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This standard replaces GB/T 9696-2008 Animal and Vegetable Fats and Oils—Determination of Moisture and Volatile Matter Content and GB/T 5528-2008 Animal and Vegetable Fats and Oils—Determination of Moisture and Volatile Matter Content.
This standard has the following main changes with regards to GB/T 9696-2008 and GB/T 5528-2008:
——The standard name was changed to “National Food Safety Standard—Animal and Vegetable Fats and Oils—Determination of Moisture and Volatile Matter";
——This standard combines methods in GB/T 9696-2008 and GB/T 5528-2008.
National Food Safety Standard
Animal and Vegetable Fats and Oils
Determination of Moisture and Volatile Matter
1 Scope
This standard specifies two methods for determination of moisture and volatile matter in animal and vegetable fats and oils.
The first method of this standard [Sand Bath (Electric Heating Plate) Method] applies to all animal and vegetable fats and oils; the second method (Electrically Heated Drying Oven Method) is only applicable to non-dry fats and oils with acid value less than 4mg/g, not applicable to lauric acid type oil (palm kernel oil and coconut oil).
Method I Sand Bath (Electric Heating Plate) Method
2 Principle
Under the conditions of 103 ± 2℃, the test sample is heated until moisture and volatile matter are completely dispersed and then determine the mass loss of the sample.
3 Apparatus
3.1 Analytical balance: sensitivity of 0.001g.
3.2 Dish: made of ceramic or glass flat bottom dish, in diameter of 80mm/90mm, with depth of about 30mm.
3.3 Thermometer: graduated range is at least 80°C~110°C, with length of about 100mm, mercury ball reinforced and expansion chamber at the upper end.
3.4 Sand bath or electric hot plate (room temperature~150°C).
3.5 Dryer: contains an effective desiccant.
4 Analytical Procedures
4.1 Preparation of samples
Weigh about 20g of sample in the pre-dried dish which is weighed together with a thermometer, accurate to 0.001g.
Liquid samples: For liquid sample which is clear and has no precipitate, shake it in a closed vessel to make it uniform. For liquid sample with a turbidity or a precipitate, shake it in a closed vessel until the precipitate is completely separated from the vessel wall, and evenly distributed in the oils. Check whether the precipitates is on the walls of the vessel. If it is, remove them completely (open the vessel if necessary) so that they are mixed thoroughly with the oil.
Solid sample: Heat the sample until it just becomes liquid, operate as a liquid sample and mix it thoroughly.
4.2 Sample determination
The dish containing the test sample is heated to 90℃ in a sand bath or electric hot plate, with temperature rise rate controlled at about 10℃/min and stir with a thermometer while heating.
Reduce the heating rate, observe the rise of the bubble at the bottom of the dish. Control the temperature rise to 103℃±2℃ and ensure that it does not exceed 105℃. Continue to stir until the bottom of the dish is free of air bubbles.
To ensure the water is fully dispersed, repeat several times of the step, i.e. heating to 103℃±2℃ and cooling to 90℃, put the dishes and the thermometer placed in a desiccator, cool it down to room temperature and weigh it, to the nearest 0.001g. Repeat the above operations until two continuous results do not exceed 2mg.
5 Expression of Analysis Results
Moisture and volatile matter content (X) are expressed by a mass fraction and calculated using Equation (1):
(1)
Where,
X——the moisture and volatile matter content, %;
m1——the mass of the dish, thermometer and test sample before heating, (g);
m2——the mass of the dish, thermometer and test sample after heating, (g);
m0——the mass of the dish and thermometer, (g);
100——the unit conversion.
The calculation result is accurate to two decimal places.
6 Precision
The absolute difference between two independent determination results under repeatability conditions shall not exceed 10% of their arithmetic mean.
Method II Electrically Heated Drying Oven Method
7 Principle
Same as Chapter 2.
8 Apparatus
8.1 Analytical balance: sensitivity of 0.001g.
8.2 Glass container: flat bottom, in diameter of about 50m, with height of about 30mm.
8.3 Electrically heated drying oven: the main control temperature is 103℃±2℃.
8.4 Dryer: contains an effective desiccant.
9 Analytical Procedures
9.1 Preparation of sample
According to an expected moisture and volatile matter content of sample, weigh 10g or 5g of sample (to the nearest 0.001g) in a pre-dried and weighed glass container.
9.2 Sample determination
Place a glass container containing the sample into a 103℃±2℃ electrically heated drying oven for 1h, and then transfer it in a drier, cool it down to room temperature and weigh it, accurate to 0.001g. Repeat the steps of heating, cooling and weighing. Keep each re-drying 30min until the difference between two successive weighings is not more than 2mg (5g sample) or 4mg (10g sample) respectively depending on the sample mass.
Note: After repeated heating for multiple times, if the grease sample is auto-oxidized and the mass is increased, the minimum value of the previous measurements can be taken.
