BS EN ISO 6647-2:2020 pdf free.Rice – Determination of amylose content.
Rice is ground to a very fine flour to break up the endosperm structure in order to aid complete dispersion and gelatinization. A test portion is dispersed in a sodium hydroxide solution. An aliquot portion is taken to which is added an iodine solution. The absorbance, at 720 nm, of the colour complex formed is then determined using a spectrophotometer.Measurement wavelengths of 620 nm or 680 nm can also be used.The amylose mass fraction of the sample is then read from a calibration graph, which is prepared by using rice samples of known amylose mass fraction, determined using the reference method specified above.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.Weigh (6.8) 100 mg土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. 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.  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.BS EN ISO 6647-2 pdf download.