This standard specifies the instruments and utensils, sample preparation, determination method and result calculation method for the determination of powder and broken tea content in tea. This standard is applicable to the determination of powder and broken tea content in various types of tea. GB/T 8311-2002 Determination of tea powder and broken tea content GB/T8311-2002 standard download decompression password: www.bzxz.net

GB/T 8311---2002
This standard is a revision of GB/T83111987 "Determination of tea powder and broken tea content". The main differences between this standard and GB/T8311-1987 are: 1. "Chapter 1 Scope" and "Chapter 2 Reference Standards" are added; 2. "Chapter 1 Principle" in the original standard is changed to "Chapter 3 Definition"; 3. "Chapter 3 Operation Method" in the original standard is changed to "Chapter 5 Sample Preparation and Chapter 6 Determination Method", and the provisions of "5.1 Sampling" and "5.2 Sampling" are added;
4. *7.4 "Rectification method" is added. This standard shall replace GB/T8311-1987 from the date of implementation. This standard is proposed by the All-China Federation of Supply and Marketing Cooperatives. This standard is under the jurisdiction of the Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives. The drafting unit of this standard is the Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives. The main drafters of this standard are Zhao Yuxiang and Xiao Juqin. This standard is interpreted by the Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives. 140
1 Scope
National Standard of the People's Republic of China
Determination of dust and broken tea content
Tea --- Determination of dust and broken tea contentGB/T 8311—2002
Replaces GB/T83111987
This standard specifies the instruments and utensils, sample preparation, determination methods and result calculation methods for the determination of powder and broken tea content in tea. This standard is applicable to the determination of powder and broken tea content in various types of tea. 2 Cited standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T8170—1987 Rules for rounding off values
GB/T8302—2002 Tea sampling
3 Definitions
This standard adopts the following definitions.
Dust and broken tea According to certain operating procedures, use the specified speed and aperture sieve to sieve out the undersize in various tea samples. 4 Instruments and utensils
4.1 Sample divider and sample plate or sample plate (with notches on the two diagonal corners of the plate). 4.2 Electric screening machine
4.2.1 Speed ​​200r/min, swing amplitude 50mm (for raw tea). 4.2.2 Speed ​​200r/min, swing amplitude 60mm (for fine tea). 4.3 Inspection sieve: copper wire woven square hole standard sieve, with sieve bottom and sieve cover. 4.3.1 Raw tea powder sieve: sieve diameter 280mm. a) Aperture 1.25 mm;
b) Aperture 1.12mm.
4.3.2 Refined tea powder and broken tea sieve: sieve diameter 200mm. 4.3.2.1 Powder sieve
a) Aperture 0.63mm (for strips and round tea); b) Aperture 0.45mm (for broken and coarse tea); c) Aperture 0.23mm (for flake tea); d) Aperture 0.18mm (for powdered tea). 4.3.2.2 Broken tea sieve
a) Aperture 1.25mm (for strips and round tea); Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on June 17, 2002, implemented on December 1, 2002
b) Aperture 1.60mm (for coarse tea). Note
GB/T 8311—2002
! Strip and round tea refer to Gongfu black tea, Xiaozhong black tea, leaf tea in broken black tea, Zhenmei, Gongxi, pearl tea, rain tea and scented tea. 2 Coarse tea refers to Tieguanyin, Color, Oolong, Narcissus, Qizhong, White Peony, Gongmei and Puer loose tea. 5 Sample preparation
5.1 SamplingwwW.bzxz.Net
Sampling shall be carried out in accordance with the provisions of GB/T8302.
5.2 Sampling
Sampling can be carried out by quartering method or sample divider.
5.2.1 Quartering method: Place the sample in the sample dividing tray and pour it back and forth. Each time the sample is poured, it should be evenly sprinkled in the tray to form a sample pile with basically equal width and height. Divide the tea pile crosswise, take two diagonal piles of samples, and mix them thoroughly to form two samples. 5.2.2 Sampling by sample divider: Pour the sample evenly into the sample divider so that its thickness is basically uniform and does not exceed the edge of the sample divider. Open the partition to allow the tea sample to naturally fall into the tea receivers on both sides through the multi-grid dividing slots. 6 Determination method
6.1 Raw tea
Weigh 100g (accurate to 0.1g) of the fully mixed sample, pour it onto the 1.25mm mesh, put on the 1.12mm mesh, cover the sieve cover, put on the sieve bottom, press the start button, and sieve for 150 turns. After the machine stops automatically, take the sieve under the 1.12mm mesh and weigh it (accurate to 0.1g), which is the content of broken tea.
6.2 Refined tea
6.2.1 Strip, round tea: Weigh 100g of the thoroughly mixed sample (accurate to 0.1g), pour it into the specified broken tea sieve and powder sieve test set sieve, cover the sieve cover, press the start button, and sieve for 100 turns. Weigh the sieve under the powder sieve (accurate to 0.1g), which is the powder content. Remove the sieve on the broken tea sieve, and then pour the broken tea on the sieve surface of the powder sieve back into the broken tea sieve connected to the bottom of the sieve, cover the sieve cover, put it on the electric sieving machine, and sieve for 50 turns. Weigh the sieve under the sieve (accurate to 0.1g), which is the broken tea content. 6.2.2 Coarse tea: Weigh 100g of the thoroughly mixed sample (accurate to 0.1g), pour it into the specified broken tea sieve and powder sieve test set sieve, cover the sieve cover, and sieve for 100 turns. Weigh the powder sieve (accurate to 0.1g) to get the powder content. Then weigh the broken tea on the powder sieve (accurate to 0.1g) to get the broken tea content. 6.2.3 Broken, sliced ​​and powdered tea: Weigh 100g of the fully mixed sample (accurate to 0.1g), pour it into the specified powder sieve, and sieve it for 100 turns. Weigh the powder sieve (accurate to 0.1g) to get the powder content. 7 Calculation of results
7.1 Calculation formula
The content of tea powder is calculated according to formula (1): Broken tea (%)
The content of tea powder is calculated according to formula (2): Powder (%)
The content of tea broken tea is calculated according to formula (3): Wherein: M.--mass of broken tea under the sieve·g; mass of powder under the sieve, g;
Broken tea (%) =
Ma×100
（1）
（2）
（3）
Ms-mass of broken tea under the sieve, g;
M—mass of sample, g.
7.2 Repeatability
GB/T 8311---2002
7.2.1 When the measured value is less than or equal to 3%, the difference between the two measured values ​​of the same sample shall not exceed 0.2%; if it exceeds, re-sampling and testing is required.
When the measured value is greater than 3% and less than or equal to 5%, the difference between the two measured values ​​of the same sample shall not exceed 0.3%, otherwise, re-sampling and testing is required.
7.2.3 When the measured value is greater than 5%, the difference between the two measured values ​​of the same sample shall not exceed 0.5%, otherwise, re-sampling and testing is required. 7.3 Average value calculation
Average the two measured values ​​that do not exceed the error range, and then round them to one decimal place according to the numerical rounding rules, which is the actual broken tea, powder or broken tea content of the sample.
7.4 Rounding method
Perform in accordance with the provisions of GB/T8170.
8 Test Report
The test report shall include the following contents:
a) the method used;
b) the measurement results;
c) operations not specified in this standard or additional operations;
d) the name and number of the specimen;
e) the test date and the inspector.
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