Determination of tea powder and broken tea

national standards of People's Republic of China

Determination of the content of tea powder and broken tea GB 8311-87

Tea―Determination of dust and broken tea content
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This standard applies to the determination of tea powder and broken tea content.
The powder and broken tea are sieved through a prescribed aperture sieve.
1 Principle According to a certain operating procedure, sieve and sieve out the powder and broken tea in various tea samples with the specified sieve.
2 Instruments and supplies
2.1 Sampler and sample board.
2.2 Electric screening machine.
2.2.1 Speed ​​200r/min, Swivel amplitude 25mm (for wool tea).
2.2.2 Rotation speed 200r/min, swivel amplitude 60mm (for refined tea).
2.3 Inspection screen: Copper wire woven square hole standard screen with screen bottom and screen cover.
2.3.1 Maocha broken tea sieve, sieve diameter 280mm.
a. Aperture 1.25mm;
b. The aperture is 1.12mm.
2.3.2 refined tea powder broken tea sieve: sieve diameter 200mm.
2.3.2.1 Powder Sieve
a. Aperture 630μm (for bars, rounds and thick teas, see note);
b. Aperture 450μm (for Fragmented Tea);
c. Aperture 230μm (for sheet-shaped tea);
d. Aperture 180μm (used for tea-end tea).
2.3.2.2 Broken Tea Screen
a. Aperture 1.25mm (for bar, round tea);
b. Aperture 1.60mm (for rough tea).
Note: One, round tea system refers to the leaf tea in the black tea, black tea, red broken tea, Zhenmei, Gongxi, Zhucha,
Rain tea and flower tea.
2 Thick tea refers to Tieguanyin, color species, oolong, narcissus, exotic species, white peony, Gongmei, and Puju Loose Tea.
3 Operation method
3.1 Mao Mao After the sample is fully mixed and shrank, it is weighed to 100g (accurate to 0.1g), poured into an aperture of 1.25mm screen, the next set of aperture 1.12mm sieve, cover the screen cover, set the screen bottom, press Start button, sieve 150 r/min. After the automatic shutdown, take the screened material with an aperture of 1.12mm sieve and weigh (accurate to 0.01g), which is the broken tea content.
3.2 Refined tea
3.2.1 Article, round tea: After the sample is fully mixed and reduced, weigh 100g (accurate to 0.1g), pour into the test set sieve of the broken tea sieve and powder sieve, cover the sieve lid ,Press the start button and sieve 100 r/min. The undersize of the powder sieve was weighed (accurate to 0.01 g), which is the powder content. Remove the sifting material of the broken tea sieve, and then pour the broken tea on the sieve surface of the powder sieve into the broken tea sieve connected to the bottom of the sieve. Place the sieve cover on the sieve and place it on the electric screen. Operate at 50r/min. . Weigh the sieve
(accurate to 0.01g), which is broken tea content.
3.2.2 Coarse-shaped tea: After the sample to be tested is fully mixed and reduced, 100g (accurate to 0.1g) is weighed, poured into the test crate of the crushed tea sieve and the powder sieve, and covered with a sieve lid. Sifting 100 turns. Measure the undersize of the powder sieve (accurate to 0.01g),
That is, the powder content. The crushed tea on the powder sieve is weighed (accurate to 0.01g), which is the broken tea content.
3.2.3 Crushed, sliced, and shaped tea: Same as 3.1 sampling method. The weighed sample was poured into a prescribed powder sieve and sieved for 100 rotations.
The sieved material was weighed (accurate to 0.01 g), which is the powder content.
4 result calculation
4.1 Calculation Formula The percentage of tea powder content is calculated according to equation (1):
M1
Powder (%)=──×100 ................................(1)
M

The percentage of tea broken tea is calculated according to equation (2):
M2
Broken Tea (%)=──×100 .................................(2)
M

Where: M1 - sieve powder quality, g;
M2 - sieve broken tea quality, g;
M - sample mass, g.
4.2 Repeatability When the measured value is 3%, 3% to 5% and 5% or more, the difference between the two measured values ​​of the same sample shall not exceed 0.2%, 0.3% and 0.5%, respectively.
5 Results report The test report should include the following:
a. Method used;
b. the result of the determination;
c. The operations specified or added at the end of this standard;
d. The name and origin of the sample;
e. Test date, operator.

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Additional information:
This standard was proposed by the National Food Industry Standardization Technical Committee.
This standard was drafted by the Shanghai Import and Export Commodity Inspector, Zhejiang Tea Company, and the Ministry of Commerce's Tea Bureau.
The main drafters of this standard are Song Mengguang, Yang Fangkang, He Naiyun, Fei Rongya, Wang Jinxian, and Wang Liming.
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The Ministry of Commerce of the People's Republic of China approved 1988-07-01 for implementation in 1987-11-19

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