Views: 0 Author: Site Editor Publish Time: 2022-02-07 Origin: Site
1. Oven method
: A sample of a certain quality is dried at a certain temperature under normal pressure for a certain period of time, and the solid content is expressed as the percentage of the weight of the sample after heating and the weight of the sample before heating.
2. Determination of step poly
① Take three weighing bottles, dry them in an oven at (105±2) ℃ for 1.5 hours, cool them in a desiccator for 30 minutes, and weigh them, and record them as m1.
② Weigh 1～2g (accurate to 0.0001g) of the sample into the dried weighing bottle, and mark it as m.
③ Gently transfer to the weighing bottle, so that the samples are evenly distributed at the bottom of the weighing bottle, slightly open the weighing bottle cap, place it in an oven at (105±2) ℃, turn on the blower, and dry the bottle for 3 hours. Cover tightly, put it in a desiccator to cool for 30min, weigh it, and record it as m2.
3. Calculation of results
The solid content of the sample is calculated in mass fraction X, and the value is expressed in (%), which is calculated according to formula (1):
In the formula:
m——the value of the sample mass. The unit is grams (g);
m1——the value of the sample mass. The unit is grams (g);
m2——the value of the mass of the weighing bottle and the sample after drying. The unit is grams (g).
Take the arithmetic mean of the two parallel determinations, and round it to 0.1% according to GB/T8170-2008, which is the determination result, and the difference between the two parallel determination results is not more than 0.3%.
2. Brix meter method
The sugar content of the solution measured by the principle of refraction has a certain proportional relationship with its solid content. By measuring the sugar content of the solution, the solid content of the sample can be converted according to a certain proportional coefficient.
2. Measurement steps:
The test should be carried out at room temperature, and the sample should be equilibrated to room temperature before measurement.
① Clean the surface of the prism of the sugar meter, drop about 0.3 mL of water on the surface, and adjust the zero according to the operation manual of the sugar meter.
② Discard the water on the Brix meter, wipe the prism dry, drop about 0.3 mL of sample on its surface, measure the Brix of the sample according to the operation manual of the Brix meter, until the two readings before and after are stable, record it as the sample Brix A.
③ Calculate the solid content of the sample according to the proportional coefficient n between the solid content and the sugar content obtained by data accumulation.
Note: Since this method is tested using the principle of refraction, do not use it for the test of samples that are difficult to wash with water, otherwise the prism surface will be contaminated and the test will be inaccurate.
3. Calculation of results
The solid content of the sample is measured in mass fraction X, and the value is expressed in (%), which is calculated according to formula (2):
X = n×A ---------- (2)
n——Conversion coefficient of solid content and sugar content
A——Brix of the sample, %