 Reagents
5.1 General
Use only degassed water in accordance with at least grade 3 of ISO 3696: 1987.
5.2 Potassium dichromate-suifuric acid solution, to clean the pyknometer (6.4)
SAFETY WARNING. Extreme care should be exercised when using and transporting potassium dichromatesulfuric acid solution, which is a strong acid and oxidant. Take appropriate measures to protect skin, eyes and clothing. Never add water to this solution, since a large amount of heat will he generated locally, resulting in danger of sputtering. Take appropriate measures when disposing of used solutions.
5.3 Appropriate glass cleaning agent, with cleansing effect comparable to (5.2) [alternative to (5.2)1.
The relative density is determined using a pyknometer.
5 Reagents
5.1 General
Use only degassed water in accordance with at least grade 3 of ISO 3696: 1987.
5.2 Potassium dichromatc-suifuric acid solution, to clean the pyknometer (6.4)
SAFETY WARNING. Extreme care should be exercised when using and transporting potassium dichromate-sulfuric acid solution, which is a strong acid and oxidant. Take appropriate measures to protect skin, eyes and clothing. Never add water to this solution, since a large amount of heat will l)e generated locally, resulting in danger of sputtering. Take appropriate measures when disposing of used solutions.
5.3 Appropriate glass cleaning agent, with cleansing effect comparable to (5.2) [alternative to (5.2)1.
If necessary, clean the pyknometer (6.4) with hot potassium dichromate-sulfuric acid solution (5.2) or a proprietary cleansing agent (5.3).
SAFETY WARNING. See safety warning in (5.2). Rinse the pyknometer (6.4) several times with water and dry gently. Avoid drying conditions that might influence the volume of the pyknometer. After allowing the pyknometer to cool to ambient temperature in the desiccator (6.1) place it in the balance-case and allow to equilibrate in the balance-case for 15 mm. weigh the pyknometer (6.4) to an accuracy of 4 decimal places. Carry out the rinsing, drying and weighing procedure a total of three times and then determine the mean mass value (rn8).
7.3 Weighing of the pyknorneter filled with water
Fill the pyknometer (6.4 or 6.5) to above the mark with freshly boiled air-free water, stopper and place in the water bath (6.2) at 20 °C ± 0,05 °C for 30 min.
While still keeping it in the water bath, bring the volume of the water to the mark by means of the bent glass capillary tube (6.10).
Ensure that the adjustment of the liquid level is always carried out by the same method.
The surface of the water forms a curved area in the neck of the pyknometer. Adjust the liquid so that in transmitted light, the lower edge of the surface just touches the pyknometer mark. Then dry the empty part of the pyknometer neck using the filter paper wicks (6.9). Replace the stopper, remove the
pyknometer from the water-bath, dry well on the outside and place in the balance-case for 15 mm.
Weigh the pyknometer to an accuracy of 4 decimal places. Carry out this procedure of filling and
weighing three times and then determine the mean mass (nib).
7.4 Weighing of the pyknometer filled with test sample
Empty the pyknometer after weighing it (7.3), then either dry as in 7.2 or rinse repeatedly with the
sample to he examined. Fill the pyknometer with the sampk and proceed as in 7.3 to determine the mean mass (,n4.).
8 Calculation
Calculate the relative density d2øe0o of the sample as follows:EN 1131-1994 pdf download.