BS EN ISO 6647-2 pdf free download

BS EN ISO 6647-2 pdf free download. Rice – Determination of amylose content.
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. 8.3.2 Method A Pipette (6.9) 9,0 ml of sodium hydroxide solution [5.2 a)] into the conical flask and mix. Then heat the mixture on a boiling water bath (6.5) for 10 min to disperse the starch. Allow to cool to room temperature and transfer quantitatively to a 100 ml volumetric flask (6.4). Make up to volume with water and mix vigorously. 8.3.3 Method B Pipette (6.9) 9,0 ml of sodium hydroxide solution [5.2 b)] into the conical flask and mix. Stir the mixture using a magnetic stirrer (6.6) for 10 min to obtain the dispersion. Remove the stirrer and transfer quantitatively to a 100 ml volumetric flask (6.4). Make up to volume with water and mix vigorously. It is recommended to swirl the liquid in the volumetric flask before adding the water and after making up to volume. 8.4 Preparation of the blank solution Prepare a blank solution using the same procedure and the same quantities of all the reagents as in the determination, but using 5,0 ml of sodium hydroxide solution [5.3 a) for method A and 5.3 b) for method B] instead of the test solution. 8.5 Preparation of the calibration graph 8.5.1 Preparation of the set of calibration solutions Select at least four rice samples with a distribution of amylose mass fraction in the measured range. For each sample, ensure that the amylose mass fraction has been determined by the reference method specified in ISO 6647-1, independently, 20 times. Alternatively, a certified reference material may be used. Prepare the calibration solutions as in 8.2 and 8.3. 8.5.2 Colour development and spectrophotometric measurements Pipette (6.9) a 5,0 ml aliquot of each calibration solution into a series of five volumetric flasks (6.4) each containing about 50 ml of water. Pipette (6.9) 1,0 ml of acetic acid (5.4) for method A or 2,0 ml for method B and mix. Then pipette (6.9) 2,0 ml of iodine solution (5.5), make up to the mark with water and mix. Allow to stand for 10 min. Measure the absorbance at 720 nm against the blank solution (see 8.4) using the spectrophotometer (6.3). Measurement wavelengths of 620 nm or 680 nm can also be used (see Annex A). 8.6 Determination Pipette (6.9) a 5,0 ml aliquot of the test solution (see 8.3) into a volumetric flask (6.4) containing about 50 ml of water and proceed according to 8.5.2, starting with the addition of acetic acid (5.4). Measure the absorbance at 720 nm (or at 620 nm or at 680 nm, see Annex A) against the blank solution (see 8.4) using the spectrophotometer (6.3). Instead of manual spectrometric measurements, an automatic analyser, e.g. a flow injection analyser, may be used (see ISO 6647-1:2020, Annex C). Carry out two determinations on separate test portions taken from the same test sample. If double determinations are made, based on two independent preparations of the sample (see 8.2), this should be noted in the test report.BS EN ISO 6647-2  pdf download.