ISO 665:2020 pdf download – Oilseeds – Determination of moisture and volatile matter content
7.1 Prepare the test sample by reducing the laboratory sample in accordance with ISO 664. If large non-oleaginous foreign bodies have been separated before the reduction of the laboratory sample, make allowance for this in the calculation (see 9.2). According to the requirements of the contract, take a sample as received or after separation of the impurities.
7.2 In the case of copra, grate the product by hand or, preferably, use a mechanical grater (5.3) that allows the whole sample to be treated. When grating by hand, which does not allow all the analysis sample to be grated, endeavour to obtain a test sample that is as representative as possible and, to this end, take account of the size and colour of different fragments. The length of the particles after grating may exceed 2 mm but shall not be greater than 5 mm. Mix the particles carefully and carry out the determination without delay.
7.3 In the case of seeds of medium size (groundnut, etc.), except for safflower seed, sunflower seed, soya beans and cottonseed with adherent linters, grind the test sample in the mechanical mill (5.2), which has previously been well cleaned, until the major dimension of the particles obtained is not greater than 2 mm. Reject the first particles (about one-twentieth of the sample). Collect the rest, mix carefully and carry out the determination without delay.
7.4 Small seeds (linseed, colza, hemp, etc.), as well as safflower seed, sunflower seed, soya beans and cottonseed with adherent linters, are analysed without previous grinding.
8.2 Determination
Place the vessel containing the test portion, with the lid removed, in the oven (see 5.5) set at 103 °C ± 2 °C. Close the oven. After 3 h (12 h to 16 h in the case of cottonseed with adherent linters), reckoned from the time when the temperature returns to 103 °C, open the oven. Immediately close the vessel with its lid and place it in the desiccator. As soon as the vessel has cooled to laboratory temperature, weigh it to the nearest 0,001 g. Return the vessel, with the lid removed, to the oven. After 1 h, repeat the operations of closing the vessel, allowing it to cool and weighing it. If the difference between the two weighings is equal to or less than 0,005 g (for a 5 g test portion), regard the determination as finished. If not, subject the test portion to successive 1 h periods in the oven, until the difference between two successive weighings is equal to or less than 0,005 g. Never put moist products in the oven together with products that are nearly dry, as this will result in the latter being partially rehydrated. Carry out two determinations on the same test sample.