Determination of Tea Fibers with Crude Fiber Tester

Regarding the determination of crude fiber content in tea, we have a lot of standards to specify. Because tea is a common drink for people, it plays a different role on various occasions. Therefore, the nutrient components in tea are also the focus of attention. For example, the content of crude fiber in tea leaves is an essential parameter in tea testing. In addition, fat content is occasionally used. The two parameters, respectively, can be done with a coarse fiber analyzer and a crude fat analyzer. The principle of the crude fiber analyzer is to digest the sample by acid-alkali digestion and determine the weight, while the crude fat analyzer The fat content was determined by gravimetric method according to the Soxhlet extraction principle.

Here we analyze how to measure the crude fiber content in tea using a fiber tester.

1. Principle: The tea sample is digested with dilute sulfuric acid solution, and the residue is filtered and washed. The sample is then dissolved with sodium hydroxide and all of the material in the sample that is fully soluble in the alkali is dissolved in the solution, then filtered, washed, dried, weighed, and finally left in the residue. At this point, the residue was burned at a high temperature, and after ashing, the weight loss after the ashing was measured.

2. Reagents and instruments: 0.255 mol/l (12.5 g/l) sulfuric acid solution; 0.313 mol/l (12.5 g/l) sodium hydroxide solution; hydrochloric acid (10 g/l) solution; ethanol; ether. Analytical balance; Crude fiber tester; Filter; Oldham's crucible; High temperature electric furnace; Electric heated blast oven.

3. Procedure: a. Weigh 2.5 g of tea sample to the nearest 0.001 g. b. Place the sample in the flask of the fiber analyzer and attach the condenser. Press the button on the panel of the fiber tester, the instrument starts to add acid and heat to dissolve all the substances that can be dissolved by the acid in the sample. Then filter and clean the sample. c. Continue pressing the buttons on the operation panel to alkalize the sample. The basic procedure is the same as b, the added solution is changed from acid to alkali. d. The residue was washed with ethanol and diethyl ether, and the remaining solvent was removed by vacuum suction filtration. Then put it in (103 ~ 105) °C oven bake 4 h, let cool in the desiccator to room temperature and weigh. Then bake for 1 h each time under the same conditions. Until two consecutive weighings do not differ by more than 0.001 g. Record the lowest weighing to the nearest 0.001 g. e. Ashing: The sample is placed in a high temperature electric furnace (525 ± 25 °C) and is burned for 2 hours. If the weight is less than 0.001 g after the last two burning conditions are the same, stop burning. Weigh, take the minimum weight.