SN/T 0800.18-1999Cereals and feedstuffs for import and export. Method for the inspection of admixture (English PDF)

5.1 Instruments and utensils

5.1.1 Balance: sensitivity is 0.1g or 0.01g.

5.1.2 Electric screening machine.

5.1.3 Round hole screening sieves: sieve hole diameters are 1.0, 1.2, 1.5, 2.0, 3.0,

4.0mm, with sieve bottom and sieve cover.

5.1.4 Bran flour sieves: circular sieve diameter is 22.5cm; sieve hole diameter is 1.0mm;

total number of sieve holes is 3596 holes; with sieve bottom and sieve cover.

5.1.5 Tweezers, sample trays, small dishes, brushes, magnifying glasses, and so on.

5.2 Sieving

Put the required sieves on the sieve bottom plate in order of aperture from small to large.

Gently pour an appropriate amount of specimen into the center of the top sieve. Cover with a sieve lid.

5.2.1 Manual sieving

Place the round hole sieve on a glass plate or a smooth tabletop. Use both hands at a speed of (110~120) times per minute to sieve in clockwise and counterclockwise directions for 1min each. The sieving amplitude is (8~10) cm larger than the sieve diameter.

5.2.2 Machine sieving

Use an electric sieving machine with a rotating speed of (110~120) r/min; sieving amplitude is 1/2 radius of the selected sieve; sieve for 2min.

After sieving, gently remove the sieve. Pour the sieve into the sample plate. The material plugged in the sieve holes is combined into the over-sieve sample. Then, pour out the under-sieve in the sieve bottom plate. Use a brush to clean the dust adhering to the bottom plate. Merge into the under-sieve.

5.3 Inspection of harmful admixtures, large admixtures

5.3.1 Operation method

Take the average sample according to Chapter 4. The average sample size shall be determined according to SN/T 0800.1. After inspecting the appearance and taking the water, weigh it on the balance with resolution of 0.1g. Then place it on the sample plate.

According to the explanation in SN/T 0798, sort out harmful admixtures and large admixtures. Respectively weigh on the balance with resolution of 0.01g.

5.3.2 Result calculation

The percentages of large admixture content and harmful admixture content are calculated according to formula (1) and formula (2):

5.6.2 Inspection of grains of rice, unhulled tares, minerals, and grains of different

species

Prepare test specimens according to Chapter 4. The specimen size is determined according to Annex A. Weigh on the balance with resolution of 0.1g. Place it on a flat plate or sample tray. Use tweezers to sort out grains of rice, unhulled tares, minerals, and grains of different species separately. Weigh on the balance with resolution of 0.01g.

Calculate the percentages separately. Simultaneously count grains of rice, unhulled tares, minerals, and grains of different species.

5.6.3 Inspection of other admixtures

Prepare test specimens according to Chapter 4. The specimen size is determined according to Annex A. Weigh on the balance with resolution of 0.1g. Place it on a flat plate or sample tray. Pick out other admixtures. Weigh on the balance with resolution of 0.01g. Calculate the percentages.

5.6.4 Calculation of total admixtures

Calculate the percentage according to formula (6):

The total amount of admixtures (%) = bran flour (%) + minerals (%) + grains of rice, unhulled tares (%) + grains of different species (%) + other admixtures (%) …. (6)

The inspection result of the total amount of admixtures is rounded to one decimal place.

The results of the admixture sub-item shall be rounded to two decimal places.

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