GB/T 8310-2002 Determination of crude fiber in tea

This standard specifies the principle, instruments and utensils, reagents and solutions, operation methods and result calculation methods for the determination of crude fiber in tea. This standard is applicable to the determination of crude fiber content in tea. GB/T 8310-2002 Determination of crude fiber in tea GB/T8310-2002 Standard download decompression password: www.bzxz.net

GB/T8310—2002
This standard is a revision of GB/T8310—1987 "Determination of Crude Fiber in Tea".
The main differences between this standard and GB/T8310-1987 are: glass sand core crucibles are used instead of asbestos crucibles, nylon cloth filtration is used instead of nylon cloth suction filtration, and acetone is used instead of ether. This standard will replace GB/T8310—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: Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives. The main drafters of this standard: Zhou Weilong, Sun Anhua, Zhong Luo. The Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives is responsible for the interpretation of this standard. 137
1 Scope
National Standard of the People's Republic of China
Tea - Determination of crude fibre content
Tea - Determination of crude fibre contentGB/T8310—2002
Replaces GB/T8310--1987
This standard specifies the principle, instruments and utensils, reagents and solutions, operation methods and result calculation methods for the determination of crude fibre in tea. This standard is applicable to the determination of crude fibre content in tea. 2 Referenced Standards
The provisions contained in the following references constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. G/T8302-2002 Tea sampling
GB3/T8303--2002 Preparation of ground tea sample and determination of dry matter content 3 Principle
The sample is digested with acid and alkali of certain concentration, and the residue left is then ashed and weighed. The crude fiber content is calculated from the mass loss during ashing.
Instruments and appliances
Conventional laboratory instruments and the following items:
4.1 Analytical balance: sensitivity 0.001g.
4.2 Nylon cloth: pore size 50μm (equivalent to 300 μm). 4.3 Glass sand core plug: average micropore diameter 80um-160um, volume 30mL. 4.4 High temperature furnace: 525℃±25℃.
4.5 Blast electric heating constant temperature drying oven: temperature control 120℃2C. 4.6 Dryer: Contain effective desiccant.
5 Reagents and solutions
The reagents used should be analytical grade (AR). Water is distilled water. 5.1 Sulfuric acid: 1.25% solution.
5.2 Sodium hydroxide: 1.25% solution.
5.3 Hydrochloric acid: 1% solution.
5.4 95% ethanol.
5.5 Acetone.
6 Operation method
6-1 Sampling
Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on 2002~06-17 138
Implemented on 2002-12-01
According to the provisions of GB/T8302.
6.2 Sample preparation
According to the provisions of GB/T8303. bzxZ.net
6.3 Determination steps
6.3.1 Acid digestion
GB/T 8310—2002
Weigh about 2.5g (accurate to 0.001g) of the sample (6.2) into a 400mL beaker, add 200ml of 1.25% sulfuric acid solution (5.1) at about 100C, and heat on an electric stove (boil within 1min). Slightly boil for 30min, and add hot water at any time to maintain the original volume of the solution. Remove the heat source, pour the acid digestion solution into a Buchner funnel with 50um nylon cloth (4.2) inside, slowly pump out the air and filter under reduced pressure, and wash the residue with 50ml of boiling distilled water each time until it is neutral, which should be completed within 10min. 6.3.2 Alkaline digestion
Use 200mL of 1.25% sodium hydroxide (5.2) at about 100°C to wash all the residues on the nylon cloth into the original beaker, and heat it on an electric stove (boil within 1 minute). Boil slightly for 30 minutes? And add hot water at any time to maintain the volume of the original solution. Pour the alkaline digestion solution and the residue into a glass sand core crucible (4.3) connected to a suction filtration bottle, slowly pump air to reduce pressure, wash the residue with about 50ml of boiling distilled water, wash it once with 1% hydrochloric acid (5.3), and then wash it several times with boiling water until it is neutral, and finally wash it twice with ethanol (5.4) and three times with acetone. Filter it to dryness and remove the solvent.
6.3.3 Drying
Move the above crucible and residue into a drying oven (4.5) and dry it at 120°C for 4 hours. Place in a dryer (4.6) to cool, and weigh (accurate to 0.001 g).
6.3.4 Ashing
Put the weighed crucible in a high temperature furnace (4.4) and ash at 525°C ± 25°C for 2 h. When the furnace temperature drops to about 300°C, take it out and cool it in a dryer (4.6), and weigh it (accurate to 0.001 g). 7 Result calculation
7.1 Calculation method
The crude fiber content in tea leaves is expressed as dry mass fraction, and is calculated according to formula (1): 100(M, -- M2)
Crude fiber (%)-1
Where: M.---mass of sample.g;
M, ...mass of crucible and residue before ashing.g; M-mass of ash and ash after ashing g,
mDry matter content of sample, %.
If the repeatability requirement (7.2) is met, the arithmetic mean of the two measurements shall be taken as the result, and the result shall be rounded to one decimal place. 7.2 Repeatability
The difference between the two measured values ​​of the sample shall not exceed 0.5 per 100g of sample. (1)
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