GB/T 6434-2006 Determination of crude fat in feed

GB/T 6434-2006 Determination of crude fat in feed

1 Theme content and scope of application

This standard specifies the method for the determination of crude fat in feed. (The practical national standard method for measuring crude fat is time-consuming and inefficient. Therefore, if it is not necessary, we usually use an instrument for direct measurement, such as a crude fat analyzer. It has a variety of models, such as the SZF-06A crude fat analyzer, SZF- 06B crude fat analyzer, SZF-06 crude fat analyzer three, if friends need more information, you can call the 24-hour service hotline at any time

This standard applies to all kinds of single, mixed, compound feeds and premixes.

2 Principle

A Soxhlet fat extractor extracts the sample with ether and weighs the extract. Besides fat, it also contains organic acids, phospholipids, fat-soluble vitamins, chlorophyll, etc. The result is called crude fat or ether extract.

3 Reagents

3.1 Anhydrous ethyl ether (analytically pure).

4 Equipment

4.1 Sample grinders or mortars for laboratories.

4.2 Sample Screen: Aperture: 0.45mm.

4.3 Analytical balance: Sensitivity 0.0001g.

4.4 electric constant temperature water bath: room temperature ~ 100 °C.

4.5 constant temperature oven: 50 ~ 200 °C.

4.6 Soxhlet fat extractor (with spherical condenser): 100 or 150 mL.

4.7 Soxhlet fat extractor.

4.8 filter paper or filter paper tube: medium speed, degreasing.

4.9 Dryer: Use desalinizer with calcium chloride (dry grade) or discolored silica gel.

5 sample selection

A representative sample was selected and the sample was reduced to 500 g by quartering, comminuted to 40 mesh, and further reduced to 200 g in a sealed container using four minutes.

6 analysis steps

6.1 Arbitration method: Determined using a Soxhlet fat extractor.

The Soxhlet extractor (4.6) should be dry and dry. The extraction flask (with several zeolites inside) was dried in a 105±2°C oven (4.5) for 60 min, cooled in a desiccator (4.9) for 30 min, and weighed. After drying for 30 minutes, the same cooling and weighing, the difference between the two weights is less than 0.0008g is a constant weight.

Weigh the sample 1 ~ 5g (accurate to 0.0002g), in the filter paper tube, or wrapped with filter paper, placed in a 105 °C oven (4.5), drying 120min (or into the dry sample after the determination of water, converted into Air-dried sample weight), filter paper tube or bag into the extraction tube, add anhydrous ether (3.1) 60-100 mL in the extraction bottle, heating in a 60-75°C water bath (with distilled water), make ether (3.1) For reflux, control the reflux of ether (3.1) to about 10 times per hour, return 50 times in total (about 70 samples with high oil content) or check the ether (3.1) flowing out of the extraction tube and leave no trace of oil after pumping. To mention the end.

Take out the sample, there is still the original extractor to recover ether until the extraction bottle is completely finished, remove the extraction bottle, and evaporate the residual ether on the water bath. Wipe the outer wall of the bottle. Put the extraction bottle into a 105±2°C oven (4.5) to dry it for 120 min, cool it in a desiccator (4.9) for 30 min, and then dry it for 30 min, and then cool and weigh. The difference between the two weights is less than 0.001g. weight.

6.2 Recommended Method: Determined using a fat extractor (4.7). According to each instrument operating instructions for the determination.

7 Calculation of measurement results

7.1 Calculation See the following formula

Crude fat (%)=(m2-m1)×100/m

Where: m - air-dried sample weight, g.

M1-- The weight of the extracted bottle, g.

M2-- The weight of the extracted bottle with constant weight, g.

7.2 Repeatability

Each sample was taken twice in parallel and the arithmetic average was used as the result.

When the crude fat content is ≥10%, the allowable relative deviation is 3%.

When the crude fat content is 10%, the relative deviation is 5%.