BS EN ISO 6647-2:2020 pdf download.Rice – Determination of amylose content.
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified, and distilled or
demineralized water or water of equivalent purity.
5.1 Ethanol, a volume fraction of 95 %.
5.2 Sodium hydroxide:
a) 1 mol/l solution, for method A.
b) 2 mol/l solution, for method B.
5.3 Sodium hydroxide for blank solution:
a) 0,09 mol/l solution, for method A.
b) 0,18 mol/l solution, for method B.
5.4 Acetic acid, 1 mol/l solution.
5.5 Iodine solution.
Weigh (6.8), to the nearest 5 mg, 2,000 g of potassium iodide in a weighing bottle fitted with a stopper. Add sufficient water to form a saturated solution. Add 0,200 g of iodine, weighed to the nearest 1 mg. When all the iodine has dissolved, transfer the solution quantitatively to a 100 ml volumetric flask (6.4), make up to volume with water and mix.
Prepare a fresh solution on each day of use and protect it from light.
6 Apparatus
Usual laboratory apparatus and, in particular, the following.
6.1 Grinder, capable of reducing uncooked milled rice to flour that will pass through a 150 µm to
180 µm (100 mesh to 80 mesh) sieve. A cyclone mill with 0,5 mm screen is recommended.
6.2 Sieve, size 150 µm to 180 µm (100 mesh to 80 mesh).
6.3 Spectrophotometer, with matching cells, usually of path length 1 cm, capable of measuring
absorbance at 720 nm (or 620 nm or 680 nm).
6.4? Volumetric? flasks, 100 ml.
6.5 Boiling water bath, for method A only
6.6 Magnetic stirrer, capable of stirring at 950 r/min to 1 000 r/min, for method B only.
6.7? Conical? flasks, 100 ml.
6.8 Analytical balance, capable of weighing to the nearest 0,000 1 g.
6.9 Pipettes, of capacity 1 ml, 2 ml, 5 ml and 10 ml.
7 Sampling
A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage.
Sampling is not part of the method specified in this document. A recommended sampling method is given in ISO 24333.
8 Procedure
8.1 Determination of moisture
On a separate portion of the laboratory sample and the standard samples, carry out a moisture
determination in accordance with ISO 712.
8.2 Preparation of test sample
In the grinder (6.1), grind at least 4 g of milled rice that will pass through the sieve (6.2).
8.3 Test portion and preparation of the test solution
8.3.1 Weigh (6.8) 100 mg ± 0,5 mg of the test sample (see 8.2) into a 100 ml conical flask (6.7). To this test portion, carefully add 1 ml of ethanol (5.1) using a pipette, washing down any of the test portion adhering to the side of the flask. Shake slightly in order to wet the entire sample.BS EN ISO 6647-2 pdf download.