ISO 4150-2011 pdf download.Green coffee or raw coffee – Size analysis – Manual and machine sieving.
7.1 Test portion
Weigh. to the nearest 0.1 g, 300 g of the laboratory sample.
7.2 Selection of sieves
Select a nest of sieves (5.2) with round apertures (5.3.1). Assemble the sieves in descending order of aperture size. If dealing with a sample of substantially peaberry coffee, to determine the percentage mass fraction of peaberry in the test portion, use a sieve with slotted openings (5.3.2).
Discard the sieves with larger apertures through which all beans can pass.
NOTE The common sieve numbers are 18, 17, 16, 15, 14 and 12.
Place the receiver (5.5) under the sieve with the smallest apertures.
7.3 Sieving and weighing
Pour the test portion (7.1) on to the upper sieve and put the lid (5.4) in place.
7.3.1 Manual sieving
7.3.1.1 Spread a clean, dry, soft cloth under the receiver, in order to obtain smooth sliding.
Spread the cloth (see 7.2) over a flat surface and then put the nest of sieves on it.
7.3.1.2 Agitate uniformly the nest of sieves for 3 mm, one way (back and forth) without raising it from the surface at a speed of between 110 cycles per mm and 130 cycles per mm with a displacement of 10 cm approximately.
NOTE A speed with 150 cycles per mm and 160 cycles per mm and a displacement of 5 cm can be used.
If using slotted aperture sieves, agitate in a direction parallel to the length of apertures. Beans remaining in apertures shall be considered to be retained on the sieve in question.
Remove all the beans from each sieve separately, to avoid loss of the beans. Put the lid on the top of the respective sieve, then put one hand under the sieve and push the beans up. Then, carefully place the beans on a tray.
7.3.1.3 Weigh to the nearest 0,1 g, the beans collected on each of the sieves used and in the receiver.
7.3.2 Machine sieving
7.3.2.1 Put the nest of sieves on the machine (5.6) firmly, and turn the equipment on for 3 mi If using slotted aperture sieves, agitate in a direction parallel with the length of apertures. Beans remaining in apertures shall be considered to be retained on the sieve in question.
7.3.2.2 Remove all the beans from each sieve separately, to avoid loss of the beans. Put the lid on the top of the respective sieve, then put one hand under the sieve and push the beans up. Then, carefully place the beans on a tray.
7.3.2.3 Weigh to the nearest 0,1 g, the beans collected on each of the sieves used and in the receiver.
7.4 Additional observations
Note whether any of the fractions contains a significant proportion of foreign matter, bean fragments or broken beans. In this case, apply ISO 4149.ISO 4150 pdf download.