ISO 7970:2021 pdf download – Wheat (Triticum aestivum L.)一Specification.
C.4 Procedure
C.4.1 General See Figure C.1.
11 a grain exhibits several defects, It shall be classified in the category with the lowest maximum permissible level (see Table 1).
Any components that become stuck in the apertures of a sieve shall be considered as being retained by the sieve.
(.4.2 Preparation of test sample
Reduce the laboratory sample by using a divider C.2.2) until a quantity of approximately 1 000 g Is obtained,
Weigh, to the nearest I g. the test sample so obtained and place it in the container c.2S).
During the preparation of the test sample, note whether any particular odour foreign to that of wheat Is detected, whether any living insects (specified In Annex B) arc present or other anomalies.
C.4.3 Determination of ergot
Separate ergot from the test sample (see CA.2). put it in a dish (C2A) and weigh it to the nearest 0,01 g. C4.4 First division
Divide the sample from which the ergot has been removed by using the divider (C2.2) until a quantity of approximately 250 g is obtained,
Weigh, to the nearest 0,01 g, the test portion so obtained. If any husked grains are observed, separate them from their envelopes before the first sieving.
(.4.5 First sieving
Fit together the 3,55 mm sieve, the 1,00 mm sieve and the receiver, so that the sieve apertures are positioned parallel to each other.
Place the test portion (see CA4) on the 3.55 mm sieve and put on the lid.
Shake manually for 45 s with a forwards-and-backwards motion in the direction of the apertures of the sieve, keeping the sieve In a horizontal plane.
From the material that did not pass through the 3,55 mm sieve. separate, by placing in separate dishes (LZA). the other cereals, the organic and Inorganic components of the extraneous matter, harmful and/ or toxic seeds, Fusarium-contaminated grains, rotten grains, bunted grains and black point grains, and any wheat grains that should have been retained. Wheat grains retained shall then he added to the material that does not pass through the 1.00 mm sieve Add the Inorganic elements of the extraneous matter to the material that has passed through the 1,00 mm sieve. Weigh the fractions thus obtained to the nearest 0,01g.
C.4.6 Second divisIon
Thoroughly mix the fraction retained between the 1.00 mm sieve and the 3.55 mm sieve. Then add the wheat grains retained on the 3,55 mm sieve, and divide it using the divider (Cl.2) until approximately 60 g is obtained. Weigh to the nearest 0.01 g the portion thus obtained.
Spread out the portion, then separate and classify It by placing in the dishes the broken grains, other cereaLs, organic and inorganic extraneous matter, unsound grains, grains attacked by pests, harmful and/or toxic seeds, bunted grains, Fusariuni-contaminated grains, rotten grains, immature grains and black point grains. Weigh each fraction to the nearest 0.01 g.
Verify that the sum of impurities plus wheat is equal to the mass of the portion with a tolerance of O,5%.
C.4.7 Second sieving
Pour the portion from which the impurities specified in CA.6 were removed onto the 1.70 mm sieve fitted with a receiver and put on the lid.
Shake manually for 45 s with a Iorwards-and-backwards motion in the direction of the apertures of the sieve, keeping the sieve in the horizontal plane.
Weigh, to the nearest 0,01 g, the undersize grain thus obtained that corresponds to the shrivelled grains.
C.4.8 Number of determinations
Repeat the determination on the same test sample, using another Lest portion obtained as specified InCA.4.
C.5 Expression of results
Express the content of each category of impurity, using Formulae (C.1) to (C.3). as a percentage mass fraction of the grains as received,