Crop seed crude fat determination method

1 Scope of application

This standard (oil weight method) applies to the determination of crude fat content of oil crop seeds. In the determination of a large number of samples, the residual method can be used (see Appendix A), but the arbitration method is based on the oil weight method.

2 Instruments and equipment

2.1 Analytical balance: Sensitivity 0.0001g;
2.2 Lab grinders for research;
2.3 Electric constant temperature water bath;
2.4 Electrothermal Incubators;
2.5 filter paper tube: diameter 22 × 100 mm;
2.6 Desiccator with discoloration silica gel;
2.7 Soxhlet's fat extractor: 60 ml or 150 ml;
2.8 Copper wire screen: aperture 0.42 mm (40 mesh).

3 Reagents

Anhydrous ether: chemically pure.

4 sample selection and preparation

4.1 Select representative seeds, sort out impurities, and reduce sampling by quartering. The sample was selected and prepared, mixed immediately, and placed in a ground-mouth bottle for use.
4.2 Small seeds, such as sesame and rapeseed, should not be less than 25 grams.
4.3 Large seeds, such as soybeans, peanuts, etc., should not be less than 30 grams. Soybeans were dried at 105±2°C for 1 hour, crushed and passed through a 40 mesh sieve; peanuts were chopped.
4.4 Shelled oil seeds, such as peanuts, castor beans, sunflower seeds, etc., should not be less than 50 grams. Peel the shells one by one and weigh them separately to calculate the kernel rate. Then chop the children.

5 Measurement procedure

5.1 Weigh 2 to 4 grams of spare sample (oil 0.7-1 gram), accurate to 0.001 grams. Placed in a 105°C 2°C oven, dried for 1 hour, removed, placed in a desiccator and allowed to cool to room temperature. At the same time another test sample moisture.
5.2 Put the sample into the mortar and mortar, and if necessary, add appropriate amount of pure quartz sand to help the research. Use the angle spoon to move the thinned sample into the dry filter paper tube, and take a small amount of cotton wool to remove the residue. Samples and oil traces from mortars, hammers, and angle spoons are also put into the filter paper tube (soybeans have been pre-baked and crushed by GB 2906-82, and can be directly called sample loading cylinders), and the surface of the samples is covered with absorbent cotton. , Then put the filter paper tube into the extraction tube.
5.3 In a clean extraction bottle containing 2-3 pumice stones and baked to a constant weight, add about 1/2 of anhydrous ether in the bottle body, and connect the parts of the extractor to open the condensate flow. , extract on a water bath. The water bath temperature was adjusted so that the rate of condensation of the dropped ether was 180 drops/minute. The extraction time generally takes 8 to 10 hours. For crop seeds with high oil content, the extraction time should be extended until the ethyl ether in the extraction tube is extracted at the end of the test with no oil traces.
5.4 After extraction, remove the filter paper tube from the extraction tube, connect the extractor, and distill the ether in the extraction flask on the water bath. Remove the extraction flask and evaporate the residual ether on a boiling water bath.
5. 5 Place the extraction bottle containing the crude fat in an oven at 105±2°C for 1 hour. Cool in a desiccator to room temperature (about 45 to 60 minutes) and weigh it. Accurate to O. 0001 grams, bake for another 30 minutes, cool and weigh until constant weight. The weight added to the extraction bottle is the weight of crude fat, and the extracted oil should be clear. Otherwise it should be redone.

6 Calculation of measurement results

6.1 Calculation formula Crude fat, % (dry basis) =, Crude fat weight / Sample weight (1 - Moisture percentage) × 100
Shelled oil seed crude fat % = kernel crude fat % × kernel rate %
6.2 The result of the parallel determination is expressed as an arithmetic average, retaining two decimal places.
6.3 The relative difference in the results of parallel determinations, soybeans should not be greater than 2%, and oilseeds seeds should not be greater than 1%.