GB/T 5494-2026 Inspection of grain and oils—Determination of impurities and defective kernels in grains and oilseeds English, Anglais, Englisch, Inglés, えいご
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ICS 13.220.10
CCS H 57
National Standard of the People's Republic of China
GB/T 5494-2026
Replaces GB/T 5494-2019
Inspection of grain and oils - Determination of impurities and defective kernels in grains and oilseeds
粮油检验 粮食、油料的杂质、不完善粒检验
Issue date: 2026-01-28 Implementation date: 2027-02-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Sensory Inspection Method
5 Instrumental Inspection Method
Appendix A (Normative) Specifications of Sieve Layers for Sample Sieving
Inspection of Grain and Oils — Determination of Impurities and Unsound Kernels in Grains and Oilseeds
1 Scope
This document describes the methods for determining the content of impurities, unsound kernels in grains and oilseeds, and the content of paddy kernels in husked rice.
The sensory inspection method in this document applies to the determination of impurities, unsound kernels in grains and oilseeds, and the content of paddy kernels in husked rice. The instrumental inspection method applies to the determination of unsound kernels in grains and oilseeds and the content of paddy kernels in husked rice.
2 Normative References
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 5490 Inspection of grain and oils – General rules
GB/T 5491 Inspection of grain and oilseeds – Methods for sampling and sample division
GB/T 22505 Inspection of grain and oils – Lighting requirements for sensory analysis environment
GB/T 36091 Grain and oil machinery – Test sieve for grain inspection
LS/T 3545 Grain and oil machinery – Divider for inspection
LS/T 6402 Inspection of grain and oils – General principles for validation of fitness for purpose and evaluation of results of equipment and method standards
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 5490 and the following apply.
3.1
large sample
A sample taken from the laboratory sample, used for sieving to separate large impurities on the upper sieve and the material passing through the lower sieve.
3.2
impurities from large samples
A collective term for the large impurities retained on the upper sieve and the material passing through the lower sieve obtained during the sieving of the large sample.
3.3
small sample
A sample taken from the material after the inspection of impurities from the large sample, used for determining impurities similar in size to grains, paddy kernels in husked rice, unsound kernels, etc.
3.4
impurities from small samples
A collective term for impurities picked out from the small sample according to the provisions of the product standard.
4 Sensory Inspection Method
4.1 Apparatus
4.1.1 Balance: Sensitivity 0.01 g, 0.1 g.
4.1.2 Grain test sieves: Complying with the requirements of GB/T 36091.
4.1.3 Electric sieve shaker: Rotates clockwise and counterclockwise for 1 minute each, speed 110 r/min ~ 120 r/min.
.1.4 Sample divider: Complying with the requirements of LS/T 3545.
4.1.5 Hulling/shelling equipment: Causes no damage to the kernels, rice, etc. after hulling (e.g., peanut kernels, brown rice).
4.1.6 Sample dividing spatula (or riffle divider).
4.1.7 Analysis tray/pan.
4.1.8 Forceps/tweezers.
4.2 Lighting Requirements
The operation shall be carried out under scattered daylight or under a standard light source conforming to GB/T 22505.
4.3 Sample Preparation
Divide the test sample according to the provisions of GB/T 5491 to the mass specified in Table 1 or Table 2. For grain and oilseed varieties where the test sample mass is not specified, refer to the test sample mass of varieties with similar shape and size.
4.4 Operating Procedure
4.4.1 Determination of Impurities and Unsound Kernels in Grains and Oilseeds (excluding rice products)
4.4.1.1 Sieving Method
4.4.1.1.1 Electric Sieve Shaker Method
Assemble the layers of the grain test sieves (4.1.2) according to Appendix A (coarser sieve on top, finer sieve below, with bottom pan attached). Place the test sample onto the top sieve, and cover with the sieve lid. Place the sieve stack on the electric sieve shaker (4.1.3), connect the power, turn on the switch. The shaker will automatically sieve for 1 minute clockwise and 1 minute counterclockwise. After sieving, let it stand for a moment, then remove the lid. Particles wedged in the sieve openings are considered part of the oversize fraction.
4.4.1.1.2 Manual Sieving Method
Assemble the sieve layers as described in 4.4.1.1.1, pour in the test sample, and cover with the lid. Place the sieve stack on a glass plate or smooth tabletop. Using both hands, sieve for 1 minute clockwise and 1 minute counterclockwise at a speed of 110 r/min ~ 120 r/min. The sieving motion should cover an amplitude approximately 8 cm ~ 10 cm beyond the diameter of the sieve. Post-sieving operations are the same as in 4.4.1.1.1.
4.4.1.2 Determination of Impurities Content from Large Sample
Take a test sample portion according to 4.3, to the large sample mass (m) specified in Table 1, accurate to 0.1 g. Sieve using the method specified in 4.4.1.1.1 or 4.4.1.1.2, performing the sieving twice (for very large grains/oilseeds, sieve four times). Then, pick out the large impurities from the upper sieve(s) and combine them with the material collected in the bottom pan (sieved material). Weigh this combined material (m₁), accurate to 0.01 g, and calculate according to formula (1). If any grain kernels adhere to the large impurities, those kernels should be returned to the large sample. For example, maize cobs should have the kernels removed and then the cob is classified as impurity.
For paddy (rough rice) samples, add a 1.5 mm diameter round-hole sieve below the 2.0 mm diameter round-hole sieve. Take a test sample portion according to 4.3, to the large sample mass (m) specified in Table 1, accurate to 0.1 g. Sieve using the method specified in 4.4.1.1.1 or 4.4.1.1.2, performing the sieving twice. Then, pick out the large impurities from the 2.0 mm sieve. Pick out the whole paddy kernels and whole paddy kernels in husked rice retained on the 1.5 mm sieve and return them to the rice/paddy sample from the 2.0 mm sieve. Combine the material passing through the 1.5 mm sieve (bottom pan) and any other material retained on the 1.5 mm sieve (excluding the returned kernels) with the large impurities from the 2.0 mm sieve. Weigh this combined material (m₁), accurate to 0.01 g, and calculate according to formula (1).
4.4.1.3 Determination of Impurities Content from Small Sample
From the material that has been inspected for large sample impurities, take a test sample portion according to 4.3, to the small sample mass (m₂) specified in Table 1, accurate to 0.01 g. Pour onto the analysis tray. Pick out the impurities according to the provisions of the product standard, and weigh them (m₃), accurate to 0.01 g. Calculate according to formula (2).
4.4.1.4 Determination of Inorganic Impurities Content
From the impurities picked out from the small sample (m₃), pick out the inorganic impurities and weigh them (m₄), accurate to 0.01 g. Calculate according to formula (4).
Note 1: The determination of mineral matter content refers to this inorganic impurities content determination.
Note 2: The inorganic impurity content specified in product standards for grains and oilseeds (excluding rice products) specifically refers to the inorganic impurity content found in the small sample.
4.4.1.5 Determination of Unsound Kernels Content
4.4.1.5.1 Grains/Oilseeds Not Requiring Hulling/Shelling
While inspecting the small sample impurities (4.4.1.3), pick out the various types of unsound kernels according to the provisions of the product standard and weigh them (mₙ), accurate to 0.01 g. Calculate according to formula (5) or formula (7).
4.4.1.5.2 Grains/Oilseeds Requiring Hulling/Shelling (e.g., Paddy, Groundnuts in shell)
Weigh the clean sample (m₅) remaining after the small sample impurity inspection (4.4.1.3). First, pick out sprouted kernels and hull/shell them separately by hand. Then, hull/shell the remaining sample using hulling/shelling equipment or by hand. Pick out the various types of unsound kernels according to the provisions of the product standard from the hulled/shelled material. Combine these with the previously separated and hulled/shelled sprouted kernels. Weigh the total unsound kernels (mⱼ), accurate to 0.01 g. Calculate according to formula (6) or formula (8).
4.4.2 Determination of Impurities and Unsound Kernels in Rice Products
4.4.2.1 Determination of Sieved Material (Bran Powder) Content
