GB/T 14454.7-2008Fragrance/Flavor substances -- Determination of freezing point (English PDF)

7.1 Determination of freezing point

7.1.1 Preparation of test sample

According to the requirements of GB/T 14454.1.

7.1.2 Preliminary test

If necessary, first melt the sample warmly. COOL a few milliliters of the sample to be tested in the test tube (6.2); USE a stirrer to stir until it freezes.

Write down the temperature at this time; KEEP in a cold place.

7.1.3 Determination of freezing point

In order to achieve a temperature requirement that is 5 °C lower than the temperature observed in the preliminary test, add water, melting ice, or any suitable mixed refrigerant to the wide-mouth bottle (see 6.4). Install the thick- walled test tube (6.3).

ADD 10 mL of sample (melt if necessary) to the test tube (6.2). INSERT the thermometer and carefully cool the sample to the temperature obtained in the preliminary test. Immediately insert the test tube (6.2) into the thick-walled test tube (6.3), to reduce the temperature by another 2 °C.

If necessary, a small amount of solid sample, obtained from the preliminary test, may be added to the sample as a seed crystal. USE a stirrer to continuously stir, to cause the sample to crystallize. When the temperature rises, stop stirring.

TAKE care to prevent the precipitated particles from adhering to the tube wall.

Carefully observe the temperature changes.

When the temperature on the temperature-time curve shows the maximum value, or remains unchanged at least 1 min, note the observed temperature.

REMOVE the test tube (6.2) from the device; re-liquefy the sample. REPEAT the determination, until the difference between the two consecutive test results does not exceed 0.2 °C.

TAKE the average of the last two readings as the final value.

Note 1: When determining the freezing point of individual products, when the temperature starts to rise, the stirring shall still be continued and shall not be stopped. Otherwise, the freezing point will be low, such as benzyl benzoate, which will be pointed out in the product standard for the fragrance/flavor substance concerned.

REMOVE the test tube (6.2) and stir in hot water3). After the sample melts, insert the test tube (6.2) into the thick-walled test tube (6.3); PLACE the thick-walled test tube (6.3) in a wide-mouth bottle (see 6.4). The bottle contains water that is 5 °C~10 °C below the expected freezing point. When cooling to some microcrystals in the test tube (6.2), or when it has cooled to the expected freezing point, the stirring is accelerated, to rapidly solidify. RECORD the temperature that rises to the highest point.

REMOVE the test tube (6.2) from the device; re-liquefy the sample. REPEAT the determination, until the difference between the two consecutive test results does not exceed 0.1 °C.

7.3.2 Samples with cineol content below 50%

Respectively, accurately weigh 5 g±0.001 g of the sample dried with anhydrous sodium sulfate and of cineol (5.3); and, mix in a conical flask (6.6). WEIGH 2.1 g±0.001 g of o-Cresol (5.1) and 3 g±0.001 g of the above mixed sample;

determine the freezing point according to 7.3.1.

8.1 Freezing point

The highest temperature observed at the end of the test is the freezing point, expressed in °C. It is accurate to 0.1 °C.

The tolerance of the parallel test results is 0.2 °C.

8.2 Safrole content

After the freezing point is measured, according to Table 1, it is converted into the content of safrole.

The tolerance of the parallel test results is 1%.

8.3 Cineol content

8.3.1 For samples with cineol content above 50%, after measuring the freezing

point, according to Table 2, convert to the content of cineol.

3) When melting with hot water, the water temperature must not be higher than its freezing point by 10 °C~15 °C. It shall also pay attention to prevent moisture intrusion.

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